Companies Using CentOS

What 32,041 servers are announcing

CentOS is not detected through anything clever. The server prints its own name in the Server response header, in a string like Apache/2.4.6 (CentOS), and we read it. That single line is why this profile is worth publishing. CentOS Linux 8 reached end of life on 31 December 2021 and CentOS Linux 7 on 30 June 2024, and 32,041 domains still announce the distribution in our August 2026 rollup.

The rest of the header tells you which one. Sampling live CentOS domains returns Apache/2.4.6 beside OpenSSL/1.0.2k-fips and either PHP/5.4.16 or PHP/7.3.33. That is the stock package set of a CentOS 7 install, and those packages stopped receiving backported fixes the day the distribution's support ended. Six of these domains were re-checked one at a time in September 2026: five still answered with the CentOS token, and the sixth had moved to Apache/2.4.58 (Ubuntu), which is exactly the churn the rest of this page measures.

The oldest customer base in the category

Put the age distribution next to Ubuntu, measured the same way on the same crawl, and the two barely overlap. 7.68% of matched CentOS companies were founded in the 2020s, against 22.16% on Ubuntu. Go the other way and it reverses: 14.96% of the CentOS base pre-dates 1980 against Ubuntu's 8.57%, and 62.51% of these organisations pre-date 2010 altogether. The 2000s band alone, 24.09%, is larger than everything founded since 2020 by more than three to one.

The named list carries the same signature. Seven of the 34 organisations below were founded before 1900 and 13 before 1950: Unito Media at the University of Turin, dated 1404 in the record, Shapoorji Pallonji (1865), Universidad Nacional de Colombia (1867), Sciences Po (1871), Punjab University (1882), Dabur (1884) and Institut Pasteur (1888). Two were founded after 2015.

Software does not age. Institutions do, and their servers age with them. The clearest predictor of an unsupported operating system in our data is not the size of the organisation or the country it sits in. It is the year it was founded.

Universities and ministries, not startups

Two industry rows make the CentOS top ten and appear nowhere in Ubuntu's: Higher Education at 2.46% and Telecommunications at 2.4%. On Ubuntu those places belong to Financial Services and Advertising Services. The named companies show why. Eleven of the 34 are universities, and the rest of the public sector fills in around them: Peru's Ministry of Education on umc.minedu.gob.pe, an Argentine provincial education authority on cendie.abc.gob.ar, Telekom Malaysia on blog.tm.com.my. This is the constituency that adopted CentOS for the reason it existed: a free, binary-compatible rebuild of Red Hat Enterprise Linux, for organisations that wanted the platform without the contract.

Size data backs it up from the other end. The base is dominated by very small companies, 53.42% at ten employees or fewer, which is shared hosting. But 485 organisations here employ more than 1,000 people, 3.43% of the sized base against 1.95% on Ubuntu. CentOS has proportionally more institutional weight behind it than the category leader does, which is what happens when a platform stops taking on new customers and keeps its oldest ones.

Where the exits actually go

Only one destination survives our test. 283 domains dropped CentOS while running AlmaLinux, 96 of them in the last 30 days and 279 in the last 90. Of every domain that has ever carried both signals, only 19.1% still carries both, well under the 40% ceiling we require before calling an overlap a move, and the direction is lopsided at roughly 47 to 1. AlmaLinux is also the obvious landing place: CloudLinux started it in 2021, after CentOS Linux was discontinued, as a free rebuild of Red Hat Enterprise Linux, and the AlmaLinux OS Foundation runs it now.

Scale matters more than the ratio here. 283 domains is 7.72% of the 3,667 that have stopped disclosing CentOS since March 2026, and 0.88% of the current base. Where CentOS appears beside another distribution the usual explanation is an organisation running several operating systems at once, which is coexistence and not a switch, so those pairings are absent from the table above by design.

Everyone expects an end-of-life distribution to empty out. What our records show is 279 domains leaving for AlmaLinux in ninety days, 0.87% of the base, and 32,041 that stayed where they were.

What the rest of the stack says

Apache at 99.64% is not a finding about CentOS operators, it is the measurement showing through: the token we read lives inside Apache's version string, so a CentOS host behind Nginx or a CDN cannot appear here at all. OpenSSL at 78.67% arrives in the same line. Look in front of the server instead. jQuery is on 79.53% of these domains, jQuery Migrate on 24.35% and jQuery UI on 23.95%, with WordPress at 24.1%. jQuery Migrate exists to keep code written for jQuery 1.8 and earlier running on later releases. A quarter of these sites are carrying an explicit marker of front-end code about as old as the operating system serving it, which is what a site nobody has revisited looks like from the outside.

What this page does not measure

Every number here is a floor. A domain behind a CDN answers with the CDN's header, ServerTokens Prod removes the token as a matter of routine hardening, and machines that do not serve HTTP never appear. 22 of the 34 named detections sit on a subdomain rather than a main site, and the pattern in them is its own finding: www.library.ualberta.ca, journals.ug.edu.gh, research.ku.ac.ke, alumni.pu.edu.pk, intranet.udec.cl, a helpdesk at glpi.ints.org.br. Nobody rebuilds the journals host. The count also cannot tell you which release a machine runs, only which family it announces.

The three-point series at the top of the page has the same caveat attached. 27,320 in June, 31,430 in July and 32,041 in August is a coverage line, not an adoption curve: the domain set turns over every month and our coverage widened across the same window.

What to take from this

If you are one of the 32,041, the useful facts are that the header is public, the version strings beside it are public, and the measurable exit route is AlmaLinux. If you sell migration, support or hardening, the shape of this base is unusually legible: old institutions, secondary hosts, Apache everywhere, and a public sector tail across Latin America, South Asia and Africa. And if you just want to know whether CentOS is finished, the honest answer from our records is that it is unsupported and still very much running. TechnologyChecker.io will keep counting it until the header stops appearing.