| name | trd |
| description | Use when writing Technical Requirements Documents that define how to build a system. Covers system architecture, API specifications, data models, security requirements, performance requirements, dependencies, technical constraints, and deployment plans.
USE FOR: technical design specifications, API contracts, data model documentation, system architecture descriptions, performance and security requirements, deployment plans, infrastructure requirements, technical constraints documentation
DO NOT USE FOR: product-level requirements (use prd), business justification (use brd), recording individual decisions (use adr), executable specs (use gherkin or gauge)
|
| license | MIT |
| metadata | {"displayName":"TRD (Technical Requirements Document)","author":"Tyler-R-Kendrick"} |
| compatibility | claude, copilot, cursor |
| references | [{"title":"Software Requirements Specification — Wikipedia","url":"https://en.wikipedia.org/wiki/Software_requirements_specification"}] |
Technical Requirements Document (TRD)
Overview
A Technical Requirements Document (TRD) defines how a system or feature will be built. It translates the product requirements from the PRD into concrete technical specifications -- architecture, APIs, data models, security controls, performance targets, and deployment strategy. The TRD is the engineering team's blueprint for implementation.
The TRD sits downstream of the PRD and upstream of implementation:
PRD ("What are we building?") --> TRD ("How do we build it?") --> Implementation + ADRs
Standard TRD Structure
1. Title and Metadata
Document identification, ownership, and status tracking.
2. System Overview
High-level description of the system, its purpose, and how it fits into the broader architecture.
3. Architecture
System architecture including components, interactions, technology stack, and diagrams.
4. API Specifications
Endpoints, request/response schemas, authentication, error handling, and versioning.
5. Data Models
Database schema, entity relationships, data types, constraints, and migration strategy.
6. Security Requirements
Authentication, authorization, encryption, compliance, and threat model.
7. Performance Requirements
Latency, throughput, availability, and scalability targets.
8. Dependencies
External services, libraries, infrastructure, and team dependencies.
9. Technical Constraints
Technology mandates, backward compatibility, regulatory, and organizational constraints.
10. Deployment Plan
Environments, CI/CD pipeline, rollout strategy, and rollback procedures.
Complete TRD Template
# TRD: [System/Feature Name]
| Field | Value |
|------------------|--------------------------------|
| Author | [Name] |
| Status | Draft / In Review / Approved |
| Created | YYYY-MM-DD |
| Last Updated | YYYY-MM-DD |
| PRD Reference | [Link to PRD] |
| Reviewers | [Names] |
| Approvers | [Names] |
## 1. System Overview
### 1.1 Purpose
[Brief description of what this system does and why it exists.
Reference the PRD for product context.]
### 1.2 Scope
[What is covered by this TRD. What is explicitly excluded.]
### 1.3 Context
[How this system fits into the broader architecture.
Include a C4 Context diagram or equivalent.]
```mermaid
graph LR
User[End User] --> WebApp[Web Application]
WebApp --> API[API Gateway]
API --> AuthService[Auth Service]
API --> OrderService[Order Service]
OrderService --> Database[(PostgreSQL)]
OrderService --> MessageQueue[RabbitMQ]
MessageQueue --> NotificationService[Notification Service]
2. Architecture
2.1 Architecture Style
[Monolith / Microservices / Serverless / Event-driven / Hybrid]
[Justification for the chosen approach. Link to ADR if applicable.]
2.2 Component Overview
| Component | Responsibility | Technology |
|---|
| API Gateway | Request routing, rate limiting, auth | [e.g., Kong] |
| Auth Service | Authentication, token management | [e.g., .NET 8] |
| Order Service | Order lifecycle management | [e.g., .NET 8] |
| Notification Service | Email, SMS, push notifications | [e.g., Node.js] |
| Database | Persistent data storage | [e.g., PostgreSQL] |
| Message Queue | Async event processing | [e.g., RabbitMQ] |
2.3 Technology Stack
| Layer | Technology | Version |
|---|
| Frontend | [e.g., React, Blazor] | [version] |
| Backend API | [e.g., ASP.NET Core, Express] | [version] |
| Database | [e.g., PostgreSQL, SQL Server] | [version] |
| Cache | [e.g., Redis] | [version] |
| Message Broker | [e.g., RabbitMQ, Kafka] | [version] |
| Hosting | [e.g., Azure AKS, AWS ECS] | N/A |
2.4 Communication Patterns
| From | To | Protocol | Pattern |
|---|
| Web App | API Gateway | HTTPS | Synchronous |
| API Gateway | Auth Service | gRPC | Synchronous |
| API Gateway | Order Service | HTTPS/REST | Synchronous |
| Order Service | Notification Service | AMQP | Async (event) |
3. API Specifications
3.1 API Design Principles
[REST / GraphQL / gRPC. Versioning strategy. Naming conventions.]
3.2 Authentication and Authorization
[OAuth 2.0, JWT, API keys. Token format and validation. Scope/role model.]
3.3 Endpoints
POST /api/v1/orders
Description: Create a new order
Authentication: Bearer token (JWT)
Authorization: Role: customer
Request:
{
"items": [
{
"productId": "WM001",
"quantity": 2
}
],
"shippingAddress": {
"street": "123 Main St",
"city": "Springfield",
"state": "IL",
"zip": "62701"
},
"paymentMethodId": "pm_abc123"
}
Response (201 Created):
{
"orderId": "ord_789xyz",
"status": "pending",
"total": 59.98,
"currency": "USD",
"estimatedDelivery": "2025-02-15",
"createdAt": "2025-02-08T14:30:00Z"
}
Error Responses:
| Status | Code | Description |
|---|
| 400 | INVALID_REQUEST | Missing or malformed fields |
| 401 | UNAUTHORIZED | Invalid or expired token |
| 403 | FORBIDDEN | Insufficient permissions |
| 409 | OUT_OF_STOCK | Requested quantity unavailable |
| 422 | VALIDATION_ERROR | Business rule violation |
| 500 | INTERNAL_ERROR | Unexpected server error |
3.4 Rate Limiting
[Requests per minute per user/IP. Rate limit headers. Retry-After behavior.]
3.5 Pagination
[Cursor-based / offset-based. Page size limits. Response envelope format.]
4. Data Models
4.1 Entity-Relationship Diagram
erDiagram
User ||--o{ Order : places
Order ||--|{ OrderItem : contains
OrderItem }o--|| Product : references
Order ||--o| Payment : "paid by"
User ||--o{ Address : has
4.2 Schema Definitions
Users Table
| Column | Type | Constraints | Description |
|---|
| id | UUID | PK | Unique identifier |
| email | VARCHAR(255) | UNIQUE, NOT NULL | Login email |
| password_hash | VARCHAR(255) | NOT NULL | Bcrypt hash |
| created_at | TIMESTAMPTZ | NOT NULL, DEFAULT NOW | Account creation time |
| updated_at | TIMESTAMPTZ | NOT NULL | Last modification |
Orders Table
| Column | Type | Constraints | Description |
|---|
| id | UUID | PK | Unique identifier |
| user_id | UUID | FK -> Users(id) | Customer reference |
| status | VARCHAR(50) | NOT NULL | Order status enum |
| total | DECIMAL(10,2) | NOT NULL | Order total amount |
| currency | CHAR(3) | NOT NULL, DEFAULT 'USD' | ISO 4217 currency |
| created_at | TIMESTAMPTZ | NOT NULL, DEFAULT NOW | Order creation time |
4.3 Data Migration Strategy
[How schema changes are applied. Tool (e.g., Flyway, EF Migrations).
Backward compatibility during rolling deployments.]
4.4 Data Retention and Archival
[Retention policies. PII handling. Archival strategy for historical data.]
5. Security Requirements
5.1 Authentication
[Mechanism: OAuth 2.0 + PKCE, JWT tokens, session management.
Token lifetime and refresh strategy.]
5.2 Authorization
[RBAC / ABAC model. Role definitions. Permission matrix.]
| Role | Create Order | View Orders | Cancel Order | Admin Panel |
|---|
| Customer | Yes | Own only | Own (pending) | No |
| Support | No | All | All | No |
| Admin | Yes | All | All | Yes |
5.3 Data Protection
[Encryption at rest (AES-256). Encryption in transit (TLS 1.2+).
PII handling. GDPR/CCPA compliance measures.]
5.4 Input Validation
[Validation strategy. Sanitization. SQL injection prevention.
XSS prevention. CSRF protection.]
5.5 Secrets Management
[Vault / Key Vault / SSM. Secret rotation policy.
No secrets in code or environment files.]
5.6 Audit Logging
[What is logged. Log retention. Tamper-proof storage.]
6. Performance Requirements
6.1 Latency Targets
| Operation | P50 Target | P95 Target | P99 Target |
|---|
| API response | < 100ms | < 300ms | < 1s |
| Page load (FCP) | < 1.5s | < 3s | < 5s |
| Search results | < 200ms | < 500ms | < 2s |
| Order placement | < 500ms | < 1s | < 3s |
6.2 Throughput
[Expected RPS. Peak load projections. Burst capacity.]
6.3 Availability
[SLA target (e.g., 99.9%). Planned maintenance windows.
Failover strategy. RTO and RPO.]
6.4 Scalability
[Horizontal vs vertical scaling strategy.
Auto-scaling triggers and limits.
Database read replicas / sharding plan.]
6.5 Caching Strategy
[Cache layers (CDN, application cache, database cache).
Cache invalidation strategy. TTL policies.]
7. Dependencies
7.1 External Services
| Service | Purpose | SLA | Fallback Strategy |
|---|
| [Payment Provider] | Payment processing | 99.95% | Queue and retry |
| [Email Provider] | Transactional email | 99.9% | Fallback provider |
| [CDN Provider] | Static asset delivery | 99.99% | Origin fallback |
7.2 Internal Dependencies
[Other team services, shared libraries, platform services.]
7.3 Third-Party Libraries
[Key libraries with versions. License compliance. Update strategy.]
8. Technical Constraints
- [Constraint 1: e.g., Must run on .NET 8 LTS]
- [Constraint 2: e.g., Must use PostgreSQL (organizational standard)]
- [Constraint 3: e.g., Must support IE 11 (legacy customer requirement)]
- [Constraint 4: e.g., Must integrate with existing SSO via SAML 2.0]
- [Constraint 5: e.g., Maximum deployment artifact size 500MB]
9. Deployment Plan
9.1 Environments
| Environment | Purpose | URL |
|---|
| Development | Active development | dev.example.internal |
| Staging | Pre-production testing | staging.example.internal |
| Production | Live traffic | api.example.com |
9.2 CI/CD Pipeline
[Build → Test → Security Scan → Deploy → Smoke Test → Rollout]
[Tool: GitHub Actions / Azure DevOps / Jenkins]
9.3 Rollout Strategy
[Blue-green / Canary / Rolling update.
Canary percentage and promotion criteria.
Feature flags for gradual rollout.]
9.4 Rollback Plan
[Automated rollback triggers (error rate, latency).
Manual rollback procedure.
Database rollback strategy (backward-compatible migrations).]
9.5 Monitoring and Alerting
[Metrics: latency, error rate, CPU, memory, queue depth.
Tools: Prometheus, Grafana, Datadog, Azure Monitor.
Alert thresholds and escalation policy.]
10. Open Technical Questions
Appendix
A. Glossary
[Domain-specific technical terms and acronyms.]
B. Related Documents
- PRD: [link]
- ADRs: [links to relevant architecture decisions]
- API Schema: [link to OpenAPI/Swagger spec]
- Runbook: [link to operational runbook]
## TRD Example: Order Service
```markdown
# TRD: Order Service
| Field | Value |
|------------------|---------------------------|
| Author | Jane Engineer |
| Status | In Review |
| Created | 2025-01-15 |
| PRD Reference | PRD-042: Checkout Redesign|
## 1. System Overview
The Order Service manages the complete order lifecycle from creation
through fulfillment. It replaces the order module in the monolith
as part of the microservices migration (see ADR-007).
## 2. Architecture
Architecture style: Event-driven microservice (see ADR-012).
The service exposes a REST API for synchronous order operations
and publishes domain events to RabbitMQ for downstream consumers
(notification, analytics, fulfillment).
## 3. Key API Endpoints
- POST /api/v1/orders -- Create order
- GET /api/v1/orders/{id} -- Get order by ID
- GET /api/v1/orders?userId={id} -- List user orders
- PATCH /api/v1/orders/{id}/cancel -- Cancel order
- POST /api/v1/orders/{id}/refund -- Initiate refund
## 4. Data Model
Orders table with OrderItems join table. Uses PostgreSQL with
EF Core migrations. See schema definitions in Section 4.2 above.
## 5. Events Published
| Event | Trigger | Consumers |
|--------------------|-----------------------|----------------------------|
| OrderCreated | New order placed | Notification, Analytics |
| OrderCancelled | Order cancelled | Notification, Fulfillment |
| OrderFulfilled | Order shipped | Notification, Analytics |
| PaymentProcessed | Payment confirmed | Order (self), Analytics |
Relationship to Other Documents
BRD (Business Requirements)
| Business case and justification
v
PRD (Product Requirements)
| What to build, user stories, success metrics
v
TRD (Technical Requirements) <-- YOU ARE HERE
| How to build it -- architecture, APIs, data, deployment
|
+---> ADR (Architecture Decision Records)
| Individual decisions made during TRD creation
| (e.g., "Why PostgreSQL over MongoDB?")
|
+---> RFC (Request for Comments)
| Proposals for significant technical changes
| that need team-wide input before finalizing
|
v
Implementation
| Code guided by the TRD
v
Gherkin / Gauge (Executable Specs)
Verification that implementation meets requirements
Best Practices
- Reference the PRD -- every technical decision should trace back to a product requirement. If a TRD section cannot be justified by the PRD, question whether it belongs.
- Include diagrams -- architecture diagrams (C4, sequence, ERD) communicate structure far better than prose alone. Use Mermaid for Markdown-native rendering.
- Specify API contracts precisely -- include request/response schemas, error codes, authentication, pagination, and rate limiting. Consider providing an OpenAPI spec as an appendix.
- Define performance targets with percentiles -- P50, P95, and P99 targets are more useful than averages, which hide tail latency.
- Document the security model explicitly -- authentication, authorization, encryption, input validation, and secrets management deserve dedicated sections, not afterthoughts.
- Plan for failure -- include rollback procedures, circuit breaker strategies, fallback behaviors, and disaster recovery in the deployment plan.
- Record decisions as ADRs -- when the TRD makes a significant technical choice (database, framework, architecture style), create a linked ADR to capture the context and trade-offs.
- Keep it current -- update the TRD as the system evolves. An outdated TRD is a liability, not an asset.
- Review with the full engineering team -- the TRD should be reviewed by backend, frontend, infrastructure, security, and QA engineers before implementation begins.
- Use version control -- store the TRD in the repository alongside the code it describes so it evolves with the system.
