Performance intelligence
The Site Is Up — But the Fonts Aren't Loading. SiteWatch Tells You Why.
Your client's site loads fonts from Google, analytics from Segment, images from a CDN. When any of them go down, the site still returns 200 OK — but fonts vanish, analytics stop tracking, images break. SiteWatch monitors each third-party domain separately and fires one incident per outage, naming the failing domain and counting the affected assets. No more diagnosing third-party failures from a client phone call.
- Every third-party domain inventoried and monitored automatically
- Incident fires once per outage — auto-resolves on recovery
- Domain-level outage detection — fires when ALL assets from a vendor fail, not individual 404s
Third-party domain outage
Domain confirmed down
Affected assets
Recent activity
- THIRD_PARTY_DOWN: fonts.googleapis.com — 4 assets affected11:30 AM
- fonts.gstatic.com — 2 font files returning 50311:30 AM
- cdn.segment.com — all assets healthy11:30 AM
- Your origin — all assets healthy11:30 AM
Why it matters
Third-party failures are the most confusing incidents agencies face.
The hardest incident to diagnose
When a third-party fails, the site returns 200 OK. Uptime monitors see nothing wrong. But fonts are missing, analytics aren't tracking, or the checkout form broke. Without dependency-level monitoring, the agency finds out when the client calls.
Root cause immediately
Instead of manually opening browser DevTools on the client site, SiteWatch tells you exactly which third-party domain is failing and how many of its assets are affected. One incident card. Complete information.
Live dependency inventory
The site detail page shows a live inventory of every third-party domain a site depends on — with asset counts and health status. Agencies get portfolio-wide dependency visibility without building it themselves.
One incident per outage
SiteWatch fires the incident once when the outage begins, not on every check. No alert storms. When the third-party recovers and all assets return to healthy, the incident resolves automatically.
Uptime tools miss this entirely
Traditional uptime monitors check whether your site responds. They don't know that half your page depends on external domains. A CDN outage, a font provider going down, an analytics service failing — all invisible to ping-based monitoring.
Included across your whole portfolio
Third-party dependency monitoring runs on every monitored site on every check cycle. No extra configuration, no per-site setup. Every client site gets dependency health tracking automatically.
Per domain
Incident granularity
Auto-resolves
On dependency recovery
Every check
Monitoring frequency
Under the hood
How third-party dependency monitoring works
Classify every asset by origin
SiteWatch fetches your page and parses the HTML to extract every asset. Each asset URL is classified as first-party (your origin) or third-party (an external domain). Third-party domains are tracked separately.
Monitor per third-party domain
For each third-party domain, SiteWatch checks all its assets via HEAD requests. If ALL assets from a previously-healthy domain start failing — not just some — it indicates an outage rather than an asset-specific problem.
Fire one incident per outage
When a full-domain outage is detected, a THIRD_PARTY_DOWN incident is created at medium severity. The incident names the domain and lists how many assets are affected. It fires once — no repeated alerts while the outage continues.
Auto-resolve on recovery
SiteWatch monitors the failing domain on subsequent checks. When assets from the domain start returning healthy responses again, the incident resolves automatically and the timeline records the restoration time.
Know which vendor is down before your client does.
Free plan. No credit card. 2-minute setup.
The dependency gap
What monitoring tools see — and what they miss
| Feature | Uptime monitors | SiteWatch |
|---|---|---|
| Detects third-party CDN outage | No — site still returns 200 | Yes — THIRD_PARTY_DOWN incident |
| Names the failing domain | No visibility | Yes — domain named in incident |
| Counts affected assets | No visibility | Yes — asset count in incident |
| Dependency inventory per site | Not available | Live inventory on site detail page |
| Alert frequency during outage | N/A | Once — no alert storm |
| Auto-resolution on recovery | N/A | Yes — automatic |
Detects third-party CDN outage
Names the failing domain
Counts affected assets
Dependency inventory per site
Alert frequency during outage
Auto-resolution on recovery
FAQ
Frequently asked questions
Any asset loaded by the page from a domain different from your site's origin. This includes CDN domains, font providers (Google Fonts, Adobe Fonts), analytics services (Google Analytics, Segment), payment scripts (Stripe), chat widgets (Intercom), and any other external asset host.
Only when ALL assets from a previously-healthy third-party domain start failing simultaneously. A single asset returning a 404 fires an ASSET_MISSING incident, not THIRD_PARTY_DOWN. The full-domain condition ensures the incident represents a genuine vendor outage, not an individual asset problem.
Third-party script monitoring (the existing feature) detects individual scripts failing — a payment script returning 503, a chat widget serving the wrong MIME type. Third-party dependency monitoring operates at the domain level — detecting when an entire vendor domain goes offline, affecting all assets it serves. Both run simultaneously.
Yes. Third-party dependency monitoring covers all asset types — scripts, stylesheets, images, fonts, and other resources from external domains. The domain-level classification applies regardless of asset type.
No. A THIRD_PARTY_DOWN incident requires a full-domain outage (every asset from the domain failing) AND survives 2-of-3 retry confirmation. A brief blip on one server does not fire. Only sustained outages affecting the whole vendor domain create an incident — and only one incident per outage, regardless of duration. When the vendor recovers, the incident auto-resolves.
Yes. Third-party dependency monitoring is included on all plans — Free, Starter, and Pro. No configuration required.
Explore more
Related monitoring capabilities
Performance Baseline Regression
Detect when a site gets slower than its own normal — deployment regressions that absolute thresholds miss.
Page Weight Monitoring
Track total page download size on every check — catch bloat before it becomes a client complaint.
Third-Party Script Monitoring
Detect when individual third-party scripts fail, return wrong MIME types, or go missing.
For Agencies
Monitor dependency health across every client site from a single dashboard.