Browser Checks for your JavaScript App

Before OnlineOrNot: Customers tweeting you, emailing you, calling you, wondering why your website doesn't work.
With OnlineOrNot: Reliable downtime alerts (for you/your customers), letting you fix issues before they impact your reputation.
See Plans and Pricing

No time limit, and no credit card required.

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)

Global Monitoring

Monitor from any one of 18 major cities around the world. Check out our supported regions.

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.

What others are saying about OnlineOrNot

Don't just take our word for it, see what our customers think.

    • Bet on indie hackers 🚀

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

      Thought that his tool was wrong as uptime robot didn't reported those downtime.

      Turned out it was the other way.

      Khaled Bentoumi
      Founder of Data to Page
    • OnlineOrNot does the job for me.

      Charles Miller
      Software Architect at Atlassian
    • 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! 👏👏

      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
Ready to get going? Let's go:

No time limit, and no credit card required.