greatapis
A field guide to the programmable web.
What problem does it solve?
Free tiers and APIs are scattered across docs and pricing pages, so it's hard to discover what exists and how to authenticate before committing.
Who is it for?
Developers integrating third-party services who want to find and compare APIs fast.
Why did we build it?
FreeTier answered "what's free" but not "what APIs even exist and how do I authenticate against them" — that's a different, harder discovery problem, and we kept solving it manually for client integrations.
GreatAPIs is the sibling product: a directory of 1,500+ APIs across 51 categories, built so the auth model and readiness of an API — not just its existence — is visible before you commit to integrating it.
How does it work?
- Auth type as a first-class filter
Every API is tagged by auth type — none, API key, or OAuth — because that's usually the first blocker in an integration, not an afterthought.
- HTTPS and CORS readiness flags
Each entry flags whether the API is HTTPS-only and CORS-ready, surfacing the two checks that otherwise only show up once you've already started wiring the integration.
- 1,500+ APIs across 51 categories
Coverage spans well beyond AI/dev tooling, organised by category so the directory is a discovery tool, not just a long flat list.
What's the hard part?
Consistency at 1,500+ entries is the hard part — auth models, HTTPS support, and CORS behaviour all have to be verified per API rather than assumed from documentation, since docs and reality drift, especially for smaller or less-maintained APIs.
What does it do?
- Curated directory of 1,500+ APIs across 51 categories
- Filter by auth type — None, API Key, or OAuth
- HTTPS and CORS readiness flags per API
- Sibling to freetier.co, not limited to free offerings
What does this prove we can do for you?
Evaluating an API's auth model and integration readiness before committing to it is exactly the due-diligence step we run before wiring any third-party service into a client's stack.
Where this shows up in client work
Questions, answered.
The questions we get asked most, answered plainly: no hedging, no marketing copy.
01 How is GreatAPIs different from FreeTier?
FreeTier is about what's free; GreatAPIs is about what exists and how to authenticate against it, across a much wider set of APIs — free or not.
02 What does the auth-type filter cover?
None, API key, or OAuth — so you can filter to what your stack can actually support before evaluating anything else.
03 Are the HTTPS/CORS flags kept current?
They're checked against each API directly rather than inferred from documentation, since docs and real behaviour can drift.
A curated directory of 1,500+ APIs across 51 categories, with auth type and HTTPS/CORS readiness flagged for each — find and compare APIs fast.
This is the same discipline, real architecture decisions and an honest account of the hard part, that we bring to client engagements.