Browser alerts - Atatus Docs

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	None
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, so 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 with 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

​Available metrics

​Page load metrics

​Core Web Vitals

​AJAX metrics

​Transaction metrics

​JavaScript errors

​Baseline metrics

​Targets

​Filters

​How alert evaluation works

​Operators

​Evaluation windows

​Time functions

​Severity

​Example configurations