I built an API monitoring tool because every existing one either costs too much or restricts commercial use

Source: Dev.to

The problem

I was building a side project and needed to monitor a few API endpoints. I tried the usual suspects:

• UptimeRobot (free) – 50 monitors, sounds great — until you read “non‑commercial use only”.
• Better Uptime – $20 /mo minimum for anything useful.
• Pingdom – No free tier at all.
• Datadog – Powerful, but $100+/mo overkill.

All of them also share another problem: they only check status codes. Your API can return 200 OK with a body of {"error": "database connection failed"} and most uptime tools will happily mark it as “up”.

CheckAPI

CheckAPI – API health monitoring with a focus on what actually matters to developers.

Features

• Response body keyword validation – e.g., "status":"ok" exists in the response, not just that the server responded.
• SSL certificate expiry alerts.
• Free tier with no commercial restrictions
  • 10 monitors
  • 5‑minute check intervals
  • All 5 alert channels (Email, Slack, Telegram, Discord, Webhook)
  • No “non‑commercial use only” restriction
• Paid plans
  • Pro ($15/mo): 100 monitors, 30‑second checks, team sharing
  • Business ($49/mo): Unlimited monitors, 10‑second checks, 1‑year history

Tech stack

• Backend: FastAPI + Celery + Redis + PostgreSQL (Railway)
• Frontend: Next.js 14 + TypeScript + Tailwind CSS (Vercel)
• Alerts: Resend (email), direct API calls for Slack/Telegram/Discord/Webhook

Call for feedback

Just launched. $0 MRR. Building in public at @imwon_dev.
Would love feedback — especially if you’ve hit the “non‑commercial use” wall with other tools, or if keyword validation would have caught a bug for you.

👉 — free forever tier, no credit card required.