Flagr is an open source Go service that delivers the right experience to the right entity and monitors the impact. It provides feature flags, experimentation (A/B testing), and dynamic configuration. It has clear swagger REST APIs for flags management and flag evaluation.

Quick demo

Try it with Docker.

# Start the docker container
docker pull checkr/flagr
docker run -it -p 18000:18000 checkr/flagr

# Open the Flagr UI
open localhost:18000

Or try it on https://try-flagr.herokuapp.com, it may take a while for a cold start.

curl --request POST \
       --url https://try-flagr.herokuapp.com/api/v1/evaluation \
       --header 'content-type: application/json' \
       --data '{
         "entityID": "127",
         "entityType": "user",
         "entityContext": {
           "state": "NY"
         "flagID": 1,
         "enableDebug": true

Flagr Evaluation Performance

Tested with vegeta. For more details, see benchmarks.

Requests      [total, rate]            56521, 2000.04
Duration      [total, attack, wait]    28.2603654s, 28.259999871s, 365.529µs
Latencies     [mean, 50, 95, 99, max]  371.632µs, 327.991µs, 614.918µs, 1.385568ms, 12.50012ms
Bytes In      [total, mean]            23250552, 411.36
Bytes Out     [total, mean]            8308587, 147.00
Success       [ratio]                  100.00%
Status Codes  [code:count]             200:56521
Error Set:

Flagr UI