Cloudflare Workers - Serverless Functions That Actually Start Fast

Lambda cold starts are fucking painful - sometimes you wait 500ms+ just for your function to wake up, and that's if you're lucky. I've debugged enough production incidents at 3am to know that cold start latency kills user experience faster than anything else.

Workers solved this by ditching containers entirely. Instead of spinning up a new container for every request like Lambda does, Workers use V8 isolates - the same isolation tech that lets Chrome run untrusted JavaScript safely. Your code runs in milliseconds because it's not waiting for an entire container to boot up.

Why This Actually Matters in Production

I've run Workers in production for two years now, and the cold start difference is genuinely night and day. Lambda can take anywhere from 100ms to 1000ms to start (Node.js is especially brutal), while Workers start basically instantly. The performance benchmark numbers are real - I consistently see sub-10ms cold starts.

This isn't just academic. When you're serving API requests or handling webhook events, that 500ms Lambda cold start adds up fast. Users notice it, monitoring alerts fire, and you spend your weekend debugging why your "fast" API is slow as hell.

Workers deploy everywhere automatically - all 330+ locations without you doing anything. Lambda makes you pick regions and manage deployments. It's the difference between "just works globally" and "spend three hours configuring regions."

The Pricing Actually Makes Sense

Lambda bills you for wall-clock time - even when your function is sitting there waiting for a database query to return. Workers bill you for CPU time only. If your function spends 90% of its time waiting for I/O (database calls, API requests), you only pay for the 10% when it's actually doing work.

I've seen AWS bills drop by 40% just from switching I/O-heavy workloads from Lambda to Workers. The free tier is generous too: 100,000 requests per day and 10ms CPU time per request.

What You Can Actually Build

Workers started as simple edge functions but now handle full-stack apps. You can run React, Next.js, FastAPI - whatever. The JavaScript ecosystem works, Python is in beta, and anything that compiles to WebAssembly runs fine.

The database story is solid: D1 SQLite for edge-native storage, Hyperdrive for connection pooling to external databases, and KV storage for caching. Durable Objects give you stateful logic when you need it.

The Sharp Edges Nobody Mentions

Workers aren't perfect. You get 128MB of memory and 30 seconds max execution time (5 minutes if you pay more). No filesystem access, limited Node.js APIs. If you're doing heavy CPU work or need to process large files, stick with Lambda or containers.

The local dev environment doesn't perfectly match production. I've hit edge cases where code works locally but fails on the edge. The debugging story is getting better with Workers Observability, but it's still not as mature as CloudWatch.

Workers is genuinely fast and the pricing makes sense, but it's not a drop-in replacement for everything. Know the limitations before you migrate your entire backend.

Full-Stack Apps That Don't Suck

I've been running full-stack Next.js apps on Workers since they added framework support. The React Router integration actually works - no more fighting with edge runtime compatibility hell.

The big shift happened when they let you deploy your entire app stack in one place. Static files serve from the edge, API routes run as Workers, and your database sits right there too. It's not revolutionary, but it eliminates the usual serverless architecture headaches.

Database Story That Doesn't Completely Blow

D1 (their SQLite offering) works well if you can live with SQLite's limitations. I use it for session storage and small datasets. The global read replication is legit - queries actually run locally instead of round-tripping to some distant database.

For real databases, Hyperdrive connection pooling to PostgreSQL has been solid. No more connection pool exhaustion killing my API at 2am. Works with Prisma and Drizzle without fighting the ORM.

The vector database (Vectorize) is decent for basic semantic search, but if you're doing heavy ML workloads, you'll hit the memory limits fast.

AI Integration Reality Check

Workers AI gives you access to models without managing infrastructure. I've used it for content moderation and basic text processing. It's convenient but not groundbreaking - still cheaper than spinning up your own inference servers.

The AI Gateway is actually useful for rate limiting and cost control when you're hitting multiple AI APIs. Saved my ass when a runaway script was burning through OpenAI credits.

The AutoRAG stuff is new, haven't battle-tested it in production yet.

Real-Time Apps Without WebSocket Hell

Durable Objects solve the "where does my stateful shit live?" problem. I built a collaborative editor that needed to coordinate document state - Durable Objects handle it without me thinking about which server holds what.

Each object runs in one location but clients can hit it from anywhere. Latency isn't perfect but it beats managing your own stateful service mesh.

The new Realtime SDK looks promising for WebRTC apps, but I haven't had a chance to break it yet.

Production War Stories

Our API gateway replacement has been running on Workers for 8 months. Handles authentication, rate limiting, and request routing. Zero downtime incidents so far, which is more than I can say for our old Kong setup.

A/B testing is where Workers really shine - you can deploy experiments instantly without cache invalidation bullshit. No more waiting 5 minutes to see if your feature flag actually worked.

Bot protection runs in real-time before requests hit your origin. Caught a bunch of scraping attempts that would have killed our database.

Enterprise Stuff That Actually Works

The new secrets management is in beta but works better than storing secrets in environment variables like a caveman. Role-based access control prevents junior devs from accidentally exposing production keys.

Workers Logs with the query builder helps debug edge logic. The error messages still suck but you can actually find what broke at 3am.

Smart Placement automatically moves your Workers closer to your data sources based on traffic patterns. Haven't noticed dramatic improvements but it's one less thing to think about.

What's Coming That Might Not Suck

Container support is coming mid-2025. If it works as advertised, you could migrate existing Docker apps to the edge without rewriting everything. Big if though - edge containers are hard to get right.

Workers went from "Lambda but faster" to a legitimate platform for building distributed apps. The cold start advantage is real, the integrated services mostly work, and the global deployment model eliminates a lot of infrastructure complexity.

Is it perfect? Fuck no. But it's good enough that I choose it for new projects instead of cobbling together AWS services.