Statsig
A weekend of work, and real gaps remain.
Feature flags and experimentation with the statistics done for you: rollouts, holdouts and results reported with confidence intervals rather than raw counts.
Build the flags. Be careful about the statistics. STACK - A JSON config file read at boot and refreshed on a signal, plus your existing events table FLAGS - A flag is a name, a default, and optional rules by user attribute - Percentage rollouts by hashing user id with the flag name, so a user stays on one side - Never use a random number: it flips on every request EXPERIMENTS, WITH A WARNING - Assignment by the same hash, recorded as an event at the moment of exposure - Do not peek. Checking daily and stopping when it looks good inflates false positives badly - Fix the sample size and the duration in advance, and write both down before starting READING RESULTS - Compute the difference and a confidence interval. If the interval crosses zero, you learned nothing Include the flag evaluator, the exposure event and the sample size calculation.
What you lose
- Sequential testing and variance reduction done properly, which is where home-made experiments go wrong
- Automatic detection of a flag that is hurting a metric
- A single SDK covering flags, experiments and metrics
If you would rather not build
- A JSON file in your repository, for a handful of flags
The escape hatch
open source · no votes, no paid placement
Unleash
$0A self-hosted feature flag service with SDKs for most languages.
Unleash/unleashfree · open source
Flagsmith
$0Feature flags and remote config, self-hostable with an admin interface.
Flagsmith/flagsmithfree · open source
Why this verdict
our own opinion · changed only by a person
56/100
Verdict kinda at 56. Flags are easy and the prompt gives you a correct rollout. The statistics are where a home-made version quietly misleads you.
History
tracked since 10 Aug 2026 · nothing is ever overwritten
Questions about Statsig
answered from the record above
Is Statsig free?
No — the plan we track is $0 a month. Free up to a generous monthly event allowance; billing starts above that on events and sessions.
Can you replace Statsig by building your own?
ALMOST. A weekend of work, and real gaps remain. Replacement score 56 out of 100, build time a weekend. Read what you lose before you decide.
How much does Statsig cost?
$0 a month on Free tier — $0 a year. Recorded 10 Aug 2026.
What do you lose by replacing Statsig?
Sequential testing and variance reduction done properly, which is where home-made experiments go wrong; Automatic detection of a flag that is hurting a metric; A single SDK covering flags, experiments and metrics. If any of those carry weight for you, keep paying.
Is there an open-source alternative to Statsig?
Yes: Unleash, Flagsmith. The prompt on this page is for when you want it your way instead.
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