SEO Used by UK Marketing Agency Companies: Market Share (2026)
Across 2,406 UK marketing agency companies with a detectable SEO system, Yoast SEO leads with 77.4% share, ahead of RankMath SEO at 12.5% and All in One SEO at 7.2%.
Among 55,557 trading UK marketing agency companies, 2,406 have a detectable SEO system. Yoast SEO is the clear majority choice, used by 1,863 companies and accounting for 77.4% of detected usage.
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RankMath SEO is the second-largest system at 12.5% (301 companies), followed by All in One SEO at 7.2% (174). SEOmatic, The SEO Framework and Google XML Sitemaps together make up the remaining long tail across 97 companies.
Yoast SEO leads across all three employee bands. Its share is 77.0% among agencies under 10 employees, 78.5% among those with 10–50 employees, and 77.0% among those over 50 employees.
2,399
marketing agency with detected SEO
Of 56,295 UK marketing agency
4.3%
Detection rate
2026
7
Systems detected
In this category
77.4%
Leader share
Yoast SEO
UK Marketing Agency SEO market share
Share of the 2,399 UK Marketing Agency with a detectable system. As of June 2026.
SEO compared
| System | UK Marketing Agency | Share | Median headcount | London share | Typical profile |
|---|---|---|---|---|---|
| Yoast SEO | 1,857 | 77.4% | 6 | 27.8% | Small agencies, broad usage |
| RankMath SEO | 297 | 12.4% | 7 | 27.6% | Small agencies, secondary option |
| All in One SEO | 172 | 7.2% | 6 | 27.3% | Small agencies, lower-share alternative |
| SEOmatic | 53 | 2.2% | 7 | 39.6% | Small agencies, London-skewed niche |
| The SEO Framework | 35 | 1.5% | — | — | View these companies in Firmbase → |
| Google XML Sitemaps | 9 | 0.4% | — | — | View these companies in Firmbase → |
| SEOPlatform.io | 7 | 0.3% | — | — | View these companies in Firmbase → |
Systems detected below the page threshold appear with counts only; their full lists are available in the Firmbase app.
Market leader by size
The leading SEO system shifts with company size: among UK Marketing Agency with under 10 employees, Yoast SEO leads at 77% of the 1,615 with a detectable system; among UK Marketing Agency with 10–50 employees, Yoast SEO leads at 78.2% of the 724 with a detectable system; and among UK Marketing Agency with over 50 employees, Yoast SEO leads at 78.3% of the 60 with a detectable system.
Under 10 employees
77% of band
This band covers 1,611 UK marketing agency companies with a visible SEO system. Yoast SEO leads with 77.0%, while RankMath SEO and All in One SEO form the main alternatives across the wider market.
10–50 employees
78.2% of band
The 10–50 employee band has 734 companies and looks much like the smaller-agency market. Yoast SEO leads with 78.5%, leaving the rest of usage spread across RankMath SEO, All in One SEO and smaller systems.
Over 50 employees
78.3% of band
Only 61 companies with a visible SEO system sit in the over-50 employee band. Yoast SEO still leads with 77.0%, so larger marketing agencies do not show much divergence from the smaller bands.
How SEO usage is detected
Company data
Detected companies are joined to UK Companies House records and XBRL accounts data. Revenue and headcount figures come from the most recent filed accounts; where the company has not filed, values are estimated using a model trained on filed history and peer benchmarks and are labelled as estimates.
Detection
Firmbase crawls the public website of actively-trading UK companies and fingerprints the technologies present: tracking scripts, embedded forms, chat widgets, CMS markers and similar signatures. A company is included in this list when one or more of the technology's signatures are found on its site; closely-related variants of the same product are grouped under one name. Detection covers what is visible on the public web — a company using the technology purely internally, with no website footprint, will not appear. Counts are therefore a conservative floor, not a ceiling.
Freshness
Websites are re-crawled on a rolling basis and the underlying company data is refreshed from Companies House continuously; filings appear within days of submission. The list and its statistics are regenerated when the detected cohort moves meaningfully. You can see the last-updated timestamp near the top of the page.
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Frequently asked questions
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