Stoplight
Design-first platform for creating, governing, and documenting OpenAPI specifications. Bundles a visual editor, Spectral (JSON/YAML linter), Prism (mock server), and Elements (docs renderer) into one workflow. Teams use it to enforce API style guides across large API portfolios.
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.