Your styles and scripts
on every site,
on every device.
Hide ads and cookie banners, add keyboard shortcuts, debug GTM, build a QA toolbar — without waiting for the site author. Injected CSS and JavaScript works instantly, syncs across devices, can be shared via a link with 1–48 h TTL.
Free · no account · 2-minute install · Chrome 100+Six pillars of JustZix
Inject CSS and JS
Create rules for domains and URL paths. Hide banners, fix layouts, add custom logic. Full control over every site you visit.
Dev tools on the page
CSS and JS editors, a REPL console and a log & network viewer — windows rendered straight on the page. Plus an action panel with buttons, sliders and toggles. A mini-IDE instead of DevTools.
Cross-device sync
One sync key, the same rules on your PC, laptop and work computer. Change in one place — instantly everywhere.
Share via link
Send a friend a short link — they get a preview of your rule set and import it with one click. Links expire after 1, 6, 12, 24 or 48 hours.
AI assistant inside the extension
The built-in AI Helper (OpenAI, Anthropic or Gemini) inspects the page, writes CSS and JS, tests the code in TEMP windows and fixes its own errors. Once you approve, it creates rules, action bars and buttons.
Four browsers, one extension
JustZix runs on Chrome, Firefox, Edge and Opera — the same feature set in each. Free, no account, no telemetry: download the ZIP and load it as an extension.
What it is good for
Three most common scenarios. Full list — with copy-paste code — in the Use cases section.
Latest on the blog
Fresh tutorials, deep-dives and quick wins — all with ready-to-paste code for JustZix.
How to get started
Install the extension
Download the ZIP and load it as an unpacked extension in Chrome — full instructions on the "Download" page.
Create your first rule
Define a URL pattern and the CSS/JS code to run on matching pages.
Sync and share
Sign in on another device with your sync key, or send a friend a share link.