togglefleet

https://github.com/takeaseatventure/togglefleet-ruby

ToggleFleet is a hosted feature-flag service for Ruby. This gem fetches your environment's flags once, refreshes them in the background with conditional ETag requests, and evaluates all five gates — boolean, actor, group, percentage-of-actors (sticky), and percentage-of-time — entirely in-process. Checking a flag is a hash lookup, not a network call, so flags cost nothing on the hot path and keep working at their last known values if ToggleFleet is unreachable. Zero runtime dependencies — only the Ruby standard library. Thread-safe, fork-safe under Puma/Unicorn/Passenger, and fail-safe by design: any error returns your configured default rather than raising into a request. Evaluation is byte-identical to server-side evaluation, including MD5 bucketing, so a sticky rollout targets exactly the same actors whether it is resolved locally or through the API. Group membership is decided by predicates in your own code, so no user data leaves your process. Requires a ToggleFleet account for an SDK key. Full documentation at https://togglefleet.com/docs.