Open-source feature flags, A/B testing, and dynamic configuration.

Flagr is a Go service for feature flags, A/B tests, and dynamic configuration. You call POST /api/v1/evaluation, Flagr looks at who is asking, and returns a variant with an optional JSON attachment. One primitive, the flag, powers it all.

Use it to ship code dark and turn it on per audience, run experiments with sticky assignment, or change runtime config without redeploying.

openflagr/flagr continues development from the original checkr/flagr.

docker pull ghcr.io/openflagr/flagr
docker run -it -p 18000:18000 ghcr.io/openflagr/flagr

open http://localhost:18000

Try it live: try-flagr.onrender.com (may cold-start)

curl -sS -X POST https://try-flagr.onrender.com/api/v1/evaluation \
  -H 'content-type: application/json' \
  -d '{
    "entityID": "127",
    "entityType": "user",
    "entityContext": { "state": "NY" },
    "flagID": 1,
    "enableDebug": true
  }'

We love contributions. Open an issue or send a pull request.

Have an idea for a new project or feature? Open an issue here at the org level and let's talk.