Fern vs Stainless
Fern
buildwithfern.com
Stainless
stainless.comSide by side
| Figure | Fern | Stainless |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | Yes |
| Open source | Yes | — |
| Web | Yes | Yes |
| Windows | Yes | — |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| API | Yes | — |
| Self-hosted | Yes | — |
| Plans published | 2 | 1 |
| Spec score · API Generation Software | 9.0 (#1) | 7.5 (#14) |
| Spec score · Code Generators | 9.0 (#2) | 7.4 (#25) |
| Spec score · Developer Documentation Software | 8.7 (#5) | 7.4 (#20) |
| SDK languages | SDK generation supports TypeScript, Python, Go, Java, C#, PHP, Ruby, Swift, and Rust. | Its SDK product lists TypeScript, Python, Go, Java, Kotlin, Ruby, Terraform, C#, and PHP. |
| Security | Fern's trust center lists SOC 2 Type II, GDPR, and CCPA and provides access requests for its SOC 2 report, penetration test summary, and information security policy. | Stainless says Business and Enterprise customers can request its SOC 2 compliance report. |
| Support | The Enterprise plan includes dedicated support and an uptime SLA. | The pricing page lists email support for the Free plan. |
| What it does | Fern turns API definitions and Markdown into hosted documentation sites, SDKs, and command-line tools. | Stainless generates SDKs, documentation, and MCP servers from an OpenAPI specification. |
Plans
In their own words
Stainless
Stainless generates SDKs, documentation and MCP servers from OpenAPI specifications. Its SDK product lists TypeScript, Python, Go, Java, Kotlin, Ruby, Terraform, C# and PHP, with rich types, automatic pagination and retries included. The Docs Platform, built on Astro, keeps REST API, SDK and narrative documentation in sync with an API. Its listed features include AI-powered hybrid search, Markdown copying, AI-tool integration, and light and dark modes. Stainless also generates code-mode MCP servers so agents can work with SDKs and documentation rather than many endpoint schemas; the MCP product page names Claude Code and Cursor as clients. The Free plan costs nothing and allows up to five generators, five seats and 25 endpoints, with 100 preview builds per month and a rate limit of 25 per day. Email support is listed for Free. Users need a GitHub account for authentication and access to generated staging repositories. Exceeding Free plan terms triggers automatic enrollment in a 30-day free trial of a paid plan. Code generation cannot be hosted on-premise, although generated SDKs can be hosted in a private GitHub repository.