The tag
The snippet is about twelve kilobytes gzipped, loads asynchronously, and draws nothing but a floating launcher until somebody shows intent — hover, focus, touch or click. Only then does it create the iframe that holds the conversation. A page nobody chats on pays for one small script and nothing else.
Copy it from Channels › Website chat › Install on the agent, rather than from here: the page fills in your own key. Put it on every page you want the widget on, not just the home page — a customer with a question is usually deep in your site, on a product or pricing page.
Copy the snippet
Agents → your agent → Channels → Website chat → Install. The key in it is yours; the URL is the same for everyone.
Paste it before </body>
In your theme's footer, a global layout file, or a tag manager container that fires on all pages.
Publish, then run the check
The install check on the same page turns green once a real page load has reported in. It is reading the database, not your word for it.
On the platform you actually use
The install page has step-by-step instructions for Google Tag Manager, WordPress, Shopify, Webflow, Squarespace and React or Next.js, because the honest answer to 'where does this go' is different on each of them. If somebody else edits your website, the same page will email them the snippet and the instructions without you having to paste anything into a message.
Two copies of the script on one page is a common outcome of installing it twice — once in the theme and once in a tag manager — and it is harmless: the second copy notices the first and stands down rather than drawing a second widget.
Lock it to your domains
A new widget answers from anywhere, which is the right default while you are testing and the wrong one once you are live. Add your domains under Allowed domains, on the same Install page, and two things start enforcing it: the config endpoint refuses an origin nobody listed, and the page itself refuses to render inside a frame on an unlisted site.
A bare domain covers its subdomains, so listing example.com also covers shop.example.com. Add your staging host too, or you will lock yourself out of your own test environment.
Change how it behaves on one page
Most of the look and wording lives under Channels › Website chat — the Content, Style and Launcher tabs, beside a live preview — and applies everywhere. When one page needs to differ, put the difference on the tag: the side it sits on, its colour, its label, its offsets, its z-index, whether it hides on mobile, whether it opens full-screen on mobile, and whether it opens by itself. Each of those beats the saved setting, on that page only.
You can also drive it from your own buttons. Any element marked to open, close or toggle the widget does so with no JavaScript from you at all, and an open action can carry a question to prefill — a 'Ask about shipping' link on a product page opens the widget with the question already typed.
When visitors are signed in
For a widget on pages behind your own login, you can tell us who the visitor is in a way they cannot forge: your server signs their user id with the widget's identity secret, and the page passes the signature along. A verified visitor whose email your server signs as well is keyed to that address, which puts their chats on the same contact as the threads they started by mail. This is the only matching across channels: anonymous visitors, callers and emails are each their own contact. The agent is also given the name and email the page passes, as details to use instead of asking again. Unless your server signs the email too, the agent treats them as information the website supplied, not as proof of who the visitor is.
It is off unless you set it up, and a widget with no secret behaves exactly as an anonymous widget always has. If the widget should only ever appear behind your login, you can also require identity outright and have it refuse anonymous visitors.