Three quick checks tell you whether the snippet is installed correctly.
Nothing here needs a build tool or a testing framework, just DevTools.
1. The config object is there
Open your site in a fresh tab. Open DevTools (F12) and, in the Console, type:
You should see an object with your site id and a version number. Something
like:
If it prints undefined, the snippet did not load. Check that:
- The
<script> tag is actually in <head>, view page source, do not
trust an in-page editor’s preview.
- The snippet is the first script tag. If it is below GTM or an
analytics tag, move it up.
- Nothing is blocking
cdn.abtestly.com. Try incognito with extensions
disabled. Some ad blockers need cdn.abtestly.com allowlisted.
- The snippet on the page matches the snippet in the dashboard. Site
snippets are keyed to the domain they were generated for.
2. The exposure beacon fires
If you are on a page that a running experiment targets, you should see a
POST to api.abtestly.com/e in the DevTools Network tab. It is a small
text/plain request, that is deliberate; it lets sendBeacon work
without a CORS preflight.
No experiment matches this page? That is fine, the config object above
tells you install is working. Create a “test” experiment that targets the
current URL and reload.
3. The dashboard says so
Back in the dashboard, open the site. If the snippet is not detected yet,
you see a banner at the top of the Experiments tab with a copy of the
snippet inline for convenience. Once the first beacon arrives, that banner
disappears and every experiment on the site starts showing accurate
collection status.
If a site was collecting yesterday and stopped today, the same banner comes
back with a different message (“Snippet not detected since X”). That
usually means the tag was accidentally removed or a deploy did not include
it. See Troubleshooting → Snippet not firing
for the diagnostic ladder.
Bonus: the dev debugger
For anything deeper, which variant was picked, why a click activation did
not fire, what the last five beacons contained, call the dev debugger from
the Console:
The full API for that is on the dev debugger page. Last modified on August 1, 2026
