An extension is installable software Art. 3(1), Art. 2(1), Art. 3(22)
The CRA reaches products with digital elements made available on the market, which includes software the user downloads or installs. A browser extension is exactly that: code installed into the browser, almost always with a data connection. Publishing it to an extension store where EU users can obtain it is supply on the Union market.
Making available on the market covers supply in the course of a commercial activity, paid or free. A free extension that supports a commercial product is in scope just as a paid one is, so "we do not charge for it" is not the deciding factor.
Is an extension a "browser" under Annex III? Annex III Class I (2), Art. 7(1), Art. 7(4)
Annex III lists "standalone and embedded browsers" as an important product category in Class I. An extension adds functionality to a browser rather than being one, so it is very likely not itself caught by that item. That is a reasoned reading, not a certainty: the technical descriptions in Implementing Regulation (EU) 2025/2392 control what falls inside each category.
The safer approach is to look at the extension's own core functionality against the whole of Annex III, rather than assuming the browser item settles the question. Record the reasoning for whichever way you land.
Judgment call: Whether an extension counts as a browser, or as any listed category, is not spelled out in the CRA text itself. The implementing act's technical descriptions decide it.
When an extension is an important product Art. 7(1), Art. 32(2), Annex III
The category that bites is core functionality, not packaging. An extension whose core function matches a listed important category (a password manager, an identity or access management tool, a VPN, or anti-malware) is an important product, and its conformity route narrows accordingly. A general utility extension usually stays in the default category.
If your extension's whole reason to exist is one of those security functions, treat it as flagged and resolve the classification against the implementing act before choosing a conformity route.
Backend, obligations, and dates Art. 3(2), Art. 13, Art. 71(2)
Where the extension needs a backend you develop, or that is developed under your responsibility, and the extension cannot perform a function without it, that backend is in scope as a remote data processing solution. As manufacturer you meet the essential requirements, handle vulnerabilities, document, assess conformity, and CE mark. Reporting starts 11 September 2026; full obligations from 11 December 2027.