What is the top free pick among Flags?

Unleash leads the Stack Gems list for Flags. Verdict: AGPLv3 flags. Self-host with OSS caps; Cloud trial is not free forever.

How many Flags does Stack Gems review?

4: 2 free or open source, 2 hosted with a real free tier. Each review has a verdict and an honest Catch; no tool pays for its spot.

Which Flags have the most GitHub stars?

PostHog (40.4k), Unleash (13.9k), GrowthBook (8.5k), per GitHub on 2026-10-21. Stars measure attention, not fit; read the Catch.

What is the catch with Unleash?

OSS caps Projects 1 / Environments 2.

Tag

Flags

4 reviewed tools: 2 free or open source, 2 hosted with a real free tier.

Order: free and open source first, then hosted products with a real free tier, then paid-led; catalog order inside each group, with quiet or archived repos last. Not a score, and no tool pays for its place.

4 tools

UnleashAGPLv3 feature flags; OSS caps 1 project / 2 environments
Free / OSS · AGPL-3.0 · 13.9k GitHub stars
VerdictAGPLv3 flags. Self-host with OSS caps; Cloud trial is not free forever.
CatchOSS caps Projects 1 / Environments 2. Cloud = Enterprise trial FAIL — pitch self-host only. Vs PostHog dedicated-flags-inside-analytics. Distinct from PostHog.
FlagsmithBSD-3-Clause flags; Cloud Free 50k req/mo, self-host uncapped
Free / OSS · Freemium · 6.6k GitHub stars
VerdictBSD-3 flags. Cloud Free is real but capped; self-host for scale.
CatchCloud Free is capped (50k/1 seat/1 project); self-host uncapped. Vs PostHog analytics-native flags and Unleash AGPL OSS caps. Distinct from PostHog and Unleash.
PostHogProduct analytics, flags, replay, and errors in one MIT-core stack
Free tier · Freemium · 40.4k GitHub stars
VerdictThe honest Mixpanel/Amplitude alternative. MIT core, real free Cloud, ee/ is not MIT.
Catchee/ is a separate proprietary license. posthog-foss strips it if you need a clean MIT tree. Self-hosting is a Postgres + ClickHouse ops job. Cloud is usage-metered after the free allowances; replay is usually the line that bites first.
GrowthBookMIT-core flags+experiments; Cloud Starter Free, self-host unlimited users
Free tier · Freemium · 8.5k GitHub stars
VerdictMIT-core flags+experiments. Cloud Starter Free is real; ignore Pro seats.
CatchWarehouse-native experimentation competitor to PostHog — different pitch (flags+experiments first). Cloud Starter Free has user/project caps; self-host OSS uncapped users. Distinct from PostHog.

FAQ

What is the top free pick among Flags?: Unleash leads the Stack Gems list for Flags. Verdict: AGPLv3 flags. Self-host with OSS caps; Cloud trial is not free forever.
How many Flags does Stack Gems review?: 4: 2 free or open source, 2 hosted with a real free tier. Each review has a verdict and an honest Catch; no tool pays for its spot.
Which Flags can I self-host for free?: Unleash and Flagsmith.
Which Flags have the most GitHub stars?: PostHog (40.4k), Unleash (13.9k), GrowthBook (8.5k), per GitHub on 2026-10-21. Stars measure attention, not fit; read the Catch.
What is the catch with Unleash?: OSS caps Projects 1 / Environments 2.