github.com/openflagr/flagr @1.2.2 sqlite

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What is Flagr?

Flagr is an open-source Go service for feature flags, A/B testing, and dynamic configuration. One primitive — the flag — covers all three: a decision point in your code that the evaluation engine resolves at runtime based on who is asking.

It exists to decouple deploy from release — turn a feature on for one user, a thousand, or nobody, without redeploying. Run experiments and trust the numbers. Change configuration without a code change or a restart.

openflagr/flagr is the community-driven home of Flagr, advancing development beyond the original checkr/flagr.

📖 Documentation

https://openflagr.github.io/flagr

Developers: clone the repo and run make help for build, test, and UI commands (single entrypoint for CI and local work).

Features

• Feature flags — binary on/off, kill switches, targeted rollouts by audience
• Duplicate flag — clone variants, segments, constraints, distributions, and tags to a new flag (POST /flags/{id}/duplicate or Flag Management on flag detail)
• A/B testing — multi-variant experiments with deterministic, sticky assignment
• Dynamic configuration — per-variant JSON attachments, no redeploy or restart
• GitOps / Flags-as-code — load flags from JSON or HTTP; manage in Git, validate in CI, rollback with git revert
• Exposure logging — POST /exposures for client-reported impressions, the trustworthy A/B denominator
• Webhook notifications — HTTP POST on every flag change, with retry and backoff
• Multi-database — SQLite (dev), MySQL, PostgreSQL, and JSON sources
• Vue 3 UI — TypeScript management UI (Vite, typed REST via ApiResult); see make help for build-ui / test-e2e

Quick start

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

# Open the Flagr UI
open localhost:18000

Or try the hosted demo at https://try-flagr.onrender.com (cold starts may take a moment):

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

Flagr UI

<img src="https://github.com/openflagr/flagr/raw/1.2.2/docs/images/demo_readme.png" width="900">

Architecture

Flagr has three components:

• Evaluator — serves evaluation from an in-memory cache of all flags. The cache refreshes periodically (default 3s) and short-circuits when nothing changed, so evaluation never touches the database on the request path.
• Manager — the CRUD gateway; all flag mutations flow through here.
• Metrics — fans evaluation and exposure events out to your data pipeline (Kafka, Kinesis, Pub/Sub) or the built-in Datar aggregates. Recording is asynchronous, so a slow backend never stalls an evaluation.

See the architecture overview for diagrams, request flows, and the deterministic bucketing algorithm.

Performance

Tested with vegeta — 2,000 req/s sustained, sub-millisecond median latency:

Requests      [total, rate]            56521, 2000.04
Duration      [total, attack, wait]    28.26s, 28.26s, 365.53µs
Latencies     [mean, 50, 95, 99, max]  371.63µs, 327.99µs, 614.92µs, 1.39ms, 12.50ms
Success       [ratio]                  100.00%
Status Codes  [code:count]             200:56521

Client Libraries

License and Credit

• openflagr/flagr — Apache 2.0
• checkr/flagr — Apache 2.0 (original project)