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."
What I built
CheckAPI (https://checkapi.io) — API health monitoring with a focus on what actually matters to developers.
Key features
1. Response body keyword validation
Set a keyword that must be present (or absent) in the response body.
Example: check that "status":"ok" exists in the response — not just that the server responded.
2. SSL certificate expiry alerts
Get notified 14 days before your cert expires. Especially useful if you're using Let's Encrypt's 90-day certificates.
3. 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
4. Paid plans from $5/mo
Starter ($5): 20 monitors, 1-minute checks, 30-day history
Pro ($15): 100 monitors, 30-second checks, team sharing
Business ($49): 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
Current status
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.
👉 https://checkapi.io — free forever tier, no credit card required
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