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.
Fern
Takes an OpenAPI spec and generates hand-crafted-quality SDKs across TypeScript, Python, Go, Java, Ruby, C#, and PHP, plus integrated documentation sites. SDKs and docs stay in sync from a single source of truth. Used by Cohere, ElevenLabs, and Merge.