Inject CSS and JavaScript that comes back every visit

CSS, JavaScript and HTML. It's one code field that Hoverify parses as HTML, so styles go in wrapped in a style tag and scripts in a script tag. Anything in a script tag really runs, so this isn't a CSS-only tool.

That's the point of it. A snippet is saved with a name and a list of hosts, and Hoverify re-applies it on every visit to those hosts until you switch it off. Fix a site's unreadable font once and it stays fixed.

Each snippet carries its own list of hosts. An entry matches a host exactly, or matches one full URL exactly, or you can use * to run it everywhere. There's no pattern matching beyond that, so a snippet for several subdomains needs each one listed.

The editor re-runs your code shortly after you stop typing and shows it on the page underneath, so you're writing against the real site rather than against a guess about it.

Hiding a nag banner or a cookie wall that won't stay dismissed, enlarging text on a site that ships it too small, adding a keyboard shortcut a site never built, or trying a copy change on production before anyone commits to it. Forcing dark mode on a site that has none is the worked example.

This one sits in the same extension as the CSS inspector, which is the difference that matters in practice: hover an element, take the selector it gives you and paste it straight into a snippet. Writing a per-site override is two jobs, finding the target and writing the rule, and this does both in one place.

Yes. Every tool runs in the Firefox build; it carries an experimental label because Chromium gets fixes and new features first. Chrome is the fully supported browser, along with Chromium forks like Edge and Brave.

Custom Code is part of Hoverify, a paid extension with a 14-day refund. That's how you try it, since there's no separate trial tier. A license runs in 3 browsers at a time, and it won't renew itself. See the pricing.