Which Squarespace plans support it?

Plans that include code injection. Squarespace lists this on its plan comparison page.

Can I add it to one page only?

Use page-level code injection, or keep the site-wide pixel and use page targeting rules in the widget.

Yes on storefront pages. Use widget targeting to keep widgets away from checkout.

Injected code may not run in the editor. Check the live site in a private window.

To add AutoSocialProof to Squarespace, paste your campaign pixel into the Header field of Code Injection, which adds it to every page of the site.

You need: A Squarespace plan that includes code injection, and your campaign pixel from the AutoSocialProof dashboard.

Paste before </head>

<script defer src="https://app.autosocialproof.com/pixel/YOUR_PIXEL_KEY.js"></script>

Open your site and go to the Code Injection panel (in recent versions under Website, Pages, Custom code; in older versions under Settings, Advanced).
Paste your AutoSocialProof pixel line into the Header field.
Click Save.
Open your site in a private window and check that a widget appears.

Menu names can change. Squarespace's own help: official guide.

Code injection is not available on every Squarespace plan. If the field is locked, your plan does not include it.

Squarespace may disable injected code while you are logged in to the editor; test logged out.

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