Site speed monitoring for developers: data you can trust

Lighthouse and PageSpeed Insights use simulated throttling to test your website. The data is actually always collected on a fast connection!
DebugBear actually slows down the network instead of relying on a simulation that's often inaccurate.
DebugBear always repeats tests before sending an alert, so you don't have to deal with issues you can't replicate.
We track everything from Web Vitals to Lighthouse scores and page weight. We also provide debug data for each metric to help you improve it.
Want to optimize the Largest Contentful Paint? No problem! We'll show you the responsible DOM element and what network requests you need to speed up.
What requests are render-blocking? Are any resources preloaded? Does the LCP image use the fetchpriority attribute? How is bandwidth allocated across requests?
Our waterfall chart shows all of this information and puts it into context.
Wondering why your LCP went up? Simply click on the regression in the chart to see what changed between the two test results.
Configure custom alert thresholds and make sure your pages stay in budget.
Run tests in controlled lab environment and get in-depth reports.
See how fast your website is for real users, and what you can do to optimize it.
Real user data from the Chrome User Experience Report.
Generate specific, actionable fix instructions based on your test results. Just paste the prompt into Claude Code, Cursor, or your preferred AI coding agent.
Each prompt includes the specific resources and issues found on your page, so the AI agent can make targeted changes.
Send alerts by email, in Slack, or in Microsoft Teams.
Trigger page tests with the API and save test results to your own infrastructure.
Catch regressions early by testing every pull request and deployment.
Download metrics as CSV or JSON.
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