Companies Using Swagger UI

I expected Swagger UI to be a simple count: an open-source API viewer, found wherever it renders. Our October 2026 crawl finds it on 3,094 domains, and 1,693 of them match a company. Getting to that number took a correction. A domain counts when its front page loads Swagger UI's script, defines the SwaggerUIBundle object, or carries a stylesheet with Swagger UI's class names, and that last test caught products that only style Swagger UI. We removed 375 of them. Swagger UI itself is free under the Apache 2.0 licence, so none of this is a count of paying customers.

What the count measures

On 30 random live domains, 29 pages loaded. Six drew Swagger UI on the page, three of them still titled just "Swagger UI". Nine loaded its script or its full stylesheet without drawing docs there, usually because the app bundles it for an API page elsewhere. Three carried a few Swagger UI style rules of their own. The other eight carried only another product's styling (the Docsy theme for Hugo, Scroll Viewport or ChurchTools), and across all live domains those three products came to 375 sites, which we removed. Of what's left, 715 domains name a Swagger UI file or container in the page HTML itself.

Sales signal: for a high-confidence list, start with hostnames that look like API documentation. On the cleaned set, api (270 domains) and docs (252) are the two most common hostname prefixes, and developer adds 100.

A baseline, not yet a trend

The chart has a single point, the cleaned October 2026 figure of 3,094, so it can't show growth yet. What we can see is turnover. Since March 2026, 547 domains have dropped Swagger UI on at least one hostname, and 27 of them still run it on another.

"Swagger UI's footprint is wider than its usage. Hundreds of sites carry its class names because a theme or widget styles it, so the honest count starts with the pages that load its code." - Mehmet Suleyman, CEO & Co-founder at TechnologyChecker.io

Sales signal: treat this as a pool of about 3,100 API-publishing organisations and prospect it for what it tells you about a company (it publishes an API), not for momentum.

Who publishes with it

36.49% of matched companies with a known size have 1 to 10 employees and 31.23% have 11 to 50. The base is young: 68.35% were founded in 2010 or later. The 126 companies above 1,000 staff are where the named portals sit. DHL runs its API developer portal on it, and so do Amadeus, Lumen, OpenText, Equifax, Trellix, Condor and Starling Bank. FIS uses it inside Code Connect, its API marketplace, and Red Hat on Partner Connect. Some public bodies render it directly: the FDIC's BankFind API documentation and SEPTA's API page both draw Swagger UI on the page we checked.

Sales signal: at a large company, a Swagger UI detection usually points to the team that owns the developer portal or API program. That team buys API gateways, portal software and documentation tools.

Industry and geography

Software Development (21.38%), IT Services (9.48%) and Technology, Information and Internet (9.05%) lead, and with IT & Services and security the tech cluster reaches 43.81%. Financial Services (6.82%) and Government Administration (3.04%) follow, and both show up in our list as API and open-data portals. The United States leads with 466 matched companies, but Europe is close behind: France (105), the United Kingdom (102), Germany (90), Spain (72), the Netherlands (70) and Denmark (62) add up to 501. Several of the European rows in our company list are open-data portals and university systems that come with Swagger UI built in.

Sales signal: in Europe, check whether a row is a platform portal (Opendatasoft, CAMPUSonline) before you pitch, because there the vendor picked Swagger UI, not the site owner. Many of the large US rows are a company's own developer portal, such as Equifax's or Lumen's.

Docs generators: beside, not instead

No switching flow passed our tests, so this page has no migration table. Most sites with both tools keep both. Of 91 domains ever seen with Docusaurus and Swagger UI, 81 run both today. GitBook and Postman API Documentation each share 39 live domains with it, and MkDocs 26. A static docs site often embeds Swagger UI for its API reference page, so the two tend to appear together.

"Since March, seven domains that dropped Swagger UI run Docusaurus, while 81 run both. Most teams add a docs site and keep Swagger UI for the API reference inside it." - Mehmet Suleyman, CEO & Co-founder at TechnologyChecker.io

Sales signal: vendors of hosted API reference tools should pitch Swagger UI sites on what they add to the reference page (search, versioning, an API client), not on replacing the docs platform around it.

The stack around it

Percentages here are of the 3,094 live Swagger UI domains. Next.js runs on 25.18%, React on 18.1%, Vue.js on 11.12% and Angular on 10.63%. Amazon Web Services hosts 24.01% and Vercel 7.11%. On the server side, ASP.NET is on 8.99%, Ruby on Rails on 5.69% and Express on 4.82%. The ASP.NET share matters because Swashbuckle, the ASP.NET Core package whose README describes an embedded version of swagger-ui, was the default in Microsoft's web API template until the .NET 9 release removed it.

Sales signal: AWS-hosted API teams on modern JavaScript front ends are the core of this list. .NET shops on newer templates no longer get Swagger UI by default, which opens a door for documentation tools that fill the gap.

Releases, licence and naming

The GitHub repository dates from 2011, carries the Apache 2.0 licence and shipped v5.33.2 on 12 October 2026. SmartBear publishes it on npm as swagger-ui, swagger-ui-dist and swagger-ui-react. The specification it renders is now called OpenAPI; the OpenAPI Initiative says it was based on the Swagger Specification donated by SmartBear. FastAPI still ships Swagger UI and ReDoc as its two default docs pages, and 238 domains in our crawl have a front page titled just "Swagger UI".

Sales signal: a default-titled Swagger UI page on a public host is an API whose team hasn't customised its docs page. For portal and API-security vendors, that's a concrete opening line.

Key takeaways

1. 3,094 live domains after removing 375 theme and widget sites, #9 in Documentation & Knowledge Base with 1.66%.

2. Only 6 of 29 sampled front pages drew Swagger UI docs; 9 more load it in an app bundle without drawing it there.

3. API developer portals at DHL, Amadeus, Equifax and Starling Bank are the clearest enterprise users.

4. Six European countries (501 companies) outnumber the United States (466).

5. Docs generators run beside Swagger UI: 81 of 91 Docusaurus overlaps still run both.

How to use this list

Filter by industry and by hostnames such as api, docs and developer, then check whether a row is a platform portal. For the full list of 3,094 Swagger UI domains with company, size and stack data, explore TechnologyChecker.io. Our guide to technology detection methods explains why a stylesheet test reaches further than a script test.