Web app monitoring that shows what user did before the BUG happened

Find, triage and recreate bugs 100% automatically

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Drastically reduce bug lifetime with automatic discovery and replay

Immediately learn about bugs

Immediately after the new release you get Slack notifications about the new problems. Kuoll smartly merges JavaScript errors by stack traces.

Triage bugs in minutes

With Kuoll dashboard see how many users are affected by specific bugs. With Kuoll, in a minutes after the new release you understand the impact of each bug.

Debuggable user sessions

Each Slack bug notification comes with link to a replayable user session. Each session shows both how user interacted with the web page and also how the code was running in the end user machine.

It's pretty much the same information that developers see in the web browser developer's tools. Kuoll is like a time machine that allows you to see and investigate what was wrong on the user machine in the moment she had a problem.

Install and use

Web app monitoring and customer support automation is easy with Kuoll. You may also try online demo without registration. It shows the complete and hardcore overview of Kuoll features.

Create account

Create account to get your Kuoll APIKEY.

Copy-paste code snippet

Copy code from the API introduction page. We have async, sync and npm-based version available.

Feel free to contact us if you have a smart or a silly question.

Run the web app

Run your new build in local development, staging and production environment.

Add bot to your Slack

Bugbot by Kuoll will send a notification each time it find unfamiliar js error or unfamiliar errorneoues server reply. Each notification has link to the replayable debuggable user session.

See the user sessions

Replay user session and learn how the user event caused network request, HTML DOM changes, and JS system API calls.

Core technology

Kuoll JavaScript code records debuggable user sessions and monitors a web application. When Kuoll code detected JavaScript Errors and server XHR error replies (and some other bugs) then it dumb debuggable user session to the Kuoll server.

When a problem detected, Kuoll dumps the user session to the server. If it's the first time this bug happened then Kuoll sends notification about the new issue. On the dashboard you can see how many time each Error happened in the web app and how many users affected by each issue.

Each user session shows the developer

  • user events,
  • replayable DOM-mutations,
  • network requests (with a complete headers and content),
  • JavaScript execution flow, including calls and callbacks of Promise, setTimeout, setInterval methods.

All these events are connected to the cause-effect chains. This way, a developer doesn't need to reproduce bugs. The complete and authentic cause-effect chains provide all information a developer needs to analyse and fix bugs. is able to see and analyse the bug on the record, without even reproducing it, and fix the issue xtremely fast.

The core and special recording script is our precious highly optimized snippet of client-side JavaScript code.

Kuoll crushes bug fixing cost in all stages of bug fixing

Bug! Gather info Report Reproduce Analyse Fix Deploy
The old way
Customer reports a problemCustomer support talks to customerCustomer support reports an issueDeveloper recreates environment and reproduces the problemDeveloper analyses the issueDeveloper fixes the issueDevOps deploys a fix to production
The Kuoll way
Kuoll script detects a problem Kuoll script captures bug report automaticallyKuoll script captures high-fidelity bug reportKuoll replays captured report in debug modeDeveloper analyses the issue with easeDeveloper fixes the issue with confidenceDevOps deploys sure fix to production
Biz Value
Finds bugs before your customers doAutomated capturing saves 68% customer support timeHigh-fidelity capturingHigh-fidelity replaySure fix, no refix ping-pong, saves 40% timeMuch easier, spends 60% less timeBugs fixed, HQ software is direct to market

Privacy and sensitive data

In Kuoll we highly respect customer and end user privacy. We do not sell and do not transfer our customer's or end user's data to third parties.

To exclude private user data from the record, please list the private XHR URLs in the parameter ignoreUrls parameter of the Kuoll API startRecord function.

See Kuoll acceptable use and privacy policy for more details.

The ultimate solution of the privacy question is on-premise deployment. This means you can host Kuoll on your own servers in your secured environment. To get a quote about this option, please contact Kuoll on-premise sales.