API Rate Limiting and Caching Strategies
Protect your backend and cut costs by implementing rate limiting to stop abuse and caching layers that reduce redundant work and speed up responses.
API Rate Limiting and Caching Strategies is a free Indie Hacker Mobile Apps lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Indie Hacker Mobile Apps learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Why Limit and Cache
As your app grows, two problems appear: abusive or runaway clients hammering your API, and the same expensive work repeated needlessly. Rate limiting and caching solve both.
Together they protect uptime and slash costs.
What Is Rate Limiting?
Rate limiting caps how many requests a client can make in a window — for example 100 requests per minute. Beyond that, requests are rejected or delayed.
It defends against abuse, bugs, and accidental loops.
The Token Bucket
A common algorithm is the token bucket: each request consumes a token; tokens refill at a steady rate. When the bucket is empty, requests are throttled.
let tokens = 5;
function allowRequest() {
if (tokens > 0) { tokens--; return true; }
return false;
}
console.log(allowRequest());
console.log(allowRequest());Communicating Limits
Good APIs return headers like X-RateLimit-Remaining and a 429 Too Many Requests status with a Retry-After hint.
This lets well-behaved clients back off gracefully.
What Is Caching?
Caching stores the result of expensive work so repeat requests return instantly without recomputing or re-fetching.
A cache hit saves database load, compute, and time.
Cache Keys and TTL
Each cached entry has a key identifying the request and a TTL (time to live) after which it expires and is refreshed.
const cache = new Map();
function setCache(key, value, ttlMs) {
cache.set(key, { value, expires: Date.now() + ttlMs });
}
setCache('user:1', { name: 'Alice' }, 60000);
console.log(cache.get('user:1'));Cache Layers
Caching happens at multiple levels:
- Client: in-app cache
- CDN: at the edge near users
- Server: in-memory or Redis
Each layer cuts work from the one below it.
Cache Invalidation
The hard part: stale data. When the underlying data changes, the cache must be invalidated or it serves outdated results.
Strategies include short TTLs, event-based invalidation, and versioned keys.
What Not to Cache
Avoid caching:
- Highly personalized or sensitive data without scoping by user
- Rapidly changing values where staleness misleads
Cache what is read often and changes rarely.
Combining the Two
Rate limiting and caching reinforce each other. Caching reduces how often you hit the limit, and limits protect uncached, expensive endpoints from abuse.
Apply both per endpoint based on cost and sensitivity.
A Protection Checklist
Before scaling:
- Rate limit per user and per IP
- Return 429 with Retry-After
- Cache hot, slow-changing reads with sensible TTLs
- Plan invalidation up front
- Never cache sensitive data unscoped
Resilient and cheap to run.
Quick Check
Test your rate limiting and caching knowledge.
Recap
You learned to protect and speed up your backend:
- Rate limiting caps requests and defends against abuse
- Token bucket is a common algorithm; return 429 with Retry-After
- Caching stores expensive results across client, CDN, and server
- Use TTLs and plan invalidation to avoid stale data
- Combine both per endpoint by cost and sensitivity
Resilient, fast, and cheap to operate.
Frequently asked questions
Is the “API Rate Limiting and Caching Strategies” lesson free?
Yes — the full text of “API Rate Limiting and Caching Strategies” is free to read here on the web, and the Indie Hacker Mobile Apps course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Indie Hacker Mobile Apps course, upgrade to CoddyKit PRO.
What will I learn in “API Rate Limiting and Caching Strategies”?
Protect your backend and cut costs by implementing rate limiting to stop abuse and caching layers that reduce redundant work and speed up responses. You practise Indie Hacker Mobile Apps with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Indie Hacker Mobile Apps?
No prior experience is required. Indie Hacker Mobile Apps on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “API Rate Limiting and Caching Strategies” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Indie Hacker Mobile Apps lesson?
Yes. Every Indie Hacker Mobile Apps lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Optimizing BaaS for Performance
- Custom Backend Integrations
- Mobile App Security Best Practices
- API Rate Limiting and Caching Strategies