Fern
Turns an API spec into SDKs, a docs site and an MCP server without hand-written glue.
why this verdict
Downgrade — pay for the workflow, not the AI
Speakeasy and Scalar cover the headline feature free, so the $250/mo is now paying for the workflow around it.
- A named launch, not a vibe named, unlinked
- GPT-5 producing SDK code and reference docs from a spec in a single pass. OpenAI, August 7, 2025 — no announcement link recorded yet.
- How much of the job it covers headline only editorial call
- The headline feature, but not the workflow, data or integrations around it.
- Is there a free way to do it? yes
- 3 of 3 listed replacements have a usable free tier: Speakeasy, Scalar and Redocly.
- What the call is worth $3,000/yr
- $250/mo at the entry paid tier — $3,000 a year per seat.
- Threatened by
- OpenAI
- Since
- August 7, 2025
- List price
- $250/mo
- Per year
- $3,000
The backstory
Fern generates client libraries and a polished documentation site from an OpenAPI or gRPC definition, and now also emits MCP servers so agents can call the API. Frontier models will write a serviceable client from the same spec for free, which caps what small teams will pay. The competitive picture also shifted when Stainless wound down after its team joined Anthropic. Fern keeps real value in ongoing publishing, versioning and the docs product, so it is pressured rather than finished.
Escape hatches
switching could free up $3,000/yrSDK generation with strong multi-language maintenance tooling
speakeasy.com open_in_newOpen-source API reference and client from OpenAPI
scalar.com open_in_newOpenAPI linting, docs and developer portal tooling
redocly.com open_in_new3 of 3 replacements have a usable free tier.
