Flagr

Judgement

What it is

Complete system

What it does

A Go microservice for feature flags, A/B tests and dynamic configuration that returns a variant per entity through an evaluation API, with a web UI.

Adopt it when

You want a lightweight, self-hosted flag and experiment service called over HTTP from any language.

Watch out

A small community-maintained fork after Checkr stepped back.

Ready for

Usable

Runs as

Self-hosted server

Built with

Go, Vue and PostgreSQL

How established

Established: started 9 years ago, latest release 1.2.4.

What the license allows

You can build it into a product you sell, as long as you keep its copyright notice.

Judged on 2026-11-03 from the project's README and GitHub data. The license and age lines are worked out directly.

Compare Flagr

Built from

Follow it down: Flagr → Go → runs on a microchip

How compilers were built, back to punched paper tape

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