Speakeasy
Takes an OpenAPI spec and generates polished, type-safe client SDKs across multiple languages, Terraform providers, and MCP servers for AI agent integration. Handles pagination, retries, webhooks, and streaming out of the box. Increasingly positioning itself as the API platform for the agent era.
OpenAPI Generator
The most widely adopted open-source code generator forked from Swagger Codegen. Given an OpenAPI spec, generates API client SDKs, server stubs, and documentation for 50+ languages and frameworks. 26k+ GitHub stars, 600k weekly NPM downloads, and 30M Docker pulls.