My browser toolbar is a row of Chrome extensions, and most of them earn their place during SEO audits. They check redirects, headings, rendered HTML, page speed and tech stacks without making me leave the page I'm looking at. Over a working week, that saves hours.
This list gets a clear-out every so often. Tools get abandoned, handy features move behind paywalls, and Google quietly retires things like AMP. What follows is what I actually use for SEO work, what each one is good for, and the catches worth knowing before you install.
1. Detailed SEO Extension
If you install one extension from this list, make it this one. Detailed SEO Extension opens a single panel showing the page title, meta description, canonical, indexability, hreflang, heading structure, schema, Open Graph tags and image alt coverage.
On an audit I use it as the first check on any page: is it indexable, does the canonical point where it should, is the heading order sane. Three clicks instead of three tools, and it's genuinely free - no account, no upsells, no tracking.
2. Redirect Path
Redirect Path sits next to my address bar and flags the HTTP status of every page I land on. A 301, a 302, a 404, a sneaky JavaScript or meta-refresh redirect - the icon changes, and a click shows the full chain.
Redirect chains are easy to miss and slow to find by hand. This catches them while I'm just browsing a site, so I spot them long before they reach a report.
3. Link Redirect Trace
Redirect Path tells you a page redirected. Link Redirect Trace, from LinkResearchTools, tells you what happened at every hop - the status code, whether robots.txt blocked it, whether a noindex tag sat in the chain, and how link equity passed along the way.
I reach for it when a redirect is misbehaving and Redirect Path's quick view isn't enough to explain why. It's free; a LinkResearchTools account adds deeper link metrics on top.
4. Ahrefs SEO Toolbar
The Ahrefs SEO Toolbar overlaps with Detailed SEO Extension but brings different strengths: an on-page report, a redirect tracer, a broken-link highlighter, an hreflang checker and a SERP overlay. The core features are free; an Ahrefs subscription adds traffic and backlink metrics on top.
I keep both installed. Detailed for a fast read of one page, Ahrefs when I want broken links surfaced or a closer look at a set of search results.
5. HeadingsMap
HeadingsMap draws the heading structure of a page as a clean outline, so a missing H1 or a jump from H2 straight to H4 is obvious at a glance. It also reveals headings hidden with CSS and follows the HTML5 document outline.
Sensible heading structure helps both search engines and screen readers, and it's one of the quickest on-page checks going. HeadingsMap turns it into a five-second job.
6. View Rendered Source
Modern sites build a lot of their content with JavaScript, and what sits in the raw HTML often isn't what Google ends up indexing. View Rendered Source shows the raw HTML and the rendered HTML side by side, with the differences highlighted.
If a client's key content, internal links or canonical tags only appear after rendering, that's a JavaScript SEO problem worth flagging, and this is the quickest way to see it. Install it from the Chrome Web Store rather than searching for its website - the original domain was lost to a squatter.
7. Quick JavaScript Switcher
Quick JavaScript Switcher turns JavaScript on and off for the current site in one click. It pairs neatly with View Rendered Source: switch JavaScript off, reload, and see how much of the page actually survives.
It's one of the first checks I run in an audit. If the navigation, the main copy or the internal links vanish without JavaScript, search engines are working harder than they should to find them.
8. Wappalyzer
Wappalyzer tells you what a site is built with - CMS, ecommerce platform, CDN, analytics, frameworks, server software. The icon updates as you browse, so a glance tells me whether I'm looking at WordPress, Shopify or something custom.
That matters early in an audit. Knowing the stack tells me which fixes I can hand straight to a client and which will need a developer.
9. Wayback Machine
The Internet Archive's Wayback Machine extension does two useful things. When a page returns a 404 or another error, it offers the most recent archived version instead. On any live page, it gives one-click access to how that URL looked at points in the past.
I use it to see what a page said before a client redesign or migration, to recover copy that was dropped along the way, and to check when a competitor changed direction.
10. META SEO Inspector
META SEO Inspector reads all the metadata on a page without sending you into the source code: title, meta description, canonical, robots directives, Open Graph, Twitter cards, structured data and more. It flags anything missing or malformed as it goes.
Detailed SEO Extension covers a lot of the same ground. META SEO Inspector earns its keep when I need to pick apart exactly how one page is marked up.
11. Check My Links
Check My Links crawls every link on the page you're viewing and colours them in: valid links green, broken ones red. There's no report to read - you just see the problems.
It's quick for catching broken internal links during an audit, and it's a long-standing favourite for broken-link building - find a dead link on someone else's page, then offer your content as the replacement.
12. Hreflang Tag Checker
If a site serves more than one language or country, hreflang tags are easy to get wrong and hard to check by eye. Hreflang Tag Checker reads the whole hreflang cluster for a page and validates it: are the language and country codes valid, does each version point back, is the page referencing itself.
SEO Minion, further down this list, runs a basic hreflang check. This one goes further by following the return links across every alternate version, which is where most hreflang problems actually hide.
13. MozBar
MozBar shows Moz's Domain Authority and Page Authority on any page or set of search results, alongside link metrics and a quick on-page overview. It's a fast way to size up a domain or read the competition in a SERP.
Since early 2025 the free version is much tighter. DA and PA are still free within a monthly limit, but most of the deeper analysis now needs a paid Moz Pro account. For authority scores at a glance, the free tier still does the job.
14. SEOquake
SEOquake, made by Semrush, overlays SEO metrics on every search result - domain and page-level scores, backlink counts, traffic estimates and domain age. It also runs a quick on-page audit, shows keyword density, and exports a SERP to CSV.
It covers similar ground to MozBar, with one practical edge: that CSV export. When I want a search results page as a spreadsheet to work from, SEOquake gets it there in a couple of clicks. The core features are free.
15. SEO Minion
SEO Minion is a free, no-login bundle of small jobs that would otherwise take several tools. It runs an on-page analysis, checks hreflang, previews how a page looks in the SERPs, finds broken links, and simulates a Google search from another location.
The location simulator earns its place on its own. Rankings shift by country and city, and checking them from where the user actually sits beats guessing.
16. SimilarWeb
SimilarWeb gives a fast read on any site's traffic: estimated visits, where they come from, top keywords, the geographic split, and - more recently - how much of that traffic arrives from AI tools like ChatGPT.
The numbers are estimates, so I treat them as direction rather than fact. For sizing up a competitor or a prospect before a deeper look, they're a useful starting point.
17. Tag Assistant
Google's Tag Assistant checks whether your Google tags are firing correctly - Google Analytics 4, Google Ads and Tag Manager. It records a session, then shows which tags fired, in what order, and with what data.
Tracking that looks fine but isn't is a quiet, expensive problem. Tag Assistant is how I confirm a GA4 or Tag Manager setup is doing what the client thinks it is. If you remember the old Tag Assistant Legacy extension, this is its replacement.
18. User-Agent Switcher and Manager
User-Agent Switcher and Manager loads a page as a different browser, device or crawler. Switching to a Googlebot user-agent shows roughly what Google is served; switching between mobile and desktop is quicker than resizing a window.
Chrome's built-in device mode covers some of this, but for a fast user-agent swap mid-audit a dedicated extension is less fiddly. The long-standing favourite used to be "User-Agent Switcher for Chrome" - this is the actively maintained one to use now.
19. Data Scraper
Data Scraper - you may know it as Data Miner - pulls structured data such as tables, lists and search results off any web page and drops it into a spreadsheet, no code required. For SEO I mostly use it to grab URL sets from search results, whether that's mapping what Google has indexed for a client or building a quick competitor list.
20. Keyword Surfer
Keyword Surfer, from Surfer SEO, drops search volumes, CPC and related keyword ideas straight into Google's results pages. It's the obvious free counterpart to Keywords Everywhere - Surfer has committed to keeping the core data free, with no account needed.
It won't replace a proper keyword research tool, but for a quick sense of demand while you're already looking at a SERP, it does the job at no cost.
21. Keywords Everywhere
Keywords Everywhere shows search volume, CPC and competition data inside the results pages of Google, YouTube, Search Console, Google Trends and plenty of other sites. It's useful context while you're already looking at a SERP.
It stopped being free back in 2019, though. It now runs on paid credits, so it's only worth installing if you'll use it enough to justify the cost. For lighter use, Keyword Surfer above covers much of the same ground for nothing.
What dropped off the list
A few extensions that earned a place in older versions of this post have gone:
- The Lighthouse extension - the audit itself is as useful as ever, but the standalone extension was retired. Lighthouse now lives inside Chrome's developer tools: press F12, open the Lighthouse tab, and run it from there.
- AMP Validator - Google stopped treating AMP as a ranking factor and dropped the AMP requirement for Top Stories. Unless a site still actively serves AMP pages, there's little reason to check them.
- Standalone Google Analytics debuggers - most were built around Universal Analytics, which stopped collecting data in 2023. Tag Assistant covers GA4 debugging now.
- Open SEO Stats - it still installs, but it's looking dated, and the all-in-one extensions at the top of this list now cover the same quick checks more reliably.
Get more from your browser
That's the working set - the extensions I reach for on a real audit, not a list assembled for the sake of one. Install the ones that fit how you work, and your browser will do more of the legwork for you.
Want the audit without the toolbar? Aira's SEO team does this for a living, technical SEO included. And once you've made your fixes, our SEO checklist is a good way to keep pages in shape.
