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.
Redocly
Combines Redoc (25k+ GitHub stars) with a powerful CLI for linting, validating, and bundling OpenAPI specs. Supports OpenAPI 3.x, Swagger 2.0, AsyncAPI, and Arazzo. Enterprise offering adds developer portals and auto-generated code samples across teams.