Ranked by what you actually get without paying or signing up, plus an honest look at which "free" tools wall everything behind a login, and which survived Manifest V3.
The honest problem with free-SEO-tool lists is that "free" hides three very different things, and the difference decides whether a tool is actually useful to you:
This ranking weighs the first kind highest. A tool that shows real data the moment you install it beats a "free" tool that makes you sign up and then rations what you see. (For the strict ranked, account-by-account comparison, our compare page goes deeper on the head-to-heads; this page is the broader Chrome listicle and the login-wall reality check.)
| # | Extension | Best free feature | Account? | Real free value |
|---|---|---|---|---|
| 1 | Ahrefs SEO Toolbar | On-page audit + redirect tracer | None | High |
| 2 | SEOquake | SERP overlay + CSV export | None | High |
| 3 | Detailed SEO Extension | Clean on-page meta & heading audit | None | High |
| 4 | Keyword Surfer | Volumes in Google results | None | Good |
| 5 | SEO META in 1 Click | All page meta at a glance | None | Good |
| 6 | SEO Minion | Hreflang & SERP preview | None | Good |
| 7 | MozBar | DA/PA on every page | Free login | Good (gated) |
| 8 | Keywords Everywhere | Volumes everywhere | Paid credits | Limited free |
One rule above all: value you get without an account or a credit card, the same framing this site has always used. Then breadth of useful features, whether it works under Manifest V3, and whether it's actively maintained. We don't score on invented accuracy figures, every tool's volumes and authority numbers are modelled estimates, so we rank on access and capability, not on a precision we can't verify.
The most free value of any SEO extension, and you don't even sign in. On-page SEO report, redirect/HTTP-header tracer, broken-link checker, and a SERP overlay with core metrics, all without an Ahrefs account. It's the foundation of any free stack. The honest limitation: the deepest backlink and keyword numbers still need a paid Ahrefs subscription, but the free toolbar alone covers most day-to-day checks. Full review · SEO Toolbar guide.
The best free SERP overlay: authority scores, traffic estimates and a one-click CSV export of search results, no login required. Toggle it on for research sessions and off the rest of the time. The honest limitation: the on-page panel can feel cluttered, and the metrics come from Semrush's model, so treat them as directional. Full review.
A favourite among SEOs for good reason: one click shows the page's title, meta, canonical, headings outline, indexability, schema and internal/external links, laid out clearly with no noise. It's the quickest way to sanity-check a page's basics. The honest limitation: it's deliberately on-page only, no SERP or keyword data, so it complements rather than replaces Ahrefs or SEOquake.
Adds estimated search volumes and related keywords directly into Google's results page, the easiest free keyword-research workflow there is. The honest limitation: volumes are estimates and Chrome-focused, with no Firefox build. Full review.
Click once and get every meta and header value on the page, titles, descriptions, Open Graph, headings, image alt coverage, in a tidy panel. Overlaps with Detailed; pick whichever layout you prefer. The honest limitation: like Detailed, it's a page-inspection tool, not an analysis suite.
Handy for international SEO, its hreflang checker is the standout, plus a SERP preview tool and on-page analysis. The honest limitation: some bulk features are slower than dedicated tools, and it's Chrome-mostly.
MozBar shows Moz's Domain Authority and Page Authority on every page and in SERPs, the metric many link builders still reach for. It's free, but you must create a Moz account to use it, which is why it ranks below the no-account tools despite being genuinely useful. The honest limitation: beyond DA/PA, the deeper data needs a paid Moz plan. Ahrefs vs MozBar · MozBar review.
Once fully free, Keywords Everywhere now runs on a paid-credit model, so it's included here only with that caveat. It surfaces volumes, CPC and related terms across Google, YouTube, Amazon and more, genuinely handy, but it's no longer a free tool in the sense the others are. The honest limitation: the free allowance is minimal; budget for credits if you rely on it.
A common 2026 worry, worth clearing up. Manifest V3 (Chrome's extension overhaul) genuinely disrupted ad blockers, because it limited the request-blocking API they depended on; that's why the full uBlock Origin left Chrome. But SEO extensions mostly read and display page data rather than block network requests, so the change barely touched them. Ahrefs Toolbar, SEOquake, Detailed, Keyword Surfer and the rest all run fine under MV3. If you've seen "is [SEO tool] dead after Manifest V3?", the answer for these is no, the MV3 casualties were content blockers, not SEO toolbars. The one thing to do is keep extensions updated so they're on their current MV3 builds.
You don't pick one, you layer a few and toggle the noisy ones:
Total cost: zero. Combined, that covers on-page audits, redirect tracing, SERP authority, search volumes, DA/PA and hreflang, the same coverage paid suites charge for, minus the depth.
"Free SEO extension" is a phrase clones love, because SEOs install lots of tools quickly. Stick to the official publishers (Ahrefs, Semrush for SEOquake, Moz), and be wary of unknown extensions promising "free Ahrefs data" or "unlimited keyword volumes", those are exactly the kind of high-permission lookalikes worth checking first. Run anything unfamiliar through our Extension Safety Checker.
Ahrefs Toolbar, SEOquake, MozBar and Wappalyzer all have Firefox builds; Keyword Surfer, Detailed and SEO Minion are Chrome-mostly. The Chromium browsers (Edge, Brave, Opera, Vivaldi) install everything here directly from the Chrome Web Store. Safari is the most limited, the Ahrefs Toolbar is the notable tool with an official Safari version. For a Firefox-specific breakdown, see our SEO extensions for Firefox guide.