We checked every Y Combinator domain. Nine are available.
By Domain Yoga · Last updated August 1, 2026
We checked all 6,063 domains belonging to Y Combinator companies — every batch, every status — and nine are available to register. That is 0.148%, or roughly one in every 674. Zero of the 3,714 .com domains are free. Not one, including the 705 .com domains belonging to companies YC itself lists as inactive, some from batches more than a decade old. If you have ever been told to hunt for lapsed startup domains and inherit their authority, this is what the supply side of that strategy looks like: nine free names, 102 parked at brokers with an asking price, and everything else still held by someone.
How many YC domains are actually available?
Nine, from a snapshot of 6,108 companies taken on 31 July 2026 via the open-source yc-oss mirror of YC’s official directory API. Of those, 6,063 had a domain we could extract — 38 list no website at all, and 7 list something unusable like a bare http://. Every one of the 6,063 was resolved.
| Company status | Domains | Available |
|---|---|---|
| Active | 4,211 | 0 |
| Inactive | 1,034 | 7 |
| Acquired | 795 | 2 |
| Public | 23 | 0 |
| Total | 6,063 | 9 |
Not a single active company’s domain is unregistered, which is unsurprising. The interesting number is the second row: even among companies YC marks as dead, 99.3% of the domains are still held by someone.
Here is the entire list of what is free, which is short enough to print in full:
skylights.aero · getpulse.care · vathys.ai · userhero.io · accept.inc · unfaze.ai · unsurvey.ai · get-coffee.ai · echothat.ai
Two more — afrostream.tv and blackoak.tv — look free to an automated checker and are not. More on those below, because they are the most instructive names in the dataset.
Why does the extension matter more than whether the company died?
Because holding a name is a recurring bill, and the size of that bill varies enormously by extension.
| Extension | Domains | Available | Rate |
|---|---|---|---|
.ai | 845 | 5 | 0.59% |
.io | 343 | 1 | 0.29% |
.com | 3,714 | 0 | 0.00% |
.co | 220 | 0 | 0.00% |
.dev | 114 | 0 | 0.00% |
.app | 93 | 0 | 0.00% |
| Everything else | 734 | 3 | 0.41% |
Five of the nine free domains are .ai — the most expensive extension in this table by a wide margin. It carries a mandatory two-year minimum and roughly $80–160 a year, against about ten dollars for a .com.
When a company folds, a .com has two safety nets and an .ai has neither. At ten dollars a year a .com is cheap enough to renew on reflex, long after anyone remembers why — and if it does lapse, drop-catchers are waiting to re-register anything pronounceable the moment it hits the zone. An .ai is expensive to keep out of sentiment and expensive to hold on speculation, so when the founder stops paying, often nobody else starts.
Split the dead companies by extension and the effect is stark:
- Inactive companies on
.com: 0 of 705 available - Inactive companies on everything else: 7 of 329 available
Death is necessary — every one of the nine belonged to a company that folded or was acquired — but nowhere near sufficient. A domain comes free only when the company dies and holding the name stops being worth the price to anyone at all, including the people who buy names for a living.
Are the available ones worth having?
We pulled backlink data on the three with meaningful authority, and the ranking inverts the moment you look past the headline number.
skylights.aero scores DR 54 — enormous next to a new site’s zero. But of its 135 live referring domains, Ahrefs’ own spam classification flags 106 of them, or 79%. Below three legitimate links sit zlutag.com, ylutag.com, aligow.com, zomatt.com, dotpim.com — six-letter nonsense domains clustered at DR 59–61. That is a private blog network, and the DR it produces is manufactured rather than earned.
accept.inc scores lower at DR 27 and is the genuinely valuable one: 77 non-spam referring domains including nytimes.com, businessinsider.com, techcrunch.com, businesswire.com, axios.com and cbinsights.com. That is real press coverage of a real mortgage startup.
Which is exactly the problem. Those journalists wrote about home-buying finance. Pointing that history at something unrelated is what Google’s spam policies call expired domain abuse: “where an expired domain name is purchased and repurposed primarily to manipulate search rankings by hosting content that provides little to no value to users.” The policy turns on intent and use rather than on the purchase itself — Google’s announcement says plainly that “it’s fine to use an old domain name for a new, original site that’s designed to serve people first.”
Google has also been consistent for a decade that the inherited-authority premise does not work in the first place. John Mueller’s position, stated repeatedly in Google’s webmaster office-hours, is that a domain left parked for years is treated as starting over, and that buying expired domains in the hope of a ranking bonus is not a strategy he would recommend.
So the honest read on our nine: one is a link farm, one is a good domain about the wrong subject, and the rest carry almost nothing. Registering them for SEO would be paying for a number in a tool.
What happened to the domains of the companies that died?
The active companies’ domains are doing what you would expect — running businesses. The instructive set is the dead ones. We checked all 1,025 registered domains belonging to inactive companies to see what “still registered” means in practice.
- 776 (75.7%) still point at a live address. Not necessarily a working site, but the name resolves somewhere.
- 102 (10.0%) are parked at a sales broker — Afternic holds 61, Atom 13, ParkingCrew 8, and BrandBucket, Sedo and ParkLogic 5 each, with the rest across smaller services. These have an asking price.
- 68 (6.6%) have no nameservers at all: registered, renewed, and pointed nowhere.
- 79 (7.7%) are delegated but serve no address.
So about one in nine dead-startup domains is obtainable — 9 free and 102 with a price, out of 1,034 — and the other eight would mean finding and persuading whoever holds them. If your name is taken, the options that actually work are mostly not this one.
How do you check 6,000 domains without getting it wrong?
This is worth a section because our first attempt was wrong, and the way it was wrong is the way most availability tools are wrong.
The obvious approach is to query rdap.org, a redirector that forwards to whichever registry owns the extension, and treat a 404 as “available”. It does not work. As of our checks in July 2026, rdap.org returns 404 for every .io and .co lookup regardless of registration — github.io and google.co both 404 there, while google.com redirects correctly. Any tool built that way reports registered domains as free, silently, and only for certain extensions.
What works is resolving the authoritative registry from IANA’s bootstrap file and asking it directly. Two extensions need help even then: .io and .co both run their own RDAP service but are absent from that bootstrap file, so a tool relying on it alone cannot see them at all.
Then there is the deeper problem: a missing registration record does not mean a name is registrable. Of eleven domains that RDAP reported as available, three were wrong. scout.ml returned a clean 404 and is registered. afrostream.tv and blackoak.tv returned clean 404s and are held by Tuvalu’s registry as reserved names — no record exists, and nobody can register them. Only WHOIS reveals either case.
So every “available” verdict here required agreement from two independent protocols: registry-direct RDAP, then registry WHOIS, then — for caj.al, on an extension that publishes neither — the .al zone itself, by distinguishing a name that does not exist from one that exists without nameservers. Coverage is 6,063 of 6,063.
The asymmetry is worth keeping if you check domains yourself: “taken” is safe to believe from one source, “available” is not. A registration record either exists or it does not, so nothing gets wrongly reported as taken. Every error runs the other way.
Three limits on all of this. The status labels are YC’s own, so a company marked inactive may have quietly continued. “Registered” says a record exists, not who holds it — several of these domains have plainly changed hands. And availability is a moment in time: these numbers describe 31 July 2026, and the only way to know about a name today is to check it today.
What should a founder take from this?
That the good names are gone, and waiting for them to come back is not a plan. Across two decades of the most-watched startup cohort in the world, one domain in 674 is free, and none of them is a .com. The name you want is not going to expire into your hands.
The useful response is volume plus verification, which is the only thing that makes a generator worth anything: describe your project to Domain Yoga and it returns around 250 availability-checked ideas ranked by brandability. Searches cost $2–$5 with no subscription, and credits never expire. It will not find you a name with the New York Times linking to it — nothing will, at registration price — but it will hand you a shortlist you can actually register, which the nine domains above are a fairly emphatic argument for.
If you want the companion study, we also looked at what YC founders actually name their companies — the words, the lengths, and why “AI” went from differentiator to background noise in about ten years.