Directory / Fern
Fern
Verified
OpenAPI-to-SDKs and docs, an alternative to Stainless.
Fern generates SDKs and documentation from API definitions. Same factory job as Stainless: make the contract executable so agents do not invent clients. Listed separately because it is a different company and domain.
- Model independence
- Multi-model
- Deployment
- Cloud, Self-hosted
- Open source
- Yes
- License
- See repository (open-core)
- Pricing model
- Mixed
- Added / updated
- 19 Aug 2026 / 19 Aug 2026
buildwithfern.com · Docs · Source
Editorial take
Fern vs Stainless is a procurement choice. We will not pick a winner. Open-core vs closed is the structural difference worth reading. Still not a general coding agent.
Strengths
- Spec-driven SDK/docs generation.
- Public repo / open-core path.
- Keeps agents away from hand-rolled clients.
Limitations
- Same narrow job as Stainless.
- Open-core license split.
- Spec quality is the real product.