OpenFeature SDK

Evaluate Flagship feature flags using OpenFeature.

OpenFeature ↗ is the CNCF standard for feature flag interfaces. It provides a vendor-neutral API so you can switch between flag providers without changing evaluation code.

Flagship provides official OpenFeature-compatible SDKs for TypeScript, Python, and Go. The source code is available on GitHub ↗.

SDK	Package	Runtime	Evaluation modes
TypeScript	@cloudflare/flagship ↗	Workers, Node.js, browsers	Workers binding, HTTP, browser prefetch cache
Python	cloudflare-flagship ↗	Python server applications	HTTP
Go	github.com/cloudflare/flagship/sdks/go ↗	Go server applications	HTTP

SDKs

Flagship SDKs are organized by language. The TypeScript SDK has separate setup guides for server-side and browser usage because they use different OpenFeature packages and runtime behavior.

• TypeScript Server SDK — For Workers, Node.js, and other server-side JavaScript runtimes.
• TypeScript Client SDK — For browser applications that need synchronous OpenFeature web SDK evaluation.
• Python SDK — For Python server applications.
• Go SDK — For Go server applications.

Note

If you are running inside a Cloudflare Worker, the binding is the recommended approach because it avoids HTTP overhead. You can also pass the binding to the OpenFeature SDK to get the best of both. Use the SDK without a binding when running in non-Worker runtimes like Node.js or the browser.

Installation

For TypeScript server-side usage:

npm yarn pnpm bun

npm i @cloudflare/flagship @openfeature/server-sdk

yarn add @cloudflare/flagship @openfeature/server-sdk

pnpm add @cloudflare/flagship @openfeature/server-sdk

bun add @cloudflare/flagship @openfeature/server-sdk

For TypeScript browser usage:

npm yarn pnpm bun

npm i @cloudflare/flagship @openfeature/web-sdk

yarn add @cloudflare/flagship @openfeature/web-sdk

pnpm add @cloudflare/flagship @openfeature/web-sdk

bun add @cloudflare/flagship @openfeature/web-sdk

For Python:

uv add cloudflare-flagship

For Go:

go get github.com/cloudflare/flagship/sdks/go

Next steps

• Set up the server provider for Workers, Node.js, or other server-side runtimes.
• Set up the client provider for browser applications.
• Set up the Python SDK for Python server applications.
• Set up the Go SDK for Go server applications.