Last updated 06-28-2026
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Stainless
Stainless is a developer platform that turns an OpenAPI spec into idiomatic client libraries, API documentation, and MCP servers for coding agents. API teams at companies like OpenAI, Anthropic, and Cloudflare used it to ship Stripe-quality SDKs in TypeScript, Python, Go, Java, Ruby, and more without hand-maintaining every language. In May 2026, Stainless announced it is joining Anthropic and winding down hosted products, so new signups and projects are no longer available.
The platform was built by engineers behind Stripe's internal code generation. You point Stainless at your OpenAPI spec, it generates a config for pagination and auth, and outputs libraries with rich types, auto-pagination, retries, streaming, webhooks, and file uploads. Custom edits persist across regenerations, and GitHub workflows can open PRs when your spec changes.
Beyond SDKs, Stainless also ships a Docs Platform on Astro and code-mode MCP servers that expose search_docs and execute tools so agents write typed SDK code instead of loading hundreds of endpoint schemas. API platform teams, developer relations engineers, and backend leads used it to keep public interfaces consistent as APIs evolve.
Generates SDKs for TypeScript, Python, Go, Java, Kotlin, Ruby, Terraform, C#, and PHP
Built-in streaming, webhooks, file uploads, and auto-pagination from your OpenAPI spec
Custom code edits survive the next regeneration cycle
Docs Platform keeps REST, SDK, and narrative docs in sync on Astro
MCP Code Mode uses search_docs and execute instead of one tool per endpoint
GitHub workflows regenerate SDKs and open PRs when your spec changes
Generates idiomatic multi-language SDKs from a single OpenAPI spec with types and pagination baked in.
Customers retain ownership of generated SDK code published under Apache 2.0.
MCP Code Mode keeps agent context small on APIs with hundreds of endpoints.
Free tier includes up to 5 generators and 25 endpoints for early testing.
Hosted Stainless products are winding down after the Anthropic acquisition, with no new signups.
Starter, Pro, and Enterprise prices are not listed publicly on the pricing page scrape.
GitHub account is required for authentication and staging repository access.
Code generation cannot be hosted on-premise; only the OpenAPI spec is shared with Stainless.
Does Stainless have a free plan?
Yes. Stainless offers a Free plan at $0 with up to 5 generators (each SDK, docs site, or MCP server counts as one), 5 seats, and APIs with up to 25 endpoints. Exceeding the Free plan enrolls you in a 30-day trial of a paid plan per stainless.com pricing.
What languages does Stainless support for SDK generation?
Stainless generates client libraries for TypeScript, Python, Go, Java, Kotlin, Ruby, Terraform, C#, and PHP. The SDK product page describes them as idiomatic libraries with rich types, auto-pagination, and retries out of the box.
Is Stainless still accepting new customers?
No. Stainless announced in May 2026 that it is joining Anthropic and winding down hosted products, including the SDK generator. New signups, projects, and SDKs are not available; existing customers can use app.stainless.com/transition for migration help.
Do I need a GitHub account to use Stainless?
Yes. Stainless requires a GitHub account for authentication and access to staging repositories it generates for customers. A personal GitHub account works and does not need to belong to a company organization.
What happens to my SDKs if I cancel Stainless?
You own the generated SDK code. Stainless publishes it under the Apache 2.0 license. If you stop using Stainless, you can keep using existing code, but Stainless will no longer publish OpenAPI and security updates to your SDKs.
How does Stainless MCP Code Mode work?
Stainless MCP servers expose two tools: search_docs for API reference lookup and execute for running TypeScript against your generated SDK in a sandbox. Agents write SDK code directly instead of loading one schema per endpoint, which Stainless says cuts tool calls and token use on large APIs.