Alert Rules
Alert rules let you watch individual Lighthouse categories — not just the rolled-up Health score — and get an email when a scan violates your thresholds.
Where to set them
On the site detail page, open Automation → Alert Rules. You can add up to 10 rules per site.
Anatomy of a rule
Each rule is three fields:
| Field | Options |
|---|---|
| Metric | Performance, SEO, Accessibility, Best Practices |
| Operator | Below, Above |
| Value | 0-100 |
Examples:
Performance Below 80— alert when performance drops under 80.Accessibility Below 95— our hard floor, never let this slip.SEO Above 99— catch weird cases where Lighthouse starts over-reporting SEO post-deploy (yes, that happens).
When rules fire
After any scan completes — manual, scheduled, or webhook-triggered — Site Health evaluates every rule against the scan's aggregate site score. If any rule is violated, one email goes out listing every violation with before/after context.
Email goes to your account email. No Slack or Discord yet.
Alert rules vs. the single Alert Threshold
The site's Alert Threshold (also in Automation) is a simpler one-field setting:
| Setting | Watches | Use when |
|---|---|---|
| Alert Threshold | Overall Health score only | You want one email when the site generally gets worse. |
| Alert Rules | Individual categories | You have category-specific SLAs — e.g., Accessibility must stay ≥ 95 even if Performance dips. |
You can have both enabled. They don't conflict; Alert Threshold watches Health, Alert Rules watch the four underlying categories.
Alert rules vs. regression detection
| Feature | Watches | Fires when |
|---|---|---|
| Alert Rules | Absolute thresholds | Current scan violates your rule. |
| Regression Detection | Deltas between scans | Score dropped meaningfully since the last scan. |
They're complementary. Regression catches change, rules catch absolute state.
Five noisy alerts a week gets ignored. Start with two rules: Performance Below 80 and Accessibility Below 95. Add more only if you miss something.
CI/CD integration
Alert rules are also evaluated by the budget-check API endpoint, so the same rules you use to get emails can fail a GitHub Actions build. One source of truth.