customerio-rate-limits

name	customerio-rate-limits
description	Implement Customer.io rate limiting and backoff. Use when handling high-volume API calls, implementing retry logic, or hitting 429 errors. Trigger: "customer.io rate limit", "customer.io throttle", "customer.io 429", "customer.io backoff", "customer.io too many requests".
allowed-tools	Read, Write, Edit, Bash(npm:*), Bash(npx:*), Glob, Grep
version	1.14.0
license	MIT
author	Jeremy Longshore <[e-mail]>
tags	["saas","customer-io","api","rate-limiting"]
compatibility	Designed for Claude Code

Customer.io Rate Limits

Overview

Understand Customer.io's API rate limits and implement proper throttling: token bucket limiters, exponential backoff with jitter, queue-based processing, and 429 response handling.

Rate Limit Reference

API	Endpoint	Limit	Scope
Track API	identify, track, trackAnonymous	~100 req/sec	Per workspace
Track API	Batch operations	~100 req/sec	Per workspace
App API	Transactional email/push	~100 req/sec	Per workspace
App API	Broadcasts, queries	~10 req/sec	Per workspace

These are approximate. Customer.io uses sliding window rate limiting. When exceeded, you get a 429 Too Many Requests response.

Instructions

Step 1: Token Bucket Rate Limiter

// lib/rate-limiter.ts
export class TokenBucket {
  private tokens: number;
  private lastRefill: number;

  constructor(
    private readonly maxTokens: number = 80,  // Stay under 100/sec limit
    private readonly refillRate: number = 80   // Tokens per second
  ) {
    this.tokens = maxTokens;
    this.lastRefill = .();
  }

   ():  {
     now = .();
     elapsed = (now - .) / ;
    . = .(., . + elapsed * .);
    . = now;
  }

   (): <> {
    .();
     (. >= ) {
      . -= ;
      ;
    }
    
     waitMs = (( - .) / .) * ;
      ( (r, .(waitMs)));
    . = ;
    . = .();
  }
}