Browser Checks for your
JavaScript app.

Know when your JavaScript app breaks, before your customers do.

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Trusted by thousands of businesses

OnlineOrNot's dashboard

How it works

OnlineOrNot builds website monitoring tools - the first of which was a uptime checker.

After running a few million checks, my customers were asking why I didn't support Single Page Applications (SPAs) like React - and the answer was pretty simple: the basic uptime checker is better suited for static pages.

With OnlineOrNot's Browser Checks (powered by Puppeteer), you can now reliably check whether your React (or Vue, or Angular, or whatever comes next) apps successfully render, and display the text you expect.

Browser Checks supports:

  • Loading your web app
  • Searching for text on the page
  • Retrying, and waiting for several failed checks before alerting
  • Sending alerts to Email, Slack/Discord, SMS, and Webhooks when things go wrong


Real Browsers

Browser Checks are run in real Chrome browsers, isolated from each other for extra security.

Verified Alerts

Each failed check gets retried, and re-checked in separate regions before sending you an alert.

Alerts where you need them

Get notified when your check starts failing and when it works again via SMS, Email, Slack, and Webhooks.

Text Search

Search your page for text to catch blank pages that don't display obvious errors (such as React, Vue and Angular apps)

Bring the whole team

Monitoring is your whole team's job, not the responsibility of just one person. Bring your whole team at no extra cost.

People ❀️ OnlineOrNot

OnlineOrNot is built for scale and runs millions of uptime checks every week. Thousands of sites, startups and some of the world's leading brands have already made the switch from other uptime monitors.

Uptime Checks last week
Detected incidents last week
    • OnlineOrNot has been absolutely fantastic for my bot, Noti. It completely transformed the way I monitor online services.

      The real-time notifications keep me in the loop about any downtime, allowing me to take immediate action. If you're looking for a reliable way to monitor your project's status, I highly suggest using OnlineOrNot.

      Adam H
      Maker of Noti
    • Bet on indie hackers πŸš€

      I tried @RozenMD's OnlineOrNot uptime monitoring, and for a few days got notifications of 2min down time.

      I thought that OnlineOrNot was wrong as Uptime Robot wasn't reporting anything.

      Turns out it was the other way around.

      Khaled Bentoumi
      Founder of Data to Page
    • We've been using OnlineOrNot and it has been a life saver.

      It, by far, has been one of the most responsive uptime services we've tried and it only gets better and better as time goes on.

      Alex Bowles
      Founder of Casterlabs
    • I just set up some site aliveness checks for @Archium_io with @RozenMD's OnlineOrNot.

      Took me less than five minutes and it was completely self-explanatory, not to mention gorgeous. Seriously good experience.

      Great job, Max! πŸ‘πŸ‘

      Graham Lea
      Founder of
    • OnlineOrNot by @RozenMD is all one needs

      It is easy to set up and very reliable. I have been using it for almost an year now.

      Rajat Saxena
      Founder of CourseLit
    • I'm using OnlineOrNot to monitor my @cloakist customers' sites, so I can respond quickly if they stop working

      Love it. Super clean interface, very intuitive. Particularly impressed at how it can wait for full page load

      Thanks @RozenMD for making this awesome tool!

      Louis Barclay
      Founder of Cloakist
    • OnlineOrNot does the job for me.

      Charles Miller
      Software Architect at Atlassian
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