David J. Phillips @davj / 2:30 PM PST • February 10, 2023

Fern launched on Y Combinator’s “Launch YC” today 🚀

Launch YC: Fern - Build APIs twice as fast ⚡

Fern is an open source format for defining REST APIs, it generates useful artifacts for your API, like SDKs, docs, and server code. It's automation for your API. Define your API once and click generate.

The company is founded by Danny Sheridan, Deep Singhvi, and Zach Kirsch. The team consists of former Palantir and AWS engineers.


Fern productizes schema-first API design. You define the schema of your API (or give them OpenAPI spec) and Fern generates:

  • SDKs in popular programming languages. Fern 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.

Image Credits: Fern

The Fern team has spent a lot of time doing repetitive, tedious tasks when writing APIs. They would write the types and networking on the backend and then do it all again in TypeScript on the frontend. They’d do it again when writing client libraries and a fourth time when updating their documentation and Postman collection.

Image Credits: Fern

Writing the same code repeatedly and keeping it all in sync is time-consuming, error-prone, and work no engineering team wants to do.

Fern lets engineering teams build APIs twice as fast. Define your API and generate server code, SDKs, documentation, and a Postman collection.


Visit www.buildwithfern.com to book a demo. Be sure to⭐️ them on GitHub! Check out their blog about how Candid Health uses Fern.

Check out the user reviews!
Image Credits: Fern

February 10, 2023
← Back to all posts  

Join Our Newsletter and Get the Latest
Posts to Your Inbox

No spam ever. Read our Privacy Policy
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.