Companies Using Fly.io

I opened Fly.io's October 2026 numbers expecting a developer platform's footprint, small software companies and a few funded start-ups. That's in there, but it isn't the first thing you see. A domain counts here when its page response comes through Fly.io's edge proxy, shown by a fly-request-id header, a Server: Fly or Via: fly.io line, or Fly's cookie. It's a server-side signal, hard to fake and hard to miss. That gives 10,221 live domains, 4,594 of them matched to a company, and 16th place of 44 in PaaS.

Four platforms inside the count

The biggest single group isn't a developer at all. 2,815 of the 10,397 domains live when we checked in October (27.1%) also run Ahoy, a Rails analytics library, and almost all of them are artists' shops on Art Storefronts. I loaded five whose pages are titled "Shop Art": all five answered through Fly.io and carried an Art Storefronts "powered by" note in the source. Then I took 30 random domains from the group whose titles don't start with "Shop". 20 carried the same note, 3 redirected to Art Storefronts' suspended-site page, 2 were unrelated Rails apps, and 5 didn't load or had moved elsewhere.

Three smaller platforms do the same thing. The Church Co's church sites are on 730 Fly.io domains and Raisely's donation pages on 546; I opened five of each, and every one answered through Fly.io. And 167 of the 184 accounting firms in our matched data run an identical client portal from Double, a close-management app for bookkeeping firms, on subdomains such as clients.bookkeepandprosper.com.

Sales signal: split a Fly.io list before you prospect it. An artist with an Art Storefronts shop or a charity with a Raisely page didn't choose Fly.io and won't talk to you about hosting. The platform did, and that's one account, not hundreds.

Growth since June

The chart reads 7,161 domains in June, 8,053 in July, 8,961 in August, 9,903 in September and 10,221 in October, a gain of 3,060 in four months. Two things on our side feed that line: the set of domains we crawl turns over every month, with dead sites dropping out and new ones coming in, and our detection signals widen over time. So I read the shape more than the slope. Monthly gains ran at about 900 for three months, then fell to 318 in October.

"More than a quarter of Fly.io's sites belong to one artist-website company's customers. The developer platform story is real, but you have to take the platforms out to see it." - Elif Arslan, CMO & Co-founder at TechnologyChecker.io

Sales signal: Fly.io is growing in our crawl, but one platform moving its customers in or out could swing the total by thousands. Watch the platform accounts as closely as the headline.

Who the companies are

75.62% of matched companies with a known size have 1 to 10 employees and 17.76% have 11 to 50. Age points the same way: 40.68% were founded in the 2020s and 35.87% in the 2010s. Only 29 companies have more than 1,000 staff, and those usually run one property on Fly.io: Mall of America's podcast site, Universal Robots' virtual expo, Tourlane's help centre. A few go further. Sleep Number's main site and Aramark Refreshments' site both answered through Fly.io when I loaded them, and so did DreamHost's homepage, so a web host runs its own front door through someone else's platform.

Sales signal: the core Fly.io buyer is a founder or a small engineering team. At the large names, look for the team behind the one app on Fly.io. It's rarely central IT.

Australia's charity cluster

The United States leads with 2,013 matched companies. Australia is second with 369, ahead of the United Kingdom (254) and Canada (170), and that's Raisely's doing: 201 of the 369 Australian companies run a Raisely donation page on Fly.io, as do 49 of New Zealand's 79. The industry chart carries the same fingerprints. 233 of the 242 religious institutions run The Church Co or Raisely sites, 154 of the 181 non-profits do too, and 84 of the 95 photography businesses are Art Storefronts customers. Software Development (9.09%) and Technology, Information and Internet (6.91%) are the top industries that look like Fly.io's own audience.

Sales signal: for fundraising, donor-data or charity CRM vendors, the Raisely rows of this list are a ready-made prospect set. Each one is a charity that already runs online appeals, and most are in Australia or New Zealand.

Overlap, not switching

Our switching tests found nothing to publish. 706 domains run Fly.io and Amazon Web Services today, 271 run Fly.io and Vercel, 90 Netlify, 14 Cloudflare Workers and 8 Render. For every pair, either most domains ever seen with both still run both, or the flows ran about evenly in each direction, so I can't call any of it migration. Churn is modest too. 731 domains have dropped Fly.io since we began tracking it on 16 March 2026, and some of those drops are partial: when I rechecked, 76 of the 738 domains on that list by then still ran Fly.io on another hostname.

"Fly.io sits beside Vercel and AWS on hundreds of sites. I don't see teams leaving one for the other. I see them using both." - Elif Arslan, CMO & Co-founder at TechnologyChecker.io

Sales signal: pitching a Fly.io customer on replacing Fly.io is a hard sell with nothing in our data behind it. Pitch what runs beside it instead, such as monitoring or a CDN.

The stack around it

Ruby on Rails is on 27.59% of live Fly.io domains, Ahoy on 27.1% and New Relic on 27.05%, and those three rise together because of the Art Storefronts sites. Set them aside and the frameworks look like developers' own apps: Next.js on 12.58%, React Router 9.42%, Phoenix LiveView 4.38%, Express 3.52% and Remix 2.54%. Phoenix LiveView is an Elixir framework, so that 4.38% is a group of Elixir teams worth knowing about. Sentry is on 11.44%, Cloudflare on 31.7% and jsDelivr on 33.5%.

Sales signal: error-tracking and APM vendors have room here. Sentry's 11.44% and Datadog's 0.6% leave plenty of Fly.io apps without a monitoring tag we can see from outside.

What it costs

Fly.io's pricing page (checked 11 October 2026) bills compute by the second. The smallest preset, shared-cpu-1x with 256MB, costs $0.0030 an hour or $2.19 a month. Volumes cost $0.15 per GB a month and egress $0.02 per GB in North America and Europe. New organisations get no free tier, only a trial capped at 2 hours of Machine runtime or 7 days, per Fly.io's pricing docs. Paid support runs from $29 a month to Enterprise from $2,500.

Sales signal: usage billing means a Fly.io customer's bill grows with traffic, so cost-monitoring tools have an opening once an app scales.

Key takeaways

1. 10,221 live domains, 16th of 44 in PaaS and 1,472 domains ahead of Render.

2. About a quarter of the footprint is Art Storefronts, and The Church Co, Raisely and Double add hundreds more platform-hosted sites.

3. A young, small base: 75.62% at 1 to 10 employees and 40.68% founded in the 2020s.

4. Heavy overlap with AWS (706 domains) and Vercel (271), and no switching corridor that passes our tests.

5. Growth every month since June, slowing to 318 domains in October.

How to use this list

Take out the platform-hosted sites first, then filter by size and country. For the full list of 10,221 Fly.io domains with company, size and stack data, explore TechnologyChecker.io. If you're comparing hosts, our Ruby on Rails profile covers the framework behind most of the Art Storefronts sites, and the Render and Heroku profiles cover Fly.io's closest rivals.