ブラウザー拡張機能とは

Ad blockers and password managers live inside your browser as extensions — small programs that customize and enhance how you browse.

A browser extension is a mini-app running inside your browser, adding features or tweaking sites. Think superpowers your browser lacked out of the box.

Extensions personalize the web: they save time, boost productivity, add security, and reshape how sites look — making the web work for you.

You probably use extensions already: ad blockers, password managers, grammar checkers, dark mode. Each quietly reshapes your browsing.

Extensions integrate deeply — reading and changing page content, working with tabs and bookmarks, even running background tasks.

One key power is touching page content: adding buttons or sidebars, highlighting items, or blocking elements. That's how ad blockers work.

Beyond pages, extensions use browser APIs to manage tabs, control downloads, or read history (with permission) — at the browser level.

Because they are powerful, extensions need explicit permissions from you. Always review what an extension asks for and trust its developer.

Chrome and Edge extensions follow the Manifest V3 spec — it defines how they are structured, what they can do, and how they reach the browser.

Extensions are small, powerful programs that customize browsing, touch page and browser features, and require your permission. Next, the setup!