For Stainless customers
Migrate from Stainless to APIMatic, the original CodeGen
Your Stainless SDKs are yours to keep. APIMatic helps you keep the pipeline that maintains them — SDKs, docs, MCP servers, and CLIs generated from one OpenAPI spec. Free migration assessment, plus 50% off your first year, for paying Stainless customers.
Your generated SDK code — yours to modify, relicense, fork, or maintain independently
Your stainless.yaml config files — yours to keep (though they only operate with Stainless tooling)
Your published packages on npm, PyPI, Maven, and other registries — already live in the ecosystem
Auto-regeneration when your OpenAPI spec changes — every API change becomes a manual port across every SDK language
Package publishing pipeline — no more automated releases to npm, PyPI, Maven, NuGet on merge
Support and accountability — there's no SDK platform team to file issues against
Stainless's transition guide suggests three paths if you want to maintain your SDKs without a managed platform. All three work — here's what they cost in practice.
| Path | Where it fits | What to plan for |
|---|---|---|
| Manual maintenance | Small APIs, 1–2 SDK languages | 0.5–1.5 FTE of senior engineering time; cross-language drift; single-person dependency |
| Agentic coding tools (Claude Code Actions, Cursor, etc.) | One-shot edits to a single SDK at a time | Cross-language consistency; custom-code preservation across regenerations; senior review per PR; no SLA when output breaks production |
| Open-source generators (TypeSpec, OpenAPI Generator) | Teams with strong internal build-engineering capacity | Functional but less idiomatic output; limited customization vs. a managed platform; ongoing maintenance of the generator integration in your build |
Generate SDKs, docs, MCP servers, and CLIs from a single OpenAPI spec — with the auto-regeneration, custom-code preservation, and publishing pipeline you had with Stainless.
Idiomatic SDKs in each language. Auto-regenerated when your OpenAPI spec changes. Published to npm, PyPI, Maven, etc.
TSPythonJavaC#RubyPHP
Interactive API reference, narrative guides, and code samples in every SDK language. Stays in sync with your OpenAPI spec automatically. Self-host or deploy to APIMatic-managed hosting.
Drop-in context for Claude Code, Cursor, and other agentic coding tools so AI agents using your API generate correct, idiomatic code on the first try.
Generate Model Context Protocol servers from the same OpenAPI spec. Token-efficient, ready for Claude, Cursor, ChatGPT, and other agent clients.
A scriptable command-line interface for your API, generated alongside your SDKs. Same spec, same custom-code model.
The same source of truth drives SDKs, docs, agent context, MCP, and CLI — so the surface stays coherent without per-language drift.
// track record
APIMatic has been generating SDKs since 2015. Our platform has processed more than a million OpenAPI specifications for teams shipping production APIs to developers around the world.
"A modern developer experience site needs several essentials: clear business value within the API, a usable code sandbox/playground, and SDKs in different languages to support developers in their preferred environment. APIMatic checked a lot of those boxes for us."
Available as managed SaaS or on-premises deployment for regulated and enterprise environments.
Send us the artifacts you already have. No engineering work required on your side.
A written report from APIMatic's SDK engineering team — scope, mapping, and quote.
A dedicated engineer sets up the SDK generation pipeline alongside your team.
Regenerate, publish to your registries, and cut over before September 1.
The migration assessment is a written report, not a sample SDK generation. We recommend starting at least 4–6 weeks before September 1, 2026, to allow time for assessment, implementation, and validation.
A written report and migration plan based on your OpenAPI spec and Stainless config. Delivered by APIMatic's SDK engineering team.
Paying Stainless customers who migrate to APIMatic receive 50% off their first-year subscription on any plan.
Every customer gets a dedicated engineer who will review their configuration and help setup the SDK Generation pipeline.
Claude Code Actions can suggest changes to a single SDK reasonably well. APIMatic generates seven idiomatic SDKs from one OpenAPI spec, preserves your custom code across regenerations, and publishes packages to every major registry — at the same time, automatically. The two solve different problems. For teams running multiple production SDKs across more than one language, APIMatic typically ends up lower-cost once you account for the senior engineer hours each LLM-generated PR still requires to review, reconcile across languages, and merge.
Open-source generators are a legitimate path, especially TypeSpec for the languages it targets. They typically produce functional but less idiomatic SDKs, have more limited customization compared to a managed platform, and require you to maintain the generator integration in your build pipeline. APIMatic's value is the managed pipeline as a whole: idiomatic output, automated publishing, custom-code preservation, and a docs/MCP/CLI suite built on the same source spec — without your team owning the toolchain.
We're not going to make a promise about the future no company can honestly make. What we can show you is the past: APIMatic has been operating since 2015, has processed more than a million OpenAPI specs, and continues to be the SDK platform for enterprises like PayPal, Shell, and Verizon. We also believe in structural protection over promises — your generated SDK code is, and will always be, yours to modify, relicense, or maintain independently, and APIMatic is available as an on-premises deployment for customers who want maximum control.
Your migration assessment includes a mapping of how your existing Stainless custom code translates to APIMatic's equivalent.
TypeScript, Python, Go, Java, C#, Ruby, and PHP. If you currently generate Kotlin or Terraform with Stainless, mention it in your migration assessment request — we can discuss your options.
Yes. APIMatic is available as managed SaaS or as a fully on-premises deployment for regulated industries, enterprises with data residency requirements, or teams that want full control over their SDK generation pipeline.
As soon as you can. Stainless's hosted platform winds down on September 1, 2026. We recommend submitting your assessment request now, with implementation starting at least 4–6 weeks before September 1 to allow time for assessment, implementation, and validation.
Per Stainless's transition announcement, you retain ownership of all generated code and can continue using and modifying it indefinitely. What stops working is the Stainless platform itself — auto-regeneration, publishing automation, the docs platform's auto fetching, and the build pipeline. APIMatic replaces those capabilities without requiring you to throw away the SDK code you already have.
It's genuinely free. The assessment is a written deliverable — report, plan, and quote — not a sample SDK generation. We've kept the scope bounded so we can offer it broadly without creating long queues. Generating a production-quality sample SDK comes later as a second step, typically scoped after the assessment is delivered.
Free migration assessment. Based on your actual OpenAPI spec and Stainless config.
Free migration assessment. Written deliverable. Based on your actual OpenAPI spec and Stainless config.
