YC S21 Startups
Every Y Combinator Summer 2021 company we currently index — part of the latest YC companies rollup.
About YC S21
The Y Combinator S21 batch (Summer 2021) brought 331 tech startups into our index. This page lists every S21 company we currently track, with logos, taglines, and links straight to their own sites — no paywalled middleman. Notable S21 companies include Exa, Stepful, Abatable, Abhi, and Abstra. Each profile surfaces team size, founding year, location, and open roles when their careers page is publicly scrapable. The S21 cohort skews toward Dev Tools, AI / ML, and Healthcare — common patterns we see in this batch. Recurring tags across these companies: SaaS, B2B, Fintech, AI, Artificial Intelligence. The directory's filter UI accepts any of them as a query. Geographically, the S21 batch we have leans toward San Francisco, New York City, and London, with the rest spread across remote-first teams and other hubs. 2 of these are currently flagged as trending based on momentum signals; and the listing refreshes whenever the scrape runs, so changes propagate without a manual edit.
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Similar startups outside YC S21
1 of 4 similar companies is hiring right now · most common: Engineering
Other YC batches
Frequently asked questions
What is the YC S21 batch?
S21 is the Y Combinator batch code for the Summer 2021 cohort. Companies joining a YC batch go through a 3-month program in California and demo their product at the end. techstartupslist.com indexes 331 tech startups from this batch.
How many companies are in YC S21?
Our index currently tracks 331 active tech startups from the YC S21 batch. New companies appear here automatically when our daily scraper finds them; companies that shut down are flagged inactive and hidden from listings.
Which companies graduated from YC S21?
Among the S21 companies indexed here: Exa, Stepful, and Abatable, and 328 more on this page. Click any profile for category, team size, founding year, and open roles.
Where can I find open jobs at YC S21 startups?
Open roles from indexed S21 companies appear on our /jobs page, aggregated alongside roles from other indexed startups. Each role links directly to the company's official application page.
How often is the YC S21 page updated?
Automated scrapers refresh this page daily. The last index update was 2026-09-02. Inactive companies fall out of the count automatically — we don't keep dead listings live.