Your monitoring says 100% uptime.
Your customers say the checkout is broken.
Both are telling the truth.
Here are 5 real failures that slip through every traditional monitoring setup — and how to actually catch them.
1. The Invisible Button
What happened: A CDN cache update pushed a CSS change that set display: none on the checkout button. The page loaded fine. HTTP status: 200 OK.
Impact: 3 enterprise prospects visited the pricing page. All 3 bounced. Estimated loss: €75K ARR.
Why monitoring missed it: Status code monitors check if the server responds, not if the button exists in the DOM.
Fix: Monitor what users see, not what servers return.
2. The JavaScript Time Bomb
Try this right now:
- Open your production site
- Open DevTools (F12)
- Run:
throw new Error("Test crash") - Wait 5 minutes
Did your monitoring alert you?
If the answer is no, you’re blind to every JavaScript error your users encounter. That includes:
- React hydration failures
- Third-party script crashes
- Payment SDK timeouts
Most teams discover JS errors from customer support tickets — days later.
3. The Price That Became Zero
A broken API response caused every pricing plan to display $0.00. The backend returned 200 OK with valid JSON — the values were just wrong.
No alert. No notification. A customer screenshot on Twitter was the first signal.
The lesson: A 200 OK with garbage data is worse than a 500 — because nobody investigates a green dashboard.
4. The Vendor Status Page Lie
Your infrastructure vendor’s status page says “All Systems Operational” while their API latency is 10x normal.
You can’t install Datadog on their servers. You can’t add Prometheus to their infrastructure.
The only way to catch this: monitor their pages from the outside, like a real user.
5. The Form That Lost Its Submit
After a dependency update, your signup form rendered without a submit button on Safari. Chrome worked fine. Your synthetic monitor runs on Chrome.
Result: 15% of signups silently failed for 3 days.
The 3 Levels of Web Monitoring
Where does your team sit?
| Level | What You Monitor | Blind Spots |
|---|---|---|
| Level 0 | Backend API status (Prometheus, Datadog APM) | DOM, JS errors, UX |
| Level 1 | Synthetic HTTP checks (Pingdom, UptimeRobot) | HTTP 200 ≠ working page |
| Level 2 | Real user experience (DOM content, interactions) | None — you see what users see |
If you’re at Level 0 or 1, you’re missing up to 90% of real failures.
Quick ROI Math
Undetected downtime: 1h/month
Revenue per hour: €10K
Annual loss: €10K × 12 = €120K
Monitoring cost: €15/month = €180/year
ROI: 666x
It’s the cheapest insurance in your stack.
Try It in 30 Seconds
We built ArkWatch to catch exactly these failures.
- Monitors the DOM, not just status codes
- AI-powered diffs that filter noise from real changes
- 30-second alerts when something breaks
- 60-second setup — one API call
- 14-day free trial, no credit card
curl -s https://watch.arkforge.fr/api/check?url=YOUR-SITE.com
If your monitoring has never caught a DOM failure, give it a shot.
Built by ArkForge. We monitor what your users actually see.
