Fern

Emerging

Automatic multi-language SDK and API documentation generator from OpenAPI specs; $13M Bessemer-led Series A from YC W23 serving Cohere and ElevenLabs competing with Stainless for API developer experience.

Company Overview

About Fern

Fern is a New York-based API tooling company that automatically generates multi-language SDKs and API documentation from OpenAPI specifications — enabling API companies to publish high-quality client libraries in TypeScript, Python, Java, Go, Ruby, and C# from a single source of truth, eliminating the significant engineering effort of manually building and maintaining SDKs for each programming language a developer audience uses. Founded in 2022 by Danny Sheridan and Deep Singhvi and a Y Combinator Winter 2023 graduate, Fern raised $13 million total including a $9 million Series A led by Bessemer Venture Partners with 30 employees.

Business Model & Competitive Advantage

Fern's SDK generation goes beyond simple code scaffolding: the generated SDKs include idiomatic code patterns for each language (not just translated code that feels foreign to native language speakers), proper error handling, type definitions, authentication patterns, and pagination handling that matches what a senior developer would write by hand. The documentation generation produces reference docs, API playground interfaces, and code examples that match the SDK code, creating a consistent developer experience from first API call through production integration.

Competitive Landscape 2025–2026

In 2025, Fern competes in the API developer experience and SDK generation market with Stainless (SDK generation, raised $25M), Speakeasy (SDK generation), and Postman (API documentation and testing) for API developer tooling. Companies building developer-first products (APIs and developer platforms) invest heavily in SDK quality because poor SDKs directly reduce developer adoption rates — friction in the first integration experience disproportionately affects API product success. Fern's Bessemer Series A validates the commercial opportunity in API tooling infrastructure. Customers include Cohere (AI API), ElevenLabs (voice AI API), and other developer-platform companies where SDK quality directly affects revenue. The 2025 strategy focuses on growing the API company customer base, deepening the SDK generation quality for emerging programming languages, and building the API change management features that help teams handle breaking changes gracefully.

Revenue
$13M
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Key Differentiators

Emerging Innovator

Fern is an emerging player bringing innovative solutions to the Infrastructure market.

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