Serverless / FaaS
Serverless and FaaS platforms run your code on demand — you ship functions, the platform handles scaling, and you pay nothing while idle.
Serverless (Functions as a Service) flips the hosting model: instead of renting a server that runs around the clock, you deploy individual functions that execute only when triggered. The platform handles provisioning, scaling and tearing down, and because most runtimes scale to zero when idle, the free tiers are measured in invocations rather than uptime. For APIs, webhooks, cron jobs and event handlers, that is an excellent fit.
The category spans two flavors. Edge runtimes like Cloudflare Workers run lightweight code geographically close to users with negligible cold starts, ideal for fast, globally-distributed logic. Traditional FaaS offerings give you fuller language support and longer execution windows, at the cost of slightly higher cold-start latency. Which matters depends on your workload — a user-facing API cares about cold starts, a nightly data job does not.
When weighing free tiers, look at the invocation or request allowance first, then the per-invocation limits on execution time and memory, and finally what state the provider bundles in. Functions are stateless by design, so the real question is often how cheaply you can attach a database, KV store or queue alongside them. Providers that include those primitives on the same free tier let you build a complete backend without stitching together multiple accounts.
Free Serverless / FaaS platforms
FAQ
A cold start is the extra delay when a function runs after being idle and the platform has to spin it up. Edge runtimes like Cloudflare Workers have near-zero cold starts; traditional FaaS may add a few hundred milliseconds. It matters for latency-sensitive APIs, less so for background work.
Choose serverless for spiky, event-driven or low-traffic workloads where scaling to zero saves money. Choose a PaaS when you have a long-running app, persistent connections, or a framework that expects a continuous process.
Not on their own — each invocation is stateless. You attach external state via a database, KV store or object storage, several of which the same providers offer on their free tiers.