Problem

Fern solves the expensive, fragmented work of making a public API usable by developers. API companies must keep documentation, code examples, and client SDKs accurate across many programming languages as the API changes. When these assets are maintained manually, engineering teams spend substantial time on repetitive implementation and support: one customer reported that keeping docs, SDKs, and its server implementation in sync was “a nightmare,” while another saved more than 7,000 engineering hours per year by generating seven SDKs from one specification.

The killer use case is accelerating adoption of a customer-facing API. High-quality, idiomatic SDKs let developers call the API from their preferred language, while accurate interactive documentation reduces onboarding friction and support demand. Fern cites a 99% reduction in time to a first successful API call—from one to fourteen days to under an hour—and more than 1,500 hours of annual support time saved in a customer case study.

Product / Service

Fern is a developer-experience platform that turns an API definition into synchronized documentation, production-ready SDKs, and an agent-first CLI. Teams can generate TypeScript, Python, Go, Java, C#, PHP, Ruby, Swift, and Rust SDKs from a single specification, run generation in CI, and automatically publish updated packages and API reference documentation. It supports formats and protocols including OpenAPI, AsyncAPI, gRPC/Protobuf, GraphQL, WebSockets, and OpenRPC.

The delivery model combines a managed cloud product with an enterprise self-hosting option. Fern hosts customizable documentation sites with search, API references, versioning, and interactive features, while its docs-as-code CLI fits into Git-based development workflows. Its newer AI-oriented capabilities include searchable agent-friendly documentation, llms.txt, an MCP server, and AI-assisted authoring. The commercial model includes a free Hobby tier, a $150-per-month Team tier, and custom-priced Enterprise plans with features such as SSO, RBAC, and self-hosting.

Market

Fern competes in API developer experience and API documentation/SDK-generation software: a category that helps companies expose APIs through polished documentation and maintainable client libraries without building an internal SDK and developer-portal stack. Its named competitors include Speakeasy, Stainless, APIMatic, ReadMe, and the open-source OpenAPI Generator. Fern’s positioning is integration: unlike documentation-only products such as ReadMe or basic code-scaffolding tools, it generates docs and idiomatic SDKs from the same source of truth and adds hosting, publishing, analytics, and AI-oriented capabilities.

Fern is an established commercial business rather than a pre-launch company. It announced a $9 million Series A in April 2025, bringing total funding to $13 million; Postman acquired it in January 2026, with Fern’s team, product, brand, and roadmap continuing under Postman. The acquisition announcement reported more than 200 customer companies, including Square, Auth0, Adobe, Twilio, and ElevenLabs, while Fern’s current site reports 8,000-plus customers across Docs, SDKs, and CLI, 1.5 million unique documentation users per month, and more than 1 million combined SDK downloads per week. Revenue is not publicly reported in the available evidence, but the paid plans, customer base, funding, and acquisition demonstrate meaningful commercial traction.