Flags docs
Guides
Build with Flags.
Twelve guides, each one self-contained. Start with getting started if you have not created a flag yet.
Every code sample on these pages is compiled against the published @productcraft/flags packages before the docs ship. Looking for one endpoint? See the API reference.
Guides
The guides
01 · Percentage rollouts
Staff first, then 10%, 50%, everyone: sticky buckets, the split attribute, and what anonymous users get.
Read more 02 · Segments
One "Beta testers" list reused across flags, hashed emails, adding a tester without retyping the list.
Read more 03 · OpenFeature
The ProductCraftFlagsProvider for the OpenFeature server SDK: context mapping, reasons, events, tests.
Read more 04 · Webhooks
config.published and sdk_key.rotated: filter by environment, verify the signature, read what changed.
Read more 05 · Testing with overrides
Local values, a JSON file or an environment variable; createTestClient in unit tests; test evaluation against the live config.
Read more 06 · Config JSON and evaluation
The config JSON (schema 1), the evaluation spec and the test vectors, for authors of SDKs in other languages.
Read more 07 · Fail-safe and caching
What your app evaluates when Flags is slow or down: the held config, your cache, the bootstrap, your defaults.
Read more 08 · Migrating from ConfigCat
Concept and SDK maps, the importer, sticky buckets, hashed values, a dual-run check and the cutover checklist.
Read more 09 · React and Next.js
FlagsProvider and useFlag, server rendering from a bootstrap without a flash, and which key may ship to a browser.
Read more 10 · Serverless and edge
Lazy polling with a shared cache for functions, and the engine on its own at the edge.
Read more 11 · Kill-switch runbook
Turn a feature off for everyone during an incident, know when every app has it, and restore the targeting after.
Read more 12 · Flag cleanup
Temporary vs permanent flags, finding the ones that are done, removing them from code and then from Flags.
Read more Packages
Which package do I need?
@productcraft/flags: theFlagsClientthat downloads and evaluates configs (Node, browsers, serverless), and theFlagsmanagement client for scripts.@productcraft/flags-react:FlagsProvideranduseFlagfor React and Next.js.@productcraft/flags-openfeature: a provider for the OpenFeature server SDK.@productcraft/flags-engine: the evaluation engine on its own, with no network code, for edge runtimes and for authors of SDKs in other languages.