Stainless

Stainless generates client SDKs for an API from its OpenAPI spec. The libraries come out looking hand-written, with typed models, retries, pagination helpers and good error handling. Several well-known AI companies use it for their official SDKs.

You give it your spec and some configuration, and it produces packages for languages like TypeScript, Python, Go and Java that stay in sync as your API changes. That saves teams the ongoing work of maintaining many SDKs by hand.

It is a commercial product aimed at companies with a public API. A small side project will not need it, but anyone shipping a developer platform should look closely.