Stripe-level SDKs and Docs for your API

REST APIs underpin the internet but are still painful to work with. They are often untyped, unstandardized, and out-of-sync across multiple sources of truth. Deliver Stripe-level SDKs and Docs to your API users. Upload your OpenAPI, or define your API in Fern's simpler format, and generate SDKs in popular programming languages. Fern handles publishing to package managers like NPM and PyPI. When you use Fern for SDKs and Docs, you get SDK code samples automatically populated in your documentation. Discover how Fern helps developer-focused companies: https://buildwithfern.com/showcase

Team Size:4
Location:New York

Active Founders

Danny Sheridan

Howdy, I'm Danny the CEO at Fern. In my last gig, I was a product manager at AWS. Prior to that, I founded an e-commerce business in high school, scaled it in college, and that experience led me to join Amazon. My journey: Cleveland --> Ann Arbor --> Seattle --> San Francisco --> New York

Danny Sheridan
Danny Sheridan

Deep Singhvi

Deep is a YAML engineer at Fern. Before Fern, he worked as a software engineer at Palantir focusing on data integration at the Department of Defense and US Army.

Deep Singhvi
Deep Singhvi

Company Launches

TLDR: Fern generates useful artifacts for your API, like SDKs, docs, and server code. Star us on GitHub! ⭐

Steve Yazicioglu, Head of Engineering at Candid Health (Series A)


When building APIs, we spent a lot of our time doing things like:

  • Writing types & networking logic on the backend
  • Communicating details of the API endpoints over Slack
  • Re-writing the same types & networking logic on the frontend
  • Re-writing the same types & networking logic in each SDK or client library
  • Re-writing the same information in our docs & Postman Collection

Inevitably, these multiple sources of truth get out of sync, causing runtime bugs, wasted hours of debugging, and frustration.


Fern productizes schema-first API design. You define the schema of your API (or give us an OpenAPI spec) and we generate:

  • SDKs in popular programming languages. Our SDKs feel handwritten. They can be used externally for customers or internally for your frontend/microservices.
  • API docs that sync to your provider of choice.
  • Postman Collection complete with examples of successful and unsuccessful requests
  • Server-side validation to make sure that you serve the API you promised.

Fern also registers all versions of your API in a registry — no need to ping a coworker over Slack to understand how to consume an API.

With love 💌,
Team Fern 🌿 (Deep, and Danny)

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YC Sign Photo

YC Sign Photo