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Flagr is a feature flagging, A/B testing and dynamic configuration microservice


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openflagr/flagr is a community-driven OSS effort of advancing the development of Flagr.

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
docker run -it -p 18000:18000

# Open the Flagr UI
open localhost:18000

Or try it on, it may take a while for a cold start, and every commit to the main branch will trigger a redeployment of the demo website.

curl --request POST \
     --url \
     --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

Client Libraries

Language Clients
Go goflagr
Javascript jsflagr
Python pyflagr
Ruby rbflagr

License and Credit