Eppo proves significance.
Xi proves the verdict.
Eppo is the modern experimentation platform built for product teams that take statistics seriously: warehouse-native, sequential testing, CUPED variance reduction, per-experiment power analysis. Xi makes a different bet — that for most marketing experiments, a kill threshold set up front beats chasing p-values on small N.
Why teams switch from Eppo to Xi
Eppo is excellent at statistical rigor — and that is exactly what marketing experiments often do not need. A pricing change, an outbound test, a content cadence — these run on small N where chasing significance is the wrong frame. Xi makes the contract the decision rule: write what you would kill, what you would ship, when you would decide. The math does not have to do the work.
- Contract over significance. Pre-commit a threshold; the rules decide. Sequential testing, CUPED, and confidence intervals are valuable on product traffic — not on a 4-week paid test with a few hundred conversions.
- No data warehouse required. Eppo plugs into Snowflake, BigQuery, or Redshift and metrics live there. Xi works with the metric you already track, however you track it.
- A free plan that does not expire. Unlimited experiments, unlimited archive, no card. Eppo is sales-led with no public free tier.
- The agent runs it. MCP-native, so Claude can commit, log, and decide experiments. Eppo has APIs but no native MCP today.
If you have product traffic and a data team, Eppo is the right call. If you have marketing experiments and small N, switch.
Where the two tools actually differ.
When each tool is the right call.
- You have a data team and a warehouse with clean event data.
- You run high-traffic product experiments where statistical rigor is the unblock.
- You need sequential testing, variance reduction, and per-experiment power analysis.
- Your experiments are tied to features deployed in the codebase.
- Your experiments run on small N where chasing significance is the wrong frame.
- You do not have a data warehouse, or your metrics live outside it.
- You want a contract per experiment and a verdict at the end.
- You want the agent to commit and decide experiments via MCP.
Common questions, short answers.
How is Xi different from warehouse-native experimentation tools?
Different unit of work and different decision rule. Warehouse-native tools optimize statistical analysis on product traffic. Xi captures contracts that decide marketing experiments by pre-committed thresholds, regardless of N.
Can I use Xi alongside Eppo?
Yes. Use Eppo for warehouse-native product experiments where statistical rigor is the unblock. Use Xi for marketing experiments and the cross-channel contract archive.
Does Xi do CUPED or sequential testing?
No, intentionally. Marketing experiments rarely have the N or homogeneity for variance reduction to help. The contract is the discipline: pre-commit a threshold, let the rules decide.
Do I need a data warehouse?
No. Xi works with whatever metric source you already trust.
Take one idea. Turn it into an experiment.
Free plan, unlimited archive, no card required. See it in Claude / Cursor / Codex in 30 seconds.