Y Combinator S2021 Demo Day Domain Trends – 54% Use a .com

Last year, Y Combinator hosted one of its demo days in which chosen early-stage startups gather and take turns to pitch their company or product to an invite-only audience of around 1,500 investors and media.

Y Combinator, a startup incubator, hosts these events twice per year. The summer 2021 edition featured 377 companies. I have domain data for 374 of those companies, and below I’m going to highlight some trends and statistics from the domains of startups featured in the Y Combinator event.


Domain Extensions

There were 49 different domain extensions used by the exhibiting startups.

As you might expect, .com ruled the roost with 54% of companies using the extension. That’s followed by .io with 9.36% usage and .co with 6.95% usage.

Here’s the top 5:

  1. .com – 54.01%
  2. .io – 9.36%
  3. .co – 6.95%
  4. .ai – 5.08%
  5. .app – 2.41%

Usage of new domain extensions (ngTLD) in total accounted for just 8.02% of all names listed, with .app accounting for 30% of ngTLD usage.


Types of .com Domains Used

With .com taking a resounding lead as the top domain extension in this data set, it may make you wonder what kind of .com domains the startups are using. Typically, early-stage startups are less likely to spend much money on an aftermarket domain, which often leads to some creative domain registrations.

I’ve found that the most popular trend in these .com domains seems to be adding a prefix. In fact, 16% of companies using a .com are operating on a domain that either starts with: get, join, try, go, or use. Among those, get is the most popular prefix.

Brandable company names seem to be popular, too. The dataset includes company names such as Govly, Datlo, Preki, and Tantl, all using exact-match .com domains.



The average length for a domain name in this dataset is 8 characters. Given the necessity among .com domains to often add letters or words in order to register an available domain, it’s no surprise that the average length for a .com domain is 9 characters.

Here are the average lengths for the 5 most popular extensions:

  1. .com – 9 characters
  2. .io – 7.7 characters
  3. .co – 7.9 characters
  4. .ai – 6.2 characters
  5. .app – 7.1 characters


Notable Domains

Here are a few notable names that I spotted within this dataset:

  • Jupe.com – a “dwelling unit” creator
  • Front.page – a company called FrontPage using this hack
  • Beeper.com – acquired from Reflex Publishing as an upgrade from BeeperHQ.com. It likely cost a substantial amount


Data is directly from TechCrunch’s coverage.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.