Make it work.

Make it fast.

Make it enjoyable.

CatchJS packs JavaScript error tracking, web performance monitoring and time on page reporting in one tiny, but powerful package.

JavaScript error tracking

Be notified when your web app breaks and see the full context of the error so you can fix problems quickly.

Performance monitoring

Build a blazingly fast experience. Track web performance metrics, including Core Web Vitals, to ensure high performance on all your pages.

Time on page reporting

Know where your customers are spending their time, by measuring how long each page is visible in a browser.

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Trusted by top teams

CatchJS has processed billions of events for customers around the world.

The product is great and the customer service is fantastic as well.

—Remi Silva, Blanktag

Dead simple integration

Just add the following script tag, set up an account, and you are ready.

<script src=""></script>

The CatchJS script will set up error reporting and performance monitoring directly from your users' browsers. It will automatically collect uncaught exceptions, performance metrics and time on page analytics. Read more about setting up CatchJS.

Can your site break without your knowledge?
A majority of bugs existed for more than 180 days before they were first reported by a user, in one study of open source software. Source: Thung et al. (2012), "When would this bug get reported?"

Build remarkably high-quality experiences by staying on top of any error that happens. With JavaScript error monitoring on your site, you'll be notified whenever a new type of error occurs.

See the code where the error happened. Source maps are automatically applied.
Capture errors along with their stack trace. The source code is automatically downloaded, and source maps are automatically applied.
Screenshots can be captured automatically, along with the clicks that lead to the error.
Pinpoint when problems started.
Pinpoint when problems started occurring, and where they happen. Errors are charted by time and by page.
See in which browsers an error is happening .
See in which browsers a particular error happens.
Log any data with catchjs.log().
Using the catchjs.log() API, you can log any data. It's like the developer console but logging from your users browsers.
How many of your users have a slow experience?
Core Web Vitals directly affect search engine rankings. Source: (2021), "More time, tools, and details on the page experience update"

Build a fast website. Monitor the user experience on your pages, with performance metrics like the Core Web Vitals. Analyze where the time is being spent via the page load timeline.

See where time is spent with the page load timeline
See where the browser is spending its time with the page load timeline. The timeline shows the steps to the load event, split into DNS and redirect time, connection time, server time and client time.
See Core Web Vitals for all pages.
See Core Web Vitals for all your pages. The histogram shows the distribution of timings. The Core Web Vitals are Largest Contentful Paint, Cumulative Layout Shift and First Input Delay. CatchJS will also track First Paint and First Contentful Paint.
Get detailed statistics, including percentiles and histograms for the tracked metrics.
See detailed statistics for all the tracked metrics. Go beyond tracking averages, and use statistically robust measures like percentiles. Use the histogram to see the distribution of timings.
Determine which pages to prioritize in the performance overview.
See at a glance which pages are fast, and which pages need more work. You can compare percentiles for all pages on all metrics.
Where do your users spend their time?

Time-on-page measurements let you know how long pages are open in your users' browsers, so you can see where people actually spend their time.

See how time spent on page changes over time.
Understand how changes to your site impact the time spent on a page by looking at the changes over time.
Measure the time spent on each page.s
Learn what content resonates with your users, and what doesn't, by measuring how long each page is open in the browser.
See what pages are popular via pageviews.
See what content is popular, and what it isn't, by the pages' pageview counts.
Track pageviews over time.
See how the popularity of a page changes over time, by inspecting the pageview timeline.

All of the features, none of the bloat

Make it fast. Don't let error tracking and performance monitoring slow things down. The CatchJS script is up to 20 times smaller than our competitors, less than 1.8KB after compression.

CatchJS vs competitors (lower is better)
KB 28 20 12 4
Other error trackers
Other perf. trackers
GDPR ready

Preserve user privacy

We'll monitor your website, but not your users. CatchJS does not make any attempt at tracking users, neither through IPs or cookies or anything else. Since CatchJS doesn't track personally identifiable information, you don't need to add a consent pop-up to use it. Read more.

We're a lot cheaper than having a broken web app

There are no hidden costs and no surprises, just a flat monthly rate.


per month

  • Free 14-day trial
  • 1 000 logged errors per month
  • 1 000 log API calls per month
  • Performance metrics for 100 URLs
  • Time on page for 100 URLs
  • Pageviews for 10 000 URLs
  • 1 domain per account
  • Email notifications
  • Screenshots
  • Click trails
  • Priority support
Start 14-day free trial


per month

  • Free 14-day trial
  • 100 000 logged errors per month
  • 100 000 log API calls per month
  • Performance metrics for 1 000 URLs
  • Time on page for 1 000 URLs
  • Pageviews for 100 000 URLs
  • 1 domain per account
  • Email notifications
  • Screenshots
  • Click trails
  • Priority support
Start 14-day free trial


per month

  • Free 14-day trial
  • 1 000 000 logged errors per month
  • 1 000 000 log API calls per month
  • Performance metrics for 10 000 URLs
  • Time on page for 10 000 URLs
  • Pageviews for 1 000 000 URLs
  • 25 domains per account
  • Email notifications
  • Screenshots
  • Click trails
  • Priority support
Start 14-day free trial
Are you part of an open source software project? We have much gratitude to the open source software community, and therefore provide a free subscription to such projects. Click here to apply.