CheckAPI was born from a simple frustration — existing monitoring tools either missed the real failures or cost too much for what they offered.
Sewon Jeon
Founder · Seoul, South Korea 🇰🇷
I was running APIs in production and kept getting surprised by failures my monitoring tool completely missed. The API returned 200 OK — but the response body was broken. Null data. Silent errors buried in JSON. My monitor said everything was fine. My users knew otherwise.
I wanted a tool that validated the actual response body — with regex patterns and JSON path assertions — not just the status code. Something that catches silent failures before users do.
The existing options were either too expensive, too limited, or locked real features behind paid tiers. So I built CheckAPI: the monitoring tool I actually wanted to use.
CheckAPI is a one-person product, built and maintained by me from Seoul. Every feature request gets read. Every bug gets fixed. No bloat, no committees — just a developer building the tool that works.
Most monitors stop at HTTP 200. CheckAPI goes deeper — validating response bodies with regex and JSON path assertions to catch silent failures.
Free means free. No commercial-use restrictions, no credit card required, no 1-monitor limits. 5 monitors, all alert channels, actual production use — on the free plan.
Not a VC-backed startup optimizing for growth metrics. A developer building the tool they actually wanted to use. Simpler, faster, more honest.