name	htmx-rust
description	Build interactive hypermedia-driven applications with Axum and HTMX. Use when creating dynamic UIs, real-time updates, AJAX interactions, mentions 'HTMX', 'dynamic content', or 'interactive web app'.

HTMX + Axum Integration (Rust)

Overview

HTMX enables modern, interactive web applications with minimal JavaScript. Combined with Rust's type safety and Axum's powerful routing, you get fast, reliable hypermedia-driven UIs with compile-time guarantees.

Key Benefits:

No JavaScript framework needed
Server-side rendering with Askama templates
Type-safe request/response handling with Axum extractors
Minimal client-side code
Progressive enhancement
Memory safety and zero-cost abstractions

When to Use This Skill

Use when:

Building interactive UIs with server-side rendering
Creating dynamic content updates
User mentions "HTMX", "dynamic updates", "real-time"
Implementing AJAX-like behavior without JS
Building interactive web apps without SPAs

Quick Start

1. Add Dependencies

[dependencies]
axum = "0.7"
tokio = { version = "1", features = ["full"] }
askama = "0.12"
serde = { version = "1.0", features = ["derive"] }

2. Create Base Template (Askama)

<!DOCTYPE html>
<html>
    <head>
        <title>{{ title }}</title>
        <script src="https://unpkg.com/htmx.org@1.9.10"></script>
    </head>
    <body>
        {{ content }}
    </body>
</html>

3. Create Interactive Component

{# counter.html #}
<div id="counter">
    <p>Count: {{ count }}</p>
    <button
        hx-post="/counter/increment"
        hx-target="#counter"
        hx-swap="outerHTML"
    >
        Increment
    </button>
</div>

Define the template struct:

use askama::Template;

#[derive(Template)]
#[template(path = "counter.html")]
struct CounterTemplate {
    count: i32,
}

4. Create Handler

use axum::{
    extract::{State},
    response::IntoResponse,
    Json,
};

async fn increment_counter(
    State(state): State<AppState>,
) -> impl IntoResponse {
    let mut count = state.counter.lock().unwrap();
    *count += 1;

    CounterTemplate { count: *count }
}

5. Setup Router

use axum::{routing::post, Router};

#[tokio::main]
async fn main() {
    let app = Router::new()
        .route("/counter/increment", post(increment_counter))
        .with_state(AppState::default());

    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
        .await
        .unwrap();

    axum::serve(listener, app).await.unwrap();
}

Core HTMX Attributes

hx-get / hx-post

Trigger HTTP requests with Axum extractors:

{# search.html #}
<input
    type="text"
    name="q"
    hx-get="/search"
    hx-trigger="keyup changed delay:500ms"
    hx-target="#results"
/>
<div id="results"></div>

Handler with type-safe query parameters:

use axum::extract::Query;
use serde::Deserialize;

#[derive(Deserialize)]
struct SearchQuery {
    q: String,
}

#[derive(Template)]
#[template(path = "search_results.html")]
struct SearchResults {
    results: Vec<String>,
}

async fn search(Query(params): Query<SearchQuery>) -> impl IntoResponse {
    let results = perform_search(&params.q);
    SearchResults { results }
}

hx-target

Specify where to insert response:

{# load_more.html #}
<button
    hx-get="/posts?page=2"
    hx-target="#posts"
    hx-swap="beforeend"
>
    Load More
</button>

hx-swap

Control how content is swapped:

{# swap options #}
<!-- innerHTML (default) -->
hx-swap="innerHTML"

<!-- outerHTML - replace element itself -->
hx-swap="outerHTML"

<!-- beforeend - append inside -->
hx-swap="beforeend"

<!-- afterend - insert after -->
hx-swap="afterend"

hx-trigger

Control when requests fire:

<!-- On click (default for buttons) -->
<button hx-get="/data">Click me</button>

<!-- On change -->
<select hx-get="/filter" hx-trigger="change">

<!-- On keyup with delay -->
<input hx-get="/search" hx-trigger="keyup changed delay:300ms">

<!-- On page load -->
<div hx-get="/data" hx-trigger="load">

<!-- Every 5 seconds -->
<div hx-get="/updates" hx-trigger="every 5s">

Common Patterns

Pattern 1: Live Search

Component template (search_box.html):

<div>
    <input
        type="text"
        name="q"
        placeholder="Search..."
        hx-get="/search"
        hx-trigger="keyup changed delay:500ms"
        hx-target="#search-results"
        hx-indicator="#spinner"
    />
    <span id="spinner" class="htmx-indicator">
        Searching...
    </span>
</div>
<div id="search-results"></div>

Results template (search_results.html):

<ul>
    {% for result in results %}
        <li>{{ result }}</li>
    {% endfor %}
</ul>

Handler:

use axum::extract::Query;
use askama::Template;
use serde::Deserialize;

#[derive(Deserialize)]
struct SearchParams {
    q: String,
}

#[derive(Template)]
#[template(path = "search_results.html")]
struct SearchResults {
    results: Vec<String>,
}

async fn search(Query(params): Query<SearchParams>) -> impl IntoResponse {
    let results = perform_search(&params.q);
    SearchResults { results }
}

Pattern 2: Infinite Scroll

Template (post_list.html):

<div id="posts">
    {% for post in posts %}
        <div class="post-card">{{ post.title }}</div>
    {% endfor %}
</div>

{% if !posts.is_empty() %}
    <div
        hx-get="/posts?page={{ page + 1 }}"
        hx-trigger="revealed"
        hx-swap="outerHTML"
    >
        Loading more...
    </div>
{% endif %}

Handler:

use axum::extract::Query;
use serde::Deserialize;

#[derive(Deserialize)]
struct PageParams {
    page: u32,
}

#[derive(Template)]
#[template(path = "post_list.html")]
struct PostList {
    posts: Vec<Post>,
    page: u32,
}

async fn list_posts(Query(params): Query<PageParams>) -> impl IntoResponse {
    let posts = fetch_posts(params.page);
    PostList {
        posts,
        page: params.page,
    }
}

Pattern 3: Delete with Confirmation

Template (delete_button.html):

<button
    hx-delete="/items/{{ item_id }}"
    hx-confirm="Are you sure?"
    hx-target="closest tr"
    hx-swap="outerHTML swap:1s"
>
    Delete
</button>

Handler:

use axum::extract::Path;
use axum::http::StatusCode;

async fn delete_item(Path(item_id): Path<String>) -> StatusCode {
    delete_from_database(&item_id);
    StatusCode::OK  // Empty response removes element
}

Pattern 4: Inline Edit

Display template (editable_field.html):

<div id="field-{{ id }}">
    <span>{{ value }}</span>
    <button
        hx-get="/edit/{{ id }}"
        hx-target="#field-{{ id }}"
        hx-swap="outerHTML"
    >
        Edit
    </button>
</div>

Edit form template (edit_form.html):

<form
    hx-post="/save/{{ id }}"
    hx-target="#field-{{ id }}"
    hx-swap="outerHTML"
>
    <input type="text" name="value" value="{{ value }}" />
    <button type="submit">Save</button>
    <button
        hx-get="/cancel/{{ id }}"
        hx-target="#field-{{ id }}"
    >
        Cancel
    </button>
</form>

Handlers:

use axum::extract::Path;
use axum::Form;
use serde::Deserialize;

#[derive(Deserialize)]
struct SaveData {
    value: String,
}

#[derive(Template)]
#[template(path = "editable_field.html")]
struct EditableField {
    id: String,
    value: String,
}

#[derive(Template)]
#[template(path = "edit_form.html")]
struct EditForm {
    id: String,
    value: String,
}

async fn show_edit_form(Path(id): Path<String>) -> impl IntoResponse {
    let value = fetch_field(&id);
    EditForm { id, value }
}

async fn save_field(
    Path(id): Path<String>,
    Form(data): Form<SaveData>,
) -> impl IntoResponse {
    update_field(&id, &data.value);
    EditableField {
        id,
        value: data.value,
    }
}

async fn cancel_edit(Path(id): Path<String>) -> impl IntoResponse {
    let value = fetch_field(&id);
    EditableField { id, value }
}

Pattern 5: Form Validation

Template (signup_form.html):

<form hx-post="/signup" hx-target="#form-errors">
    <div id="form-errors"></div>

    <input
        type="email"
        name="email"
        hx-post="/validate/email"
        hx-trigger="blur"
        hx-target="#email-error"
    />
    <div id="email-error"></div>

    <input type="password" name="password" />

    <button type="submit">Sign Up</button>
</form>

Validation template (validation_error.html):

<span class="error">{{ message }}</span>

Handlers:

use axum::Form;
use serde::Deserialize;

#[derive(Deserialize)]
struct EmailValidation {
    email: String,
}

#[derive(Template)]
#[template(path = "validation_error.html")]
struct ValidationError {
    message: String,
}

async fn validate_email(Form(data): Form<EmailValidation>) -> impl IntoResponse {
    if is_email_valid(&data.email) {
        (StatusCode::OK, "").into_response()
    } else {
        ValidationError {
            message: "Invalid email format".to_string(),
        }
        .into_response()
    }
}

Pattern 6: Polling / Real-time Updates

Template (live_stats.html):

<div
    hx-get="/stats"
    hx-trigger="load, every 5s"
    hx-swap="innerHTML"
>
    Loading stats...
</div>

Stats template (stats_display.html):

<div>
    <p>Users online: {{ stats.users_online }}</p>
    <p>Active sessions: {{ stats.sessions }}</p>
</div>

Handler:

use askama::Template;

#[derive(Template)]
#[template(path = "stats_display.html")]
struct StatsDisplay {
    stats: Stats,
}

#[derive(Clone)]
struct Stats {
    users_online: usize,
    sessions: usize,
}

async fn get_stats() -> impl IntoResponse {
    let stats = fetch_current_stats();
    StatsDisplay { stats }
}

Advanced Patterns

Out-of-Band Updates (OOB)

Update multiple parts of page in a single request:

Cart button template (cart_button.html):

<button id="cart-btn">
    Cart ({{ count }})
</button>

Add to cart response template (add_to_cart_response.html):

<!-- Main response -->
<div class="notification">
    Added {{ item.name }} to cart!
</div>

<!-- Update cart button (different part of page) -->
<div id="cart-btn" hx-swap-oob="true">
    <button id="cart-btn">
        Cart ({{ new_count }})
    </button>
</div>

Handler:

use axum::Form;
use serde::Deserialize;

#[derive(Deserialize)]
struct AddToCart {
    item_id: String,
}

#[derive(Template)]
#[template(path = "add_to_cart_response.html")]
struct AddToCartResponse {
    item: Item,
    new_count: usize,
}

async fn add_to_cart(Form(data): Form<AddToCart>) -> impl IntoResponse {
    let item = fetch_item(&data.item_id);
    let new_count = add_to_cart_db(&data.item_id);

    AddToCartResponse { item, new_count }
}

Progressive Enhancement

Template that works with and without HTMX:

<form
    action="/submit"
    method="POST"
    hx-post="/submit"
    hx-target="#result"
>
    <input type="text" name="data" />
    <button type="submit">Submit</button>
</form>
<div id="result"></div>

Works without JavaScript (form submission), enhanced with HTMX (no page reload).

Loading States

Template:

<div
    hx-get="/data"
    hx-trigger="load"
    hx-indicator="#loading"
>
    <div id="loading" class="htmx-indicator">
        Loading data...
    </div>
</div>

CSS:

.htmx-indicator {
    display: none;
}

.htmx-request .htmx-indicator {
    display: inline;
}

.htmx-request.htmx-indicator {
    display: inline;
}

Response Headers

HX-Trigger

Trigger client-side custom events:

use axum::http::HeaderMap;

async fn create_item(Form(data): Form<ItemForm>) -> impl IntoResponse {
    let item = create_in_db(data);

    let mut headers = HeaderMap::new();
    headers.insert("HX-Trigger", "itemCreated".parse().unwrap());

    (headers, ItemTemplate { item })
}

Client side:

document.body.addEventListener("itemCreated", function(evt) {
    console.log("Item created!");
});

HX-Redirect

Redirect to new page after form submission:

async fn login(Form(credentials): Form<LoginForm>) -> impl IntoResponse {
    if authenticate(&credentials) {
        let mut headers = HeaderMap::new();
        headers.insert("HX-Redirect", "/dashboard".parse().unwrap());
        (headers, StatusCode::OK)
    } else {
        (StatusCode::UNAUTHORIZED, "Invalid credentials")
    }
}

HX-Refresh

Trigger a full page refresh:

async fn update_config(Form(config): Form<Config>) -> impl IntoResponse {
    save_config(config);

    let mut headers = HeaderMap::new();
    headers.insert("HX-Refresh", "true".parse().unwrap());

    (headers, StatusCode::OK)
}

Best Practices

Keep handlers focused - Return only the HTML fragment needed
Use semantic HTML - Works without JS, enhanced with HTMX
Type-safe extractors - Leverage Axum's built-in form/query validation
Handle errors gracefully - Return error components with appropriate status codes
Optimize responses - Send minimal HTML, only what changed
Use OOB for multi-updates - Update multiple page sections efficiently
Progressive enhancement - Always provide fallback (form action attribute)
Leverage Rust's type system - Encode validation rules in types, not handlers

Testing HTMX Handlers

Use the fluent Given-When-Then DSL pattern for acceptance testing HTMX interactions:

Pattern 1: Simple Live Search

Template Setup:

{# search.html #}
<input
    type="text"
    name="q"
    hx-get="/search"
    hx-trigger="keyup changed delay:500ms"
    hx-target="#search-results"
/>
<div id="search-results"></div>

Handler:

#[derive(Deserialize)]
struct SearchParams {
    q: String,
}

#[derive(Template)]
#[template(path = "search_results.html")]
struct SearchResults {
    results: Vec<String>,
}

async fn search(Query(params): Query<SearchParams>) -> impl IntoResponse {
    let results = perform_search(&params.q);
    SearchResults { results }
}

Acceptance Test:

#[tokio::test]
async fn live_search_should_return_matching_results() {
    WebApp::given()
        .a_file_with_content(
            "## TT 2025-01-15\n\
             - #frontend 2h Building search UI\n\
             - #backend 1h Search API\n\
             - #docs 30m Search documentation\n",
        )
        .when_get("/search")
        .with_query("q=search")
        .should_succeed()
        .await
        .expect_status(200)
        .expect_contains("Search API")
        .expect_contains("Search documentation");
}

#[tokio::test]
async fn live_search_should_handle_empty_query() {
    WebApp::given()
        .when_get("/search")
        .with_query("q=")
        .should_succeed()
        .await
        .expect_status(200)
        .expect_not_contains("Search API");
}

★ Insight ───────────────────────────────────── The test names describe the HTMX behavior users experience: "should return matching results" communicates the interaction pattern. By testing through the /search endpoint with query parameters, you're verifying the handler correctly processes HTMX requests without testing JavaScript—pure server-side hypermedia. ─────────────────────────────────────────────────

Pattern 2: Form Submission with Validation

Template:

<form hx-post="/items" hx-target="#items">
    <input type="text" name="title" required />
    <button type="submit">Add Item</button>
</form>
<div id="items"></div>

Handler:

#[derive(Deserialize)]
struct CreateItem {
    title: String,
}

#[derive(Template)]
#[template(path = "item.html")]
struct ItemTemplate {
    item: Item,
}

async fn create_item(Form(data): Form<CreateItem>) -> impl IntoResponse {
    if data.title.is_empty() {
        return (StatusCode::BAD_REQUEST, "Title required").into_response();
    }

    let item = Item::create(data.title);
    ItemTemplate { item }.into_response()
}

Acceptance Tests:

#[tokio::test]
async fn form_submission_should_create_item() {
    WebApp::given()
        .when_post("/items")
        .with_form_data(&[("title", "New Task")])
        .should_succeed()
        .await
        .expect_status(200)
        .expect_contains("New Task");
}

#[tokio::test]
async fn form_submission_should_reject_empty_title() {
    WebApp::given()
        .when_post("/items")
        .with_form_data(&[("title", "")])
        .should_fail()
        .await
        .expect_status(400)
        .expect_contains("Title required");
}

Pattern 3: Delete with Confirmation

Handler:

async fn delete_item(Path(item_id): Path<String>) -> StatusCode {
    delete_from_database(&item_id);
    StatusCode::OK
}

Acceptance Test:

#[tokio::test]
async fn delete_button_should_remove_item() {
    WebApp::given()
        .a_file_with_content(
            "## TT 2025-01-15\n\
             - #project-alpha 2h Work\n",
        )
        .when_delete("/items/project-alpha")
        .should_succeed()
        .await
        .expect_status(200);
}

Pattern 4: Out-of-Band Updates

Handler returning OOB response:

#[derive(Template)]
#[template(path = "add_to_cart_response.html")]
struct AddToCartResponse {
    notification: String,
    cart_count: usize,
}

async fn add_to_cart(Form(data): Form<AddToCart>) -> impl IntoResponse {
    add_to_cart_db(&data.item_id);
    let count = get_cart_count();

    AddToCartResponse {
        notification: format!("Added {} to cart", data.item_id),
        cart_count: count,
    }
}

Template with OOB:

{# add_to_cart_response.html #}
<!-- Main response -->
<div class="notification">{{ notification }}</div>

<!-- Out-of-band update: cart button elsewhere on page -->
<button id="cart-btn" hx-swap-oob="true">
    Cart ({{ cart_count }})
</button>

Acceptance Test:

#[tokio::test]
async fn add_to_cart_should_update_cart_button() {
    WebApp::given()
        .when_post("/add-to-cart")
        .with_form_data(&[("item_id", "widget-123")])
        .should_succeed()
        .await
        .expect_status(200)
        .expect_contains("Added widget-123 to cart")
        .expect_contains("Cart (1)");  // OOB update verified
}

★ Insight ───────────────────────────────────── Testing OOB updates verifies that a single response fragment updates multiple page sections—a powerful HTMX pattern. The test reads naturally: "should update cart button" communicates the user-visible effect without mentioning implementation details. This acceptance-test style ensures the actual rendered HTML behaves correctly. ─────────────────────────────────────────────────

Pattern 5: Real-time Polling

Handler:

async fn get_stats() -> impl IntoResponse {
    let stats = fetch_current_stats();
    StatsDisplay { stats }
}

Acceptance Test:

#[tokio::test]
async fn stats_endpoint_should_return_current_data() {
    WebApp::given()
        .when_get("/stats")
        .should_succeed()
        .await
        .expect_status(200)
        .expect_contains("Users online")
        .expect_contains("Active sessions");
}

Testing Best Practices

Test the handler, not the JavaScript - HTMX is client-side; your Rust handler only needs to return correct HTML
Use descriptive test names - Name tests after the user-visible behavior ("should update cart button")
Verify HTML response content - Assert the returned template renders with correct data
Test error paths - Verify handlers return appropriate status codes for invalid requests
Test OOB updates - When using out-of-band updates, verify all parts appear in response
Keep tests focused - Each test should verify one interaction pattern

Full Example: Todo App

Templates:

todo_app.html:

<!DOCTYPE html>
<html>
<head>
    <title>Todo App</title>
    <script src="https://unpkg.com/htmx.org@1.9.10"></script>
</head>
<body>
    <div>
        <h1>My Todos</h1>
        <form
            hx-post="/todos"
            hx-target="#todo-list"
            hx-swap="beforeend"
            hx-on::after-request="this.reset()"
        >
            <input
                type="text"
                name="text"
                placeholder="New todo..."
                required
            />
            <button type="submit">Add</button>
        </form>

        <ul id="todo-list">
            {% for todo in todos %}
                <li id="todo-{{ todo.id }}">
                    <input
                        type="checkbox"
                        {% if todo.completed %}checked{% endif %}
                        hx-post="/todos/{{ todo.id }}/toggle"
                        hx-target="#todo-{{ todo.id }}"
                        hx-swap="outerHTML"
                    />
                    <span class="{% if todo.completed %}completed{% endif %}">
                        {{ todo.text }}
                    </span>
                    <button
                        hx-delete="/todos/{{ todo.id }}"
                        hx-target="#todo-{{ todo.id }}"
                        hx-swap="outerHTML swap:500ms"
                    >
                        Delete
                    </button>
                </li>
            {% endfor %}
        </ul>
    </div>
</body>
</html>

Rust implementation:

use axum::{
    extract::{Path, State},
    Form, Router,
    routing::{get, post, delete},
    http::StatusCode,
    response::IntoResponse,
};
use askama::Template;
use serde::Deserialize;
use std::sync::Mutex;

#[derive(Clone)]
struct Todo {
    id: String,
    text: String,
    completed: bool,
}

#[derive(Clone)]
struct AppState {
    todos: std::sync::Arc<Mutex<Vec<Todo>>>,
}

#[derive(Template)]
#[template(path = "todo_app.html")]
struct TodoApp {
    todos: Vec<Todo>,
}

#[derive(Template)]
#[template(path = "todo_item.html")]
struct TodoItem {
    todo: Todo,
}

#[derive(Deserialize)]
struct CreateTodo {
    text: String,
}

async fn list_todos(State(state): State<AppState>) -> impl IntoResponse {
    let todos = state.todos.lock().unwrap().clone();
    TodoApp { todos }
}

async fn create_todo(
    State(state): State<AppState>,
    Form(form): Form<CreateTodo>,
) -> impl IntoResponse {
    let todo = Todo {
        id: uuid::Uuid::new_v4().to_string(),
        text: form.text,
        completed: false,
    };

    state.todos.lock().unwrap().push(todo.clone());
    TodoItem { todo }
}

async fn toggle_todo(
    State(state): State<AppState>,
    Path(id): Path<String>,
) -> impl IntoResponse {
    let mut todos = state.todos.lock().unwrap();
    if let Some(todo) = todos.iter_mut().find(|t| t.id == id) {
        todo.completed = !todo.completed;
        TodoItem { todo: todo.clone() }
    } else {
        StatusCode::NOT_FOUND.into_response()
    }
}

async fn delete_todo(
    State(state): State<AppState>,
    Path(id): Path<String>,
) -> StatusCode {
    let mut todos = state.todos.lock().unwrap();
    todos.retain(|t| t.id != id);
    StatusCode::OK
}

#[tokio::main]
async fn main() {
    let state = AppState {
        todos: std::sync::Arc::new(Mutex::new(vec![])),
    };

    let app = Router::new()
        .route("/todos", get(list_todos).post(create_todo))
        .route("/todos/:id/toggle", post(toggle_todo))
        .route("/todos/:id", delete(delete_todo))
        .with_state(state);

    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
        .await
        .unwrap();

    axum::serve(listener, app).await.unwrap();
}

Resources

Next Steps

Style components → Use CSS frameworks (Tailwind, Bootstrap)
Add state management → Consider database integration
Deploy → Use Docker, Railway, or cloud platforms
Test → Use the WebApp DSL for comprehensive acceptance tests

name	htmx-rust
description	Build interactive hypermedia-driven applications with Axum and HTMX. Use when creating dynamic UIs, real-time updates, AJAX interactions, mentions 'HTMX', 'dynamic content', or 'interactive web app'.

HTMX + Axum Integration (Rust)

Overview

Key Benefits:

No JavaScript framework needed
Server-side rendering with Askama templates
Type-safe request/response handling with Axum extractors
Minimal client-side code
Progressive enhancement
Memory safety and zero-cost abstractions

When to Use This Skill

Use when:

Building interactive UIs with server-side rendering
Creating dynamic content updates
User mentions "HTMX", "dynamic updates", "real-time"
Implementing AJAX-like behavior without JS
Building interactive web apps without SPAs

Quick Start

1. Add Dependencies

[dependencies]
axum = "0.7"
tokio = { version = "1", features = ["full"] }
askama = "0.12"
serde = { version = "1.0", features = ["derive"] }

2. Create Base Template (Askama)

<!DOCTYPE html>
<html>
    <head>
        <title>{{ title }}</title>
        <script src="https://unpkg.com/htmx.org@1.9.10"></script>
    </head>
    <body>
        {{ content }}
    </body>
</html>

3. Create Interactive Component

{# counter.html #}
<div id="counter">
    <p>Count: {{ count }}</p>
    <button
        hx-post="/counter/increment"
        hx-target="#counter"
        hx-swap="outerHTML"
    >
        Increment
    </button>
</div>

Define the template struct:

use askama::Template;

#[derive(Template)]
#[template(path = "counter.html")]
struct CounterTemplate {
    count: i32,
}

4. Create Handler

use axum::{
    extract::{State},
    response::IntoResponse,
    Json,
};

async fn increment_counter(
    State(state): State<AppState>,
) -> impl IntoResponse {
    let mut count = state.counter.lock().unwrap();
    *count += 1;

    CounterTemplate { count: *count }
}

5. Setup Router

use axum::{routing::post, Router};

#[tokio::main]
async fn main() {
    let app = Router::new()
        .route("/counter/increment", post(increment_counter))
        .with_state(AppState::default());

    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
        .await
        .unwrap();

    axum::serve(listener, app).await.unwrap();
}

Core HTMX Attributes

hx-get / hx-post

Trigger HTTP requests with Axum extractors:

{# search.html #}
<input
    type="text"
    name="q"
    hx-get="/search"
    hx-trigger="keyup changed delay:500ms"
    hx-target="#results"
/>
<div id="results"></div>

Handler with type-safe query parameters:

use axum::extract::Query;
use serde::Deserialize;

#[derive(Deserialize)]
struct SearchQuery {
    q: String,
}

#[derive(Template)]
#[template(path = "search_results.html")]
struct SearchResults {
    results: Vec<String>,
}

async fn search(Query(params): Query<SearchQuery>) -> impl IntoResponse {
    let results = perform_search(&params.q);
    SearchResults { results }
}

hx-target

Specify where to insert response:

{# load_more.html #}
<button
    hx-get="/posts?page=2"
    hx-target="#posts"
    hx-swap="beforeend"
>
    Load More
</button>

hx-swap

Control how content is swapped:

{# swap options #}
<!-- innerHTML (default) -->
hx-swap="innerHTML"

<!-- outerHTML - replace element itself -->
hx-swap="outerHTML"

<!-- beforeend - append inside -->
hx-swap="beforeend"

<!-- afterend - insert after -->
hx-swap="afterend"

hx-trigger

Control when requests fire:

<!-- On click (default for buttons) -->
<button hx-get="/data">Click me</button>

<!-- On change -->
<select hx-get="/filter" hx-trigger="change">

<!-- On keyup with delay -->
<input hx-get="/search" hx-trigger="keyup changed delay:300ms">

<!-- On page load -->
<div hx-get="/data" hx-trigger="load">

<!-- Every 5 seconds -->
<div hx-get="/updates" hx-trigger="every 5s">

Common Patterns

Pattern 1: Live Search

Component template (search_box.html):

<div>
    <input
        type="text"
        name="q"
        placeholder="Search..."
        hx-get="/search"
        hx-trigger="keyup changed delay:500ms"
        hx-target="#search-results"
        hx-indicator="#spinner"
    />
    <span id="spinner" class="htmx-indicator">
        Searching...
    </span>
</div>
<div id="search-results"></div>

Results template (search_results.html):

<ul>
    {% for result in results %}
        <li>{{ result }}</li>
    {% endfor %}
</ul>

Handler:

use axum::extract::Query;
use askama::Template;
use serde::Deserialize;

#[derive(Deserialize)]
struct SearchParams {
    q: String,
}

#[derive(Template)]
#[template(path = "search_results.html")]
struct SearchResults {
    results: Vec<String>,
}

async fn search(Query(params): Query<SearchParams>) -> impl IntoResponse {
    let results = perform_search(&params.q);
    SearchResults { results }
}

Pattern 2: Infinite Scroll

Template (post_list.html):

<div id="posts">
    {% for post in posts %}
        <div class="post-card">{{ post.title }}</div>
    {% endfor %}
</div>

{% if !posts.is_empty() %}
    <div
        hx-get="/posts?page={{ page + 1 }}"
        hx-trigger="revealed"
        hx-swap="outerHTML"
    >
        Loading more...
    </div>
{% endif %}

Handler:

use axum::extract::Query;
use serde::Deserialize;

#[derive(Deserialize)]
struct PageParams {
    page: u32,
}

#[derive(Template)]
#[template(path = "post_list.html")]
struct PostList {
    posts: Vec<Post>,
    page: u32,
}

async fn list_posts(Query(params): Query<PageParams>) -> impl IntoResponse {
    let posts = fetch_posts(params.page);
    PostList {
        posts,
        page: params.page,
    }
}

Pattern 3: Delete with Confirmation

Template (delete_button.html):

<button
    hx-delete="/items/{{ item_id }}"
    hx-confirm="Are you sure?"
    hx-target="closest tr"
    hx-swap="outerHTML swap:1s"
>
    Delete
</button>

Handler:

use axum::extract::Path;
use axum::http::StatusCode;

async fn delete_item(Path(item_id): Path<String>) -> StatusCode {
    delete_from_database(&item_id);
    StatusCode::OK  // Empty response removes element
}

Pattern 4: Inline Edit

Display template (editable_field.html):

<div id="field-{{ id }}">
    <span>{{ value }}</span>
    <button
        hx-get="/edit/{{ id }}"
        hx-target="#field-{{ id }}"
        hx-swap="outerHTML"
    >
        Edit
    </button>
</div>

Edit form template (edit_form.html):

<form
    hx-post="/save/{{ id }}"
    hx-target="#field-{{ id }}"
    hx-swap="outerHTML"
>
    <input type="text" name="value" value="{{ value }}" />
    <button type="submit">Save</button>
    <button
        hx-get="/cancel/{{ id }}"
        hx-target="#field-{{ id }}"
    >
        Cancel
    </button>
</form>

Handlers:

use axum::extract::Path;
use axum::Form;
use serde::Deserialize;

#[derive(Deserialize)]
struct SaveData {
    value: String,
}

#[derive(Template)]
#[template(path = "editable_field.html")]
struct EditableField {
    id: String,
    value: String,
}

#[derive(Template)]
#[template(path = "edit_form.html")]
struct EditForm {
    id: String,
    value: String,
}

async fn show_edit_form(Path(id): Path<String>) -> impl IntoResponse {
    let value = fetch_field(&id);
    EditForm { id, value }
}

async fn save_field(
    Path(id): Path<String>,
    Form(data): Form<SaveData>,
) -> impl IntoResponse {
    update_field(&id, &data.value);
    EditableField {
        id,
        value: data.value,
    }
}

async fn cancel_edit(Path(id): Path<String>) -> impl IntoResponse {
    let value = fetch_field(&id);
    EditableField { id, value }
}

Pattern 5: Form Validation

Template (signup_form.html):

<form hx-post="/signup" hx-target="#form-errors">
    <div id="form-errors"></div>

    <input
        type="email"
        name="email"
        hx-post="/validate/email"
        hx-trigger="blur"
        hx-target="#email-error"
    />
    <div id="email-error"></div>

    <input type="password" name="password" />

    <button type="submit">Sign Up</button>
</form>

Validation template (validation_error.html):

<span class="error">{{ message }}</span>

Handlers:

use axum::Form;
use serde::Deserialize;

#[derive(Deserialize)]
struct EmailValidation {
    email: String,
}

#[derive(Template)]
#[template(path = "validation_error.html")]
struct ValidationError {
    message: String,
}

async fn validate_email(Form(data): Form<EmailValidation>) -> impl IntoResponse {
    if is_email_valid(&data.email) {
        (StatusCode::OK, "").into_response()
    } else {
        ValidationError {
            message: "Invalid email format".to_string(),
        }
        .into_response()
    }
}

Pattern 6: Polling / Real-time Updates

Template (live_stats.html):

<div
    hx-get="/stats"
    hx-trigger="load, every 5s"
    hx-swap="innerHTML"
>
    Loading stats...
</div>

Stats template (stats_display.html):

<div>
    <p>Users online: {{ stats.users_online }}</p>
    <p>Active sessions: {{ stats.sessions }}</p>
</div>

Handler:

use askama::Template;

#[derive(Template)]
#[template(path = "stats_display.html")]
struct StatsDisplay {
    stats: Stats,
}

#[derive(Clone)]
struct Stats {
    users_online: usize,
    sessions: usize,
}

async fn get_stats() -> impl IntoResponse {
    let stats = fetch_current_stats();
    StatsDisplay { stats }
}

Advanced Patterns

Out-of-Band Updates (OOB)

Update multiple parts of page in a single request:

Cart button template (cart_button.html):

<button id="cart-btn">
    Cart ({{ count }})
</button>

Add to cart response template (add_to_cart_response.html):

<!-- Main response -->
<div class="notification">
    Added {{ item.name }} to cart!
</div>

<!-- Update cart button (different part of page) -->
<div id="cart-btn" hx-swap-oob="true">
    <button id="cart-btn">
        Cart ({{ new_count }})
    </button>
</div>

Handler:

use axum::Form;
use serde::Deserialize;

#[derive(Deserialize)]
struct AddToCart {
    item_id: String,
}

#[derive(Template)]
#[template(path = "add_to_cart_response.html")]
struct AddToCartResponse {
    item: Item,
    new_count: usize,
}

async fn add_to_cart(Form(data): Form<AddToCart>) -> impl IntoResponse {
    let item = fetch_item(&data.item_id);
    let new_count = add_to_cart_db(&data.item_id);

    AddToCartResponse { item, new_count }
}

Progressive Enhancement

Template that works with and without HTMX:

<form
    action="/submit"
    method="POST"
    hx-post="/submit"
    hx-target="#result"
>
    <input type="text" name="data" />
    <button type="submit">Submit</button>
</form>
<div id="result"></div>

Works without JavaScript (form submission), enhanced with HTMX (no page reload).

Loading States

Template:

<div
    hx-get="/data"
    hx-trigger="load"
    hx-indicator="#loading"
>
    <div id="loading" class="htmx-indicator">
        Loading data...
    </div>
</div>

CSS:

.htmx-indicator {
    display: none;
}

.htmx-request .htmx-indicator {
    display: inline;
}

.htmx-request.htmx-indicator {
    display: inline;
}

Response Headers

HX-Trigger

Trigger client-side custom events:

use axum::http::HeaderMap;

async fn create_item(Form(data): Form<ItemForm>) -> impl IntoResponse {
    let item = create_in_db(data);

    let mut headers = HeaderMap::new();
    headers.insert("HX-Trigger", "itemCreated".parse().unwrap());

    (headers, ItemTemplate { item })
}

Client side:

document.body.addEventListener("itemCreated", function(evt) {
    console.log("Item created!");
});

HX-Redirect

Redirect to new page after form submission:

async fn login(Form(credentials): Form<LoginForm>) -> impl IntoResponse {
    if authenticate(&credentials) {
        let mut headers = HeaderMap::new();
        headers.insert("HX-Redirect", "/dashboard".parse().unwrap());
        (headers, StatusCode::OK)
    } else {
        (StatusCode::UNAUTHORIZED, "Invalid credentials")
    }
}

HX-Refresh

Trigger a full page refresh:

async fn update_config(Form(config): Form<Config>) -> impl IntoResponse {
    save_config(config);

    let mut headers = HeaderMap::new();
    headers.insert("HX-Refresh", "true".parse().unwrap());

    (headers, StatusCode::OK)
}

Best Practices

Keep handlers focused - Return only the HTML fragment needed
Use semantic HTML - Works without JS, enhanced with HTMX
Type-safe extractors - Leverage Axum's built-in form/query validation
Handle errors gracefully - Return error components with appropriate status codes
Optimize responses - Send minimal HTML, only what changed
Use OOB for multi-updates - Update multiple page sections efficiently
Progressive enhancement - Always provide fallback (form action attribute)
Leverage Rust's type system - Encode validation rules in types, not handlers

Testing HTMX Handlers

Use the fluent Given-When-Then DSL pattern for acceptance testing HTMX interactions:

Pattern 1: Simple Live Search

Template Setup:

{# search.html #}
<input
    type="text"
    name="q"
    hx-get="/search"
    hx-trigger="keyup changed delay:500ms"
    hx-target="#search-results"
/>
<div id="search-results"></div>

Handler:

#[derive(Deserialize)]
struct SearchParams {
    q: String,
}

#[derive(Template)]
#[template(path = "search_results.html")]
struct SearchResults {
    results: Vec<String>,
}

async fn search(Query(params): Query<SearchParams>) -> impl IntoResponse {
    let results = perform_search(&params.q);
    SearchResults { results }
}

Acceptance Test:

#[tokio::test]
async fn live_search_should_return_matching_results() {
    WebApp::given()
        .a_file_with_content(
            "## TT 2025-01-15\n\
             - #frontend 2h Building search UI\n\
             - #backend 1h Search API\n\
             - #docs 30m Search documentation\n",
        )
        .when_get("/search")
        .with_query("q=search")
        .should_succeed()
        .await
        .expect_status(200)
        .expect_contains("Search API")
        .expect_contains("Search documentation");
}

#[tokio::test]
async fn live_search_should_handle_empty_query() {
    WebApp::given()
        .when_get("/search")
        .with_query("q=")
        .should_succeed()
        .await
        .expect_status(200)
        .expect_not_contains("Search API");
}

Pattern 2: Form Submission with Validation

Template:

<form hx-post="/items" hx-target="#items">
    <input type="text" name="title" required />
    <button type="submit">Add Item</button>
</form>
<div id="items"></div>

Handler:

#[derive(Deserialize)]
struct CreateItem {
    title: String,
}

#[derive(Template)]
#[template(path = "item.html")]
struct ItemTemplate {
    item: Item,
}

async fn create_item(Form(data): Form<CreateItem>) -> impl IntoResponse {
    if data.title.is_empty() {
        return (StatusCode::BAD_REQUEST, "Title required").into_response();
    }

    let item = Item::create(data.title);
    ItemTemplate { item }.into_response()
}

Acceptance Tests:

#[tokio::test]
async fn form_submission_should_create_item() {
    WebApp::given()
        .when_post("/items")
        .with_form_data(&[("title", "New Task")])
        .should_succeed()
        .await
        .expect_status(200)
        .expect_contains("New Task");
}

#[tokio::test]
async fn form_submission_should_reject_empty_title() {
    WebApp::given()
        .when_post("/items")
        .with_form_data(&[("title", "")])
        .should_fail()
        .await
        .expect_status(400)
        .expect_contains("Title required");
}

Pattern 3: Delete with Confirmation

Handler:

async fn delete_item(Path(item_id): Path<String>) -> StatusCode {
    delete_from_database(&item_id);
    StatusCode::OK
}

Acceptance Test:

#[tokio::test]
async fn delete_button_should_remove_item() {
    WebApp::given()
        .a_file_with_content(
            "## TT 2025-01-15\n\
             - #project-alpha 2h Work\n",
        )
        .when_delete("/items/project-alpha")
        .should_succeed()
        .await
        .expect_status(200);
}

Pattern 4: Out-of-Band Updates

Handler returning OOB response:

#[derive(Template)]
#[template(path = "add_to_cart_response.html")]
struct AddToCartResponse {
    notification: String,
    cart_count: usize,
}

async fn add_to_cart(Form(data): Form<AddToCart>) -> impl IntoResponse {
    add_to_cart_db(&data.item_id);
    let count = get_cart_count();

    AddToCartResponse {
        notification: format!("Added {} to cart", data.item_id),
        cart_count: count,
    }
}

Template with OOB:

{# add_to_cart_response.html #}
<!-- Main response -->
<div class="notification">{{ notification }}</div>

<!-- Out-of-band update: cart button elsewhere on page -->
<button id="cart-btn" hx-swap-oob="true">
    Cart ({{ cart_count }})
</button>

Acceptance Test:

#[tokio::test]
async fn add_to_cart_should_update_cart_button() {
    WebApp::given()
        .when_post("/add-to-cart")
        .with_form_data(&[("item_id", "widget-123")])
        .should_succeed()
        .await
        .expect_status(200)
        .expect_contains("Added widget-123 to cart")
        .expect_contains("Cart (1)");  // OOB update verified
}

Pattern 5: Real-time Polling

Handler:

async fn get_stats() -> impl IntoResponse {
    let stats = fetch_current_stats();
    StatsDisplay { stats }
}

Acceptance Test:

#[tokio::test]
async fn stats_endpoint_should_return_current_data() {
    WebApp::given()
        .when_get("/stats")
        .should_succeed()
        .await
        .expect_status(200)
        .expect_contains("Users online")
        .expect_contains("Active sessions");
}

Testing Best Practices

Test the handler, not the JavaScript - HTMX is client-side; your Rust handler only needs to return correct HTML
Use descriptive test names - Name tests after the user-visible behavior ("should update cart button")
Verify HTML response content - Assert the returned template renders with correct data
Test error paths - Verify handlers return appropriate status codes for invalid requests
Test OOB updates - When using out-of-band updates, verify all parts appear in response
Keep tests focused - Each test should verify one interaction pattern

Full Example: Todo App

Templates:

todo_app.html:

<!DOCTYPE html>
<html>
<head>
    <title>Todo App</title>
    <script src="https://unpkg.com/htmx.org@1.9.10"></script>
</head>
<body>
    <div>
        <h1>My Todos</h1>
        <form
            hx-post="/todos"
            hx-target="#todo-list"
            hx-swap="beforeend"
            hx-on::after-request="this.reset()"
        >
            <input
                type="text"
                name="text"
                placeholder="New todo..."
                required
            />
            <button type="submit">Add</button>
        </form>

        <ul id="todo-list">
            {% for todo in todos %}
                <li id="todo-{{ todo.id }}">
                    <input
                        type="checkbox"
                        {% if todo.completed %}checked{% endif %}
                        hx-post="/todos/{{ todo.id }}/toggle"
                        hx-target="#todo-{{ todo.id }}"
                        hx-swap="outerHTML"
                    />
                    <span class="{% if todo.completed %}completed{% endif %}">
                        {{ todo.text }}
                    </span>
                    <button
                        hx-delete="/todos/{{ todo.id }}"
                        hx-target="#todo-{{ todo.id }}"
                        hx-swap="outerHTML swap:500ms"
                    >
                        Delete
                    </button>
                </li>
            {% endfor %}
        </ul>
    </div>
</body>
</html>

Rust implementation:

use axum::{
    extract::{Path, State},
    Form, Router,
    routing::{get, post, delete},
    http::StatusCode,
    response::IntoResponse,
};
use askama::Template;
use serde::Deserialize;
use std::sync::Mutex;

#[derive(Clone)]
struct Todo {
    id: String,
    text: String,
    completed: bool,
}

#[derive(Clone)]
struct AppState {
    todos: std::sync::Arc<Mutex<Vec<Todo>>>,
}

#[derive(Template)]
#[template(path = "todo_app.html")]
struct TodoApp {
    todos: Vec<Todo>,
}

#[derive(Template)]
#[template(path = "todo_item.html")]
struct TodoItem {
    todo: Todo,
}

#[derive(Deserialize)]
struct CreateTodo {
    text: String,
}

async fn list_todos(State(state): State<AppState>) -> impl IntoResponse {
    let todos = state.todos.lock().unwrap().clone();
    TodoApp { todos }
}

async fn create_todo(
    State(state): State<AppState>,
    Form(form): Form<CreateTodo>,
) -> impl IntoResponse {
    let todo = Todo {
        id: uuid::Uuid::new_v4().to_string(),
        text: form.text,
        completed: false,
    };

    state.todos.lock().unwrap().push(todo.clone());
    TodoItem { todo }
}

async fn toggle_todo(
    State(state): State<AppState>,
    Path(id): Path<String>,
) -> impl IntoResponse {
    let mut todos = state.todos.lock().unwrap();
    if let Some(todo) = todos.iter_mut().find(|t| t.id == id) {
        todo.completed = !todo.completed;
        TodoItem { todo: todo.clone() }
    } else {
        StatusCode::NOT_FOUND.into_response()
    }
}

async fn delete_todo(
    State(state): State<AppState>,
    Path(id): Path<String>,
) -> StatusCode {
    let mut todos = state.todos.lock().unwrap();
    todos.retain(|t| t.id != id);
    StatusCode::OK
}

#[tokio::main]
async fn main() {
    let state = AppState {
        todos: std::sync::Arc::new(Mutex::new(vec![])),
    };

    let app = Router::new()
        .route("/todos", get(list_todos).post(create_todo))
        .route("/todos/:id/toggle", post(toggle_todo))
        .route("/todos/:id", delete(delete_todo))
        .with_state(state);

    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
        .await
        .unwrap();

    axum::serve(listener, app).await.unwrap();
}

Resources

Next Steps

Style components → Use CSS frameworks (Tailwind, Bootstrap)
Add state management → Consider database integration
Deploy → Use Docker, Railway, or cloud platforms
Test → Use the WebApp DSL for comprehensive acceptance tests

htmx-rust

HTMX + Axum Integration (Rust)

Overview

When to Use This Skill

Quick Start

1. Add Dependencies

2. Create Base Template (Askama)

3. Create Interactive Component

4. Create Handler

5. Setup Router

Core HTMX Attributes

hx-get / hx-post

hx-target

hx-swap

hx-trigger

Common Patterns

Pattern 1: Live Search

Pattern 2: Infinite Scroll

Pattern 3: Delete with Confirmation

Pattern 4: Inline Edit

Pattern 5: Form Validation

Pattern 6: Polling / Real-time Updates

Advanced Patterns

Out-of-Band Updates (OOB)

Progressive Enhancement

Loading States

Response Headers

HX-Trigger

HX-Redirect

HX-Refresh

Best Practices

Testing HTMX Handlers

Pattern 1: Simple Live Search

Pattern 2: Form Submission with Validation

Pattern 3: Delete with Confirmation

Pattern 4: Out-of-Band Updates

Pattern 5: Real-time Polling

Testing Best Practices

Full Example: Todo App

Resources

Next Steps

HTMX + Axum Integration (Rust)

Overview

When to Use This Skill

Quick Start

1. Add Dependencies

2. Create Base Template (Askama)

3. Create Interactive Component

4. Create Handler

5. Setup Router

Core HTMX Attributes

hx-get / hx-post

hx-target

hx-swap

hx-trigger

Common Patterns

Pattern 1: Live Search

Pattern 2: Infinite Scroll

Pattern 3: Delete with Confirmation

Pattern 4: Inline Edit

Pattern 5: Form Validation

Pattern 6: Polling / Real-time Updates

Advanced Patterns

Out-of-Band Updates (OOB)

Progressive Enhancement

Loading States

Response Headers

HX-Trigger

HX-Redirect

HX-Refresh

Best Practices

Testing HTMX Handlers

Pattern 1: Simple Live Search

Pattern 2: Form Submission with Validation

Pattern 3: Delete with Confirmation

Pattern 4: Out-of-Band Updates

Pattern 5: Real-time Polling

Testing Best Practices

Full Example: Todo App

Resources