Atatus browser alerts monitor real user monitoring (RUM) data to detect performance issues affecting your end users. You can alert on page load times, Core Web Vitals, AJAX performance, transaction success rates, and JavaScript error counts.

Browser alerts also support baseline alerts for detecting deviations from historical patterns.

Available metrics

Page load metrics

Metric Summary Function Unit
Page Load Time - avg average seconds
Page Load Time - p90 p90 seconds
Page Load Time - p95 p95 seconds
Page Rendering Time average seconds
DOM Processing Time average seconds
Network Time average seconds
Page View Throughput throughput pageviews
Apdex Score apdex apdex

Core Web Vitals

Metric Summary Function Unit
FCP - First Contentful Paint average seconds
LCP - Largest Contentful Paint average seconds
FID - First Input Delay average seconds
CLS - Cumulative Layout Shift average —
TTFB - Time To First Byte average seconds

AJAX metrics

Metric Summary Function Unit
Ajax Total Time average seconds
Ajax Response Time average seconds
Ajax Callback Time average seconds
Ajax Throughput throughput calls
Ajax Error Count throughput count
Ajax Error Rate percent %

Transaction metrics

Metric Summary Function Unit
Transaction Time average seconds
Transaction Throughput throughput calls
Transaction Failure Throughput throughput calls
Transaction Failure Percentage percent %

JavaScript errors

Metric Summary Function Unit
JS Error Count throughput count

Enter thresholds in the unit shown. For time metrics, enter the value in seconds (e.g., 5 for 5 seconds). The alert engine handles internal unit conversion automatically.

Baseline metrics

Browser alerts also support baseline metrics that compare the current value against a historical moving average. See Baseline alerts for details.

Supported browser baseline metrics: Page Load Time, Page Rendering Time, Page View Throughput, JS Error Count, AJAX Total Time, AJAX Response Time, AJAX Callback Time, AJAX Throughput.

Targets

Browser alert rules are scoped by project (application). Select one or more projects as targets. Each project is evaluated independently — if two projects both breach the threshold, two separate incidents are created.

Filters

Browser metrics support optional page or AJAX URL filters to narrow the scope: - Page URL filter — for page load and Web Vitals metrics, restrict evaluation to a specific page pattern - AJAX URL filter — for AJAX metrics, restrict to a specific AJAX endpoint

How alert evaluation works

Operators

Operator Triggers when
above metric value > threshold
below metric value < threshold
equal metric value = threshold

Evaluation windows

Available durations: 5, 10, 15, 30, or 60 minutes.

Time functions

Function Behavior
all Triggers only if every 1-minute bucket in the window breaches the threshold. Prevents false positives from momentary spikes.
any Triggers if at least one 1-minute bucket breaches the threshold. Use for critical metrics where even a single breach matters.

Severity

Configure Warning and Critical thresholds independently. Both are evaluated on every scheduler tick.

Example configurations

Alert: Notify when average page load time exceeds 4 seconds for 5 consecutive minutes.

Setting Value
Metric Page Load Time - avg
Operator above
Critical threshold 4 seconds
Duration 5 minutes
Time function all

Alert: Warn on JS error spikes — more than 50 errors in any minute.

Setting Value
Metric JS Error Count
Operator above
Warning threshold 50 count
Duration 5 minutes
Time function any

Alert: Alert when LCP exceeds 2.5 seconds.

Setting Value
Metric LCP - Largest Contentful Paint
Operator above
Warning threshold 2.5 seconds
Critical threshold 4 seconds
Duration 10 minutes
Time function all