7 Free Browser Extensions for SEO

7 Free Browser Extensions for SEO

Great SEO is often all about the tools you’re using and your understanding of them. There’s a large number of paid tools that can deliver solid data but, can you get a similar result just by using the free ones? It is a lot harder but, you can get some good results nevertheless simply by using free browser extensions for SEO.

SEO extensions can be highly useful since they are more efficient since you don’t need to open another web page or offline application. We compiled a list with a few great free browser extensions that can surely help you out in regards to SEO.

One warning before you start installing things: an extension is a shortcut, not a source of truth. Almost everything a toolbar shows you is either a third-party estimate (traffic, authority scores, keyword volume) or a snapshot of a single page at a single moment. Use extensions to decide what deserves a closer look, then confirm the decision in Google Search Console, in your analytics, or in the page source itself. The seven below cover research, technical checks and outreach, and the last section shows how they fit together on a single task.

How we picked these seven

Free SEO extensions age badly. A good number of the ones recommended in older roundups now open to an empty panel, ask for a paid seat, or stopped working altogether when Chrome retired Manifest V2 extensions. Everything on this list had to clear the same four tests:

• Still maintained. It has been updated recently and runs in a current Manifest V3 Chrome, or in a Chromium-based browser such as Edge, Brave or Opera. Several also ship a Firefox build.
• Genuinely usable for free. The free tier answers a real question on its own, even if the deeper reports sit behind a subscription.
• One clear job. A toolbar that tries to do everything gets ignored. Each of these does one thing you would otherwise open a tab for.
• Honest about its data. The tool makes it reasonably clear whether a number is measured, modelled or estimated, so you know how much weight to put on it.

SEOquake

SEOquake is a great extension that every marketer should have in his browser. You can check live stats and the health of a certain webpage/website with a simple click, without opening any extra pages. The extension has accurate data about the number of pages indexed in Google and Bing, plus the site’s Semrush rank. The old Alexa column is gone for good, by the way: Alexa Internet was retired in May 2022, so any guide still telling you to “check the Alexa rank” was written for a different decade.

The extension also shows useful data about the latest index date, the website’s age, number of backlinks, and the opportunity of accessing the page’s Wayback Archive instantly. This data can be useful when researching sites for link building purposes if you can’t do a bulk search.

When doing a Google search, the tool also numbers all of the web pages for easier tracking and showcases the same live data mentioned above underneath each result. You can also sort the page based on SEO metrics like rank, index, and backlinks, as well as country and language. Furthermore, all results can be exported in a CSV format for offline work.

Two habits make SEOquake far more useful than the default install. First, open its preferences and switch off every parameter you never act on. A SERP overlay showing four numbers you trust is quicker to read and much faster to load than one showing fourteen you don’t. Second, treat the CSV export as the start of a prospect sheet rather than a curiosity: run your query, export the page, repeat for the next few pages of results, then dedupe by domain in a spreadsheet. Google is far less generous with long result pages than it used to be, so plan on exporting several standard pages instead of one oversized one.

One caveat worth knowing: the Wayback shortcut is the most underrated button in the whole panel. If a domain’s archive shows a casino directory in 2019 and a “lifestyle blog” today, you have learned more in five seconds than most authority metrics will tell you in an hour.

Ahrefs SEO Toolbar

Ahrefs’ SEO Toolbar can provide some highly important live data about websites without having to access the classic tool. When activated, the tool has two sections with information about the current webpage and the root domain. It shows on-page SEO data, broken link checker, and keyword metrics for URLs.

When the toolbar is fully active, it might look a bit distracting so you should put it on pause when not doing SEO work. But, even when on pause, the tool shows the DR of the root domain you’re visiting in the right corner. If you like Ahrefs and the metrics they are using, the tool is a great option for SEO work on the run.

The part we use most has nothing to do with authority scores. The on-page report reads the page the way a crawler does and lays out the title, meta description, canonical, meta robots directives, hreflang annotations, heading structure, word count and Open Graph tags in one panel. That is enough to catch the three failures that quietly kill pages: a canonical pointing somewhere unintended, a stray noindex left over from staging, and an H1 that doesn’t match what the page is actually about. The redirect tracer sits next to it and shows the full hop chain with status codes, which is exactly what you want before accepting a link that arrives via two 301s and a 302.

Be aware that the split between free and paid features has moved more than once. The on-page report, header and redirect inspection and broken-link checking have stayed free; richer link and keyword metrics generally need an Ahrefs plan. Check what your account currently unlocks before you build a process around a number. If you want the reasoning behind the score itself, Ahrefs explains how Domain Rating is calculated from the link graph.

MozBar

When it comes to SEO metrics, there are two general types of people, those that use the Moz Domain Authority (DA), and those that use Ahrefs’ Domain Rating (DR). Both of the calculate pretty much the same thing but in slightly different ways. The MozBar allows you to directly check out the Domain and Page Authority of a site, as well as its Spam Score.

This is essential data that can give you a better understanding of a site, especially if you have any business with the said site. The tool can also give you data about on-page issues, and allow you to extract the SERPs, among many other things.

Two things are worth spelling out. MozBar needs a free Moz account before it shows anything, which trips people up on a fresh install. And neither DA nor DR is a Google metric: both are third-party models of a link graph, expressed on a compressed scale where moving from 20 to 30 is far easier than moving from 60 to 70. Use them the way a recruiter uses a CV — to sort a pile, never to make the final call. Spam Score works the same way. It is a risk model built from patterns Moz associates with low-quality sites, not proof that a domain has been penalised, and a slightly elevated score on an otherwise excellent niche publisher is not a reason to walk away.

Where MozBar earns its place is Page Authority. Domain-level scores flatten everything; a strong domain can still host a page nobody links to. If you are pitching a resource inclusion, PA on the target page tells you far more about whether that link will do anything for you.

Google Lighthouse

If you like free tools, then you’re probably very familiar with Google PageSpeed Insights. It is a free tool that lets you check a site’s performance, load speed, mobile behaviour, and other on-page SEO information. What confuses most people is that the report stacks two completely different kinds of data on top of each other. The upper block is field data from the Chrome User Experience Report: real Chrome visitors, real devices and connections, aggregated over the previous 28 days. The block below it is lab data produced by Lighthouse: one simulated load, on a throttled mid-range mobile profile, from a Google data centre. Field data tells you what your visitors actually experienced. Lab data tells you why, and because it is reproducible it is the one you test a fix against.

Google Lighthouse offers a more in-depth analysis than PageSpeed Insights alone, because it scores four separate categories — Performance, Accessibility, Best Practices and SEO — and each audit comes with the specific elements that failed. The three Core Web Vitals are Largest Contentful Paint, Interaction to Next Paint and Cumulative Layout Shift — though a lab run can only measure LCP and CLS directly, and reports Total Blocking Time as its stand-in for responsiveness, which is why INP appears in the field section of PageSpeed Insights rather than in the Lighthouse report. If you learned this list a few years ago, note that INP replaced First Input Delay in March 2024, so any checklist still chasing FID is measuring something Google no longer uses.

Run it properly and the numbers stop bouncing around:

1. Open the page in a new Incognito window so cookies, logged-in states and your other extensions stay out of the way.
2. Open DevTools, go to the Lighthouse panel, and choose the Mobile device profile — that is what Google indexes with.
3. Select the categories you actually need. Running only Performance is much faster when you are iterating on a fix.
4. Run the audit three times and take the middle result. A single run on a busy machine is noise.
5. Fix one thing, re-run, and record the delta. If the score moved but the field data in PageSpeed Insights doesn’t follow within a few weeks, you optimised the lab, not the visitor.

The Performance number is the one everyone screenshots, but the Accessibility and SEO categories are the cheapest wins on most sites: missing alt text, unlabelled form fields, links with no discernible text, a missing meta description. Google’s own SEO starter guide covers the same ground if you want the reasoning rather than the checklist.

SimilarWeb

SimilarWeb has both an online tool but also an extension that can give you useful data about your site’s traffic, rankings, and traffic sources as well as different other stats related to the site. It’s a great tool if you want to quickly evaluate competitors and find some link opportunities.

Read those numbers as modelled estimates, not measurements. SimilarWeb does not have analytics access to the sites it reports on; it infers volume from sampled behavioural data, and the smaller the site, the wider the error bars. For a domain with a handful of thousands of visits a month, the absolute figure can be badly wrong. What stays useful even then is the shape of the traffic: the split between search, direct, referral, social and paid.

That shape is a fast quality filter for link prospecting. A publisher with a healthy search share and a spread of referring sources is a real site with a real audience. A “media outlet” whose traffic is almost entirely direct, with a country mix that has nothing to do with its language, is usually a link farm wearing a nice theme. You do not need the number to be accurate for that comparison to hold.

Hunter

Hunter.io is one of the best tools when it comes to finding a website’s email address. Some sites have their email address hidden well or not even listed at all. Hunter can help you find a valid email, with a probability score as well as the person’s name, job title, and even phone number if it’s a personal email address.

Hunter also has an extension besides their web tool that can offer the same results but in a more efficient manner. The free plan includes a monthly allowance of searches and verifications — the exact number has been revised several times over the years, so check the current plan page rather than trusting an old blog post. Historically, a search that returns nothing has not consumed an allowance, which makes speculative lookups cheap. The tool can be great if you need to do some casual SEO or link building work.

Use the confidence score as a routing rule rather than a yes/no. Anything high-confidence and role-based can go straight into your sequence. Anything low-confidence should be verified first, because bouncing cold mail is the fastest way to damage the sending reputation of a domain you spent years building. And if the extension only offers you a generic pattern guess, spend two minutes on the site’s about or contributors page instead — a named editor answers far more often than a shared inbox.

Two rules we hold ourselves to when prospecting in Europe. Contact people in their professional capacity about something plausibly relevant to their job, and make it trivial to tell you to stop — an honest one-line opt-out at the bottom of the first message, honoured immediately. A tool that finds an address does not decide whether you should use it.

Keyword Surfer

Doing keyword research and getting valuable data with a paid tool can be pretty easy. However, it is quite difficult to find a free tool that can be great for keyword research, give you suggestions, as well as traffic data. Keyword Surfer can suggest related keywords for any search query with global and local volumes across the countries it supports, right inside the Google results page. The tool also shows word counts and estimated traffic for the ranking pages, so you can see at a glance whether a query is being won by 600-word answers or by 3,000-word guides.

A quick way to turn that overlay into a brief: search your target term, note the word count band the top five results cluster around, open the related-keywords panel and pull every suggestion with meaningful volume that a reader would expect the page to answer, then group those suggestions into the sections of your outline. You are not trying to sprinkle them into the text — you are checking that your structure covers the same questions the winning pages cover, plus at least one they don’t.

Treat free volume figures as order-of-magnitude signals. Modelled estimates disagree with each other constantly, and none of them see what Search Console shows you about your own site. Use them to rank ideas against each other, then let impressions data decide what to expand.

The seven at a glance

Extension	Best for	Free tier gives you	Watch out for
SEOquake	Fast SERP triage	SERP overlay, index counts, site age, CSV export	Default view shows more parameters than anyone reads
Ahrefs SEO Toolbar	On-page and redirect checks	Title, canonical, robots, hreflang, headings, redirect chain	Link and keyword metrics depend on your plan
MozBar	Comparing candidate domains	DA, PA, Spam Score, SERP export	Needs a free Moz account; scores are models, not Google data
Google Lighthouse	Technical and performance audits	Performance, Accessibility, Best Practices, SEO audits	Lab data only — pair it with field data before you celebrate
SimilarWeb	Sanity-checking a publisher	Traffic estimate, channel mix, country split	Estimates get unreliable on small sites
Hunter	Outreach contact discovery	Monthly allowance of searches and verifications	Verify low-confidence addresses before sending
Keyword Surfer	Research inside the SERP	Volume estimates, related terms, word counts	Modelled volumes; confirm against Search Console

A 15-minute workflow: vetting a link prospect with free tools only

Here is how these seven fit together on a real task — deciding whether a site that just pitched you a “collaboration” is worth answering.

1. Open the homepage and read the MozBar bar. Note DA, PA and Spam Score. This is a sorting step only; nothing is decided yet.
2. Check the archive. Use SEOquake’s Wayback shortcut. A domain that changed language, topic or owner in the last two years needs a much better explanation than a high DA.
3. Look at the traffic shape in SimilarWeb. Is there a real search share? Does the country mix match the site’s language and stated audience?
4. Count the indexed pages in SEOquake. Thousands of indexed pages against a tiny content archive usually means auto-generated pages or an open subdomain.
5. Open the page they want to place the link on. Run the Ahrefs on-page report: check for noindex, check the canonical, and see whether the section is linked from anywhere in the site’s own navigation. Orphaned “partners” directories are worthless.
6. Read the outbound pattern. If every recent article carries three links to unrelated commercial sites in unrelated languages, you are looking at a link shop.
7. Only if all of that passes, find the editor in Hunter and write a specific, non-templated first message referencing something they actually published.

The failure pattern is consistent enough to be worth naming. A respectable domain score sits on top of an archive that shows a completely different site, often in a different language, two or three years ago; the traffic mix is almost entirely direct; and the index count is far larger than the visible content archive. No single one of those is proof of anything. Together they describe an expired domain rebuilt to sell links, and every step of that check runs on the free tools above.

Keep your toolbar fast, private and honest

• Read the permissions. Most SEO extensions legitimately need to read the page you are on. “Read and change all your data on all websites” on an extension that only formats text is a different story.
• Use a separate browser profile for SEO work. Extensions stay out of your personal browsing, and you avoid personalised results skewing what you see in the SERP.
• Pause what you are not using. Several toolbars fire API calls on every page load. Beyond the privacy angle, that is latency you are adding to your own browsing.
• Never benchmark performance with extensions running. They inject scripts and inflate the very metrics you are trying to measure. Incognito, or Lighthouse’s clean profile, every time.
• Re-check your stack once a year. The Manifest V3 transition quietly killed a batch of older extensions, and an extension that silently stopped updating its data is worse than no extension at all.

Frequently asked questions

Can I really run SEO on free tools only?

For a single site, largely yes. Search Console gives you your own query, page and indexing data for free, Lighthouse covers technical auditing, and the extensions above cover competitor triage. What you cannot get for free is scale: bulk backlink exports, historical rank tracking across hundreds of keywords, and reliable third-party volume data. That is precisely what agencies pay for.

Do I need all seven installed at once?

No, and you probably shouldn’t. Install SEOquake or MozBar (not both — they overlay the same SERP), the Ahrefs toolbar for on-page checks, and Hunter only during outreach weeks. Lighthouse is built into Chrome DevTools, so it costs you nothing to keep.

Does Google use Domain Authority or Domain Rating?

No. Both are third-party scores built by SEO vendors from their own crawls of the web. They are useful for comparing candidates against each other, but Google has never published or endorsed a single site-wide authority number, and no threshold in either tool guarantees anything.

Why do two extensions report different numbers for the same site?

Because they are looking at different indexes. Each vendor runs its own crawler, discovers a different subset of links, and applies its own model on top. Disagreement between tools is normal and expected — what matters is that you compare prospects within one tool, not across several.

Do these extensions work outside Chrome?

Most work in any Chromium-based browser — Edge, Brave, Opera, Vivaldi — because they share the same extension format. Firefox support varies by vendor. Lighthouse is a special case: it is built into Chrome DevTools and also available as a standalone command-line tool.

Conclusion

SEO professionals that have a large budget prefer to go for paid tools to save time and get quality results instantly without any hassle. But, if you’re a beginner SEO, you might want to maximize your budget and take advantage of free tools to get a similar result. Browser extensions can be pretty great since they allow you to save a lot of time by getting instant data for a certain site.

The seven free browser extensions for SEO that we mentioned above can be highly useful, regardless if you’re a beginner or pro. You can use them for technical SEO, keyword research, link building or just to get a better idea about your competitors.

The judgement, though, is still yours. These tools shorten the distance between a question and an answer; they do not decide which questions are worth asking, and they cannot tell you whether a link is worth having. Install the two or three that match the work in front of you this month, learn what their numbers actually measure, and treat every score as a hypothesis you confirm with your own data.