.io domains and subdomains
The GetDomainLists release contains 916,095 registrable .io domains and 19,807,500 subdomains under them — names only, as historical observations, not a list of live websites.
The subdomain file has 21.6 .io names for each registrable .io domain in the domain file, against 3.4 across all top-level domains. This is a ratio of file rows, not a typical count for one site: many domains have no subdomains in the file. The most common tracked leftmost label is www (2,061,634 names, 10.4% of .io subdomains).
.io domain names
How the 916,095 registrable .io names are built (the label before the suffix):
| Label type | Domains | Share |
|---|---|---|
| Letters only | 828,309 | 90.4% |
| Letters and digits | 47,393 | 5.2% |
| Digits only | 4,550 | 0.5% |
| Hyphenated | 35,468 | 3.9% |
| Internationalized (xn--) | 375 | <0.1% |
Public suffixes under .io:
| Suffix | Domains | Share |
|---|---|---|
io | 916,093 | 100.0% |
gov.io | 2 | <0.1% |
.io subdomains
Depth counts the labels to the left of the registrable domain.
| Depth | Subdomains | Share |
|---|---|---|
| 1 (a.example.io) | 6,520,900 | 32.9% |
| 2 | 2,744,563 | 13.9% |
| 3 | 4,902,855 | 24.8% |
| 4 or more | 5,639,182 | 28.5% |
Tracked leftmost labels (name patterns, not confirmed services):
| Label | Subdomains | Share |
|---|---|---|
www | 2,061,634 | 10.4% |
whm | 752,472 | 3.8% |
api | 144,608 | 0.7% |
dev | 53,573 | 0.3% |
admin | 35,134 | 0.2% |
staging | 34,528 | 0.2% |
test | 23,376 | 0.1% |
mail | 21,050 | 0.1% |
Shared namespaces under .io in this release (row counts, not ownership or activity):
| Namespace | Subdomains | Share |
|---|---|---|
ngrok.io | 7,067 | <0.1% |
github.io | 15 | <0.1% |
Getting only .io
The release is sold as two complete files covering every TLD in it, not as per-TLD lists. To keep only .io, filter the files you download, for example:
zgrep -E '\.io$' getdomainlists-2026-09-28-domains.txt.gz > io-domains.txt zgrep -E '\.io$' getdomainlists-2026-09-28-subdomains.txt.gz > io-subdomains.txt
Try the format first with a free sample of 1,000 .io domains (plain text, no sign-up). Both full files are $9 once, with 30 days to download.
Limits
- Historical observations collected up to this release (updated 28 September 2026); not proof that a name is registered, resolves or hosts a website today.
- Coverage is incomplete and uneven; these counts describe this release, not the whole .io namespace.
- Names only: no owner, contact, hosting or registration-date data.