Haystack

Replay real customer journeys against every change before you ship

·Developer Tools·YC Summer 2024·tracked since Sep 25, 2026
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Monthly revenue–Not shared yet
Rank–Unranked
Last 30 days–Growth in MRR
Revenue per founder–– founders

About Haystack

Haystack automatically learns real customer journeys from production traffic, figures out which ones a code change could affect, and replays them in isolated copies of production to catch regressions before they ship. When something breaks, Haystack shows exactly what changed across the UI, network calls, and events, then gives the failure back to your coding agent to fix and rerun. Teams get high-fidelity QA without having to write or maintain test cases.

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