Data Driven: Just 49.8% of Y Combinator (Winter 2021) Companies Use .COM

Y Combinator is a startup accelerator that has been responsible for the early-stage investments in thousands of companies, many of which have gone on to become household names. Since 2005, Y Combinator has helped Stripe, Airbnb, DoorDash, Coinbase, Dropbox, Twitch, Reddit, and many more to develop into the valuable brands we know today.

Every year, Y Combinator chooses a couple of hundred more companies to invest in, through its Summer and Winter programs. Here, I’m going to take a look at some of the companies that Y Combinator picked for their Winter 2021 batch of investments, to see what type of domains are in use by those companies.

These companies tend to be relatively young startups with little or no funding behind them, so the domain choices will show what type of names, and which extensions, are popular among companies with low or no budget. I’m using data gathered from in this article, and I’ll be looking at a total of 251 domain names.



In total, there are 36 different domain extensions used among the 251 domain names on show. Those extensions range from the obvious .COM, .IO, and .AI to the newer extensions such as .SOLUTIONS, .CLOUD, and .SPACE.

As you might expect, .COM dominates the chart with 125 uses, although it’s surprising to see that .COM accounts for just 49.8% of uses. I think that’s lower than I’ve ever seen while reviewing data sets like this.

Firmly in second place, although quite some way behind .COM, is .IO. This breakout extension accounts for 30 uses, or 11.95% of domain names.

After that is .CO in third place accounting for 8.7%. Here is the top 5:

com 49.8%
io 11.95%
co 8.7%
ai 6.77%
in 3.58%


New Extensions

Among the new batch of extensions that have been released in the past several years such as .APP, .CLOUD, or .SOLUTIONS, there seems to be minimal usage. From my data, new domain extensions account for 7.97% of total usage – that’s combining all new extensions together.

For individual new extensions, .APP is the most popular, accounting for just 2.3% of all domains. Here are the top 5 most popular new domain extensions, with their percentage usage among all 251 domains:

app 2.39%
live 1.19%
cloud 0.79%
tech 0.79%
space 0.39%



As you might expect, a domain name isn’t typically important to a new startup. The product and establishing the company are far more important. So, you won’t be surprised by the lack of short .COM domains, or one-word .COM’s. In fact, the average length for a .COM domain is 9.24 characters, which is fairly long.

In comparison, .CO’s average length is 7, and .IO’s average length is 8. This would suggest that companies that want a shorter name, perhaps to exactly match their company name, are looking away from the crowded .COM marketplace towards alternative extensions in search of a shorter domain name.

Among all new domain extensions, for example, the average length is 6.45 characters. That dataset includes domains such as,, and The equivalent .COM domains would cost six- or seven-figures apiece.


Prefixes and Suffixes

Of those companies opting to stick with .COM, we see many using suffixes and prefixes. These companies using suffixes and prefixes have likely either acquired the names for a minimal amount, or hand registered them.

Among the suffixes, there are several examples of descriptive words being used. For example, autism tool provider Juniper uses, and PCOS treatment company Veera uses

As for prefixes, five companies use “Get” in a .COM domain, four use “Try” in a .COM domain, and three use “Use” in a .COM domain. Adding a prefix or a suffix is a simple, quick, and cheap way of owning a .COM domain for a company without spending too much time and money on it.


Notable Domains

Some notable domains that stood out among the dataset include:

  • – this domain sold for $31,000 in February 2020, brokered by Grit Brokerage.


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