Free A/B test statistical significance calculator with frequentist, Bayesian, and multi-variant comparison.
ABWex is a free A/B test calculator that provides both frequentist Z-test and Bayesian Beta-Binomial analysis. Compare up to 4 variants simultaneously, project revenue impact, and plan sample sizes — all running entirely in your browser with no data sent to any server. Built for growth marketers, product managers, and data analysts running rigorous experiments.
- Frequentist Z-test with p-value, Z-score, and 95% confidence intervals
- Bayesian Beta-Binomial analysis with P(B beats A) and expected loss
- Multi-variant comparison for up to 4 variants (A/B/C/D)
- Revenue impact projections from conversion rate differences
- Sample size pre-calculator with statistical power curves
- Duration estimates based on traffic volume
- Formula transparency showing the exact math behind every result
- Plain-English interpretation of results for non-statisticians
- 100% client-side — no data leaves your browser
- MIT licensed
- No signup, no tracking
- Pure HTML, CSS, and vanilla JavaScript
- No build step
- No external dependencies (except Google Fonts on some pages)
- Hosted on GitHub Pages with Cloudflare CDN
ABWex is part of Zovo Tools — free developer tools by a solo developer. No tracking, no signup, no nonsense.
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MIT licensed.
Built and maintained by Michael Lip. For questions or feedback: support@zovo.one