Introduction

f69 is a feature-flagging system designed for teams where UI flicker or ~100 ms vendor round-trips are unacceptable. Instead of evaluating flags in a remote SaaS, f69 ships a small Rust → WASM evaluator that runs on your edge runtime against a versioned manifest synced globally.

Why edge evaluation

Most flag platforms evaluate centrally:

1. Your app calls a vendor endpoint with the user context.
2. The vendor decides true/false.
3. You unblock the render.

That works until the vendor is far away, slow, or down. f69 inverts the model: the manifest (rules, rollouts, segments) lives next to your code, and a deterministic evaluator returns the same answer everywhere - in your edge worker, in your server, or in a CLI - byte-for-byte.

The result:

• No flicker. Decisions are local; no waiting on a network call to branch UI.
• Predictable rollouts. A frozen bucket hash means a 10 % rollout picks the same 10 % on every runtime.
• Fail-closed by default. If a flag is malformed, evaluation falls back to its declared default; one bad flag can’t break the rest.

What is in this product

You interact with f69 through two surfaces:

• Dashboard. A web UI where humans author flags, manage environments, and mint service-account tokens. Everything that changes the state of a workspace happens here.
• Edge API. The runtime surface your app calls every request - POST /v1/identify and POST /v1/evaluate, both authenticated with a service-account bearer token scoped to a single environment.

Under the hood, the same Rust evaluator that powers the edge is also available as a library (and as WebAssembly), so SDKs can resolve flags fully offline and produce byte-for-byte identical results.

Where to go next

• Quickstart - sign up, create a workspace, ship your first flag.
• Core concepts - workspaces, environments, flags, segments, MTEs, evaluations.
• Edge evaluation - how the evaluator and manifest fit together, including the rollout bucket contract.
• SDKs & API - how to authenticate and call the edge API.
• Self-hosting - run f69 in your own infrastructure.