GrabDiff / comparisons
GrabDiff vs UptimeRobot
Last reviewed May 2026. Pricing from public sources; verify before buying.
UptimeRobot is one of the most popular uptime monitors on the market. It has a generous free tier, simple setup, and sends alerts fast. The thing it does not do is look at the page. It sends an HTTP request, checks the status code, and calls it done. If your React app crashes and renders a white screen, UptimeRobot reports "up." If your CDN starts serving a cached error page with a 200, UptimeRobot reports "up." That is the gap GrabDiff was built to fill.
Feature comparison
| Feature | GrabDiff | UptimeRobot |
|---|---|---|
| HTTP uptime checks | Yes | Yes |
| Screenshot on each check | Yes | No |
| Pixel-diff alert | Yes | No |
| Screenshot history | Yes | No |
| Catches JS crashes / blank screens | Yes | No |
| SSL expiry alerts | All plans | Paid only (Solo+) |
| Domain expiry alerts | All plans | Paid only (Solo+) |
| Cron heartbeat monitoring | All plans | Paid only (Solo+) |
| Webhook alerts | Paid plans | Team plan+ |
| Multi-location checks | No | Paid only |
| Status pages | Not yet | Yes |
| Free tier monitors | 3 monitors | 50 monitors |
| Free tier check interval | 1 min HTTP / 30 min screenshot | 5 minutes |
| Paid entry price | $9/mo (Solo, 20 monitors) | $7/mo annual (Solo, 50 monitors) |
Where UptimeRobot wins
Free tier is far more generous: 50 monitors versus GrabDiff's 3. If you need to monitor a lot of endpoints with simple HTTP checks and no visual component, UptimeRobot's free plan is hard to beat. It also has a bigger ecosystem: mobile apps, multi-location checks, status pages, and 12 integrations on paid. And it has been around since 2010, so the reliability track record is long.
Where GrabDiff wins
GrabDiff actually looks at the page. A JavaScript crash, an empty database-driven page, a CDN serving a stale error, a deploy that broke the layout: these all return 200 and UptimeRobot never notices. GrabDiff runs headless Chrome, takes a screenshot, diffs it against the last known-good state, and pages you. You can also view the screenshot history to see exactly what your page looked like at any point.
SSL expiry, domain expiry, and heartbeat monitoring are also on GrabDiff's free plan. On UptimeRobot those features require a paid Solo subscription.
Which to use
Run both if you want. They are catching different classes of failure. UptimeRobot is fast at detecting pure server-down events and has a large free tier. GrabDiff catches the "server is up but the page is broken" class. If you have more than 3 simple endpoints that only need HTTP checks, UptimeRobot's free tier is the right choice. If you have even one URL where you need to know when it looks broken, not just when it returns a non-200, GrabDiff is what you want.