OpenFeature SDKs

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 and Python. The source code is available on GitHub ↗.

For Cloudflare Workers, use the Workers binding when possible. Use an SDK when you need OpenFeature compatibility, are running outside Workers, or need browser-side flag evaluation.

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

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.

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.

TypeScript installation

For 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 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

Python installation

Install the Python SDK with uv or pip:

uv add cloudflare-flagship

pip install cloudflare-flagship

The Python SDK provides FlagshipServerProvider for server-side applications. It supports HTTP evaluation, sync and async APIs, all OpenFeature flag types, retries, timeouts, and optional response caching.

Next steps

• Set up the TypeScript Server SDK for Workers, Node.js, or other server-side runtimes.
• Set up the TypeScript Client SDK for browser applications.
• Set up the Python SDK for Python server applications.