PostHog

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Do not rebuild the suite — but notice the idea, because it is the best one in this category and it is free to copy.

**One event stream feeding every tool.** Product analytics, session replay, feature flags and experiments all reading the same events, so a funnel, a flag and a replay agree with each other by construction rather than by reconciliation. That is an architecture, and you can adopt it whatever you use.

FIRST, CHECK THE TIER
- The free allowance is large and the software is open source, so self-hosting is a real answer. Many people paying here would be fine on either
- Self-hosting it is genuinely heavier than the other open products in this catalogue — it wants a columnar store and real memory. Price that honestly against the hosted bill

WHEN TO KEEP PAYING
- You use three or four of the tools and value that they agree
- Volume where recomputing a funnel in seconds is doing real work

WHAT TO COPY, WHATEVER YOU DECIDE
- **Everything is one events table** with a name and properties. A new signal is a new name, never a migration
- Both the anonymous and the identified identifier on every row, so stitching applies retroactively rather than requiring a rewrite
- Feature flags evaluated locally from a cached rule set, with the exposure written as an event into the same stream. Then 'did the people who saw the new thing convert better' is one query rather than a reconciliation between two products
- Record more than you publish. A signal not captured today starts from zero the day somebody wants it

AND THE PART TO BE CAREFUL WITH
Session replay in the same product makes it very easy to turn on. Mask by default, never capture a password field under any configuration, set a retention in days, and log who watched whose session. Those controls matter more when replay is one switch away.

THE ONE-LINE VERSION
Check whether the free tier covers you. Then take the architecture — one event stream, both identifiers, flags writing exposures into it — regardless of what you pay for.