Y Combinator

Y Combinator

Y Combinator (also known as YC) is a US based seed accelerator, which was started in March 2005.

Y Combinator was started in 2005 by Paul Graham, Jessica Livingston, Trevor Blackwell and Robert Tappan Morris.

Y Combinator pioneered a new model for funding startups. Their major innovations include funding companies in batches, giving standardized terms, and having weekly dinners that culminate in a demo day to a group of investors. The firm was originally funding startups in Cambridge, MA for their summer batch before moving both summer and winter batches to Mountain View, CA.

Y Combinator’s motto is "Make Something People Want". The program aims to focus the founders on further developing their product, team, and market, as well as refining their business model, achieving product/market fit, and scaling the startup into a high growth business.


The program culminates at Demo Day. An event where startups present their business to a selected audience of investors. As of 2016, Y Combinator had invested in ~940 companies including Dropbox, Airbnb, Coinbase, Stripe, Reddit, Zenefits, BuildZoom, Instacart, Twitch.tv, Machine Zone, Weebly, Paribus, and Chinese startup Raven Tech. Non-profit organizations can also participate in the main YC program.


Y Combinator also operates Hacker News, a social link sharing site where users can submit and share news. The front page consists of 30 links at a time, sorted via an algorithm that takes into account upvotes from the community. According to SimilarWeb, the site receives over 20 million visits per month.

Portfolio companies


10 By 10

YC S17

YC W15

YC W08

YC W14

YC W12

YC W13

80000 Hours

YC S15

YC S12


YC W14

YC W11

YC S10

YC S09

YC S17

YC S10

YC W18

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June 26, 2020
Y Combinator adjusts standard deal terms for its Winter 2021 batch and beyond

The first would see the size of the standard deal for YC startups decline from $150,000 for 7% (roughly a $2.1 million post-money valuation) to $125,000 for the same equity (or roughly a $1.79 million post-money valuation).

Y Combinator is also imposing a ceiling on its pro rata investing rights. YC will only take pro rata up to 4% of a subsequent round's size, which is smaller than the 7% equity stake the accelerator typically takes. If Y Combinator holds less than a 4% stake in a company, it may exercise its pro rata right for the lesser percentage stake.

September 28, 2018
New Standard Deal - post-money SAFE

Y Combinator announced the change to the standard investment deal. YC increased their investment from $120K to $150K. The $150K investment for 7% will be made on a post-money cap SAFE (Simple Agreement for Future Equity).

April 22, 2014
The New Deal

Sam Altman announces a new standard YC investment of $120k for 7% equity in the company. This replaced the previous standard of $97k ($17K for 7% along with an $80k safe note converted at next raise.

April 22, 2014
Board of Overseers announced

Included are Brian Chesky, Adora Cheung, John Collison, Patrick Collison, Drew Houston, Jessica Livingston, David Rusenko, Emmett Shear, and Sam Altman. All board members are either former YC graduates or founders.

February 21, 2014
Sam Altman announced as next president of Y Combinator

Taking over for Paul Graham, who had lead Y Combinator for nine years, Sam Altman is announced as the next president of Y combinator.

September 1, 2010
Alexis Ohanian joins

Previously cofounder of Reddit, Alexis Ohanian joins Y Combinator as a partner and ambassador to the East.

March 16, 2009
Sequoia Capital leads $2m investment in Y Combinator managed fund

Sequoia Capital and angel investors Ron Conway, Paul Buchheit, and Aydin Senkut invest in a YC managed fund intended to increase the startups YC invests in.

January 1, 2009
Y Combinator moves to Silicon Valley year round

Previously, Y combinator had alternated between Cambridge, MA and Silicon Valley.

April 11, 2005
"Make Something People Want" motto adopted

The phrase described in Paul Graham's Be Good post is still used as the Y combinator motto.

March 11, 2005

Founded March 11, 2005, in Cambridge, MA by Paul Graham, Jessica Livingston, Robert Morris and Trevor Blackwell.

Funded Companies

Ginkgo Bioworks

Ginkgo Bioworks is a biotechnology company using machine learning techniques and lab automation to engineer microorganisms as a service.

Momentus is a YC Summer 2018 batch company developing the in-space rockets powered by water plasma engines and based in Santa Clara, CA

Coinbase is a digital asset exchange company headquartered in San Francisco, California. It operates exchanges of Bitcoin, Bitcoin Cash, Ethereum, and Litecoin.

Indee Labs focuses on the development of microfluidic vortex shedding for rapidly and efficiently transfecting human primary immune cells with negligible perturbation. The team is focused on developing its core technology for short turnaround chimeric antigen receptor T cell (CAR-T) development and manufacturing.

A microventure capital firm and syndicate in California that focuses on seed and early stage investments.

A telemedicine service company that delivers oral contraceptives and various testing kits to its customers. It was founded in 2015 and has headquarters in San Francisco, California.

OpenDoor is a San Francisco-based real estate technology company offering virtual and streamlined real estate buying and selling founded in 2014 by Keith Rabois, Eric Wu, JD Ross and Ian Wong.

Aesthetic is a creative automation tool for digital marketers

RethinkDB provides an open-source distributed NoSQL document-oriented database storing JSON documents and scaling data for applications.

A software company making a workplace email communication platform for remote and office work.

DoorDash is a food delivery company. It participated in the S13 cohort of Y Combinator.

U.S-based e-learning platform teaching coding, UX, and data science.

636 Results
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Launch date
Hacker News

Social news website

Bookface is a private community for Y Combinator founders.

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Associated investment funds

Investment Fund
Total offering (USD)
Total sold (USD)
Date signed
YC Continuity
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Accelerator batches

Accelerator Batch
Accelerator batch companies
Y Combinator W21 Batch

The Winter 2021 batch of companies that Y Combinator invested in.

The Winter 2020 batch of companies that Y Combinator invested in.

The Summer 2020 cohort of companies that Y Combinator invested in.

Batch of companies that participated in the Summer 2019 class of Y Combinator.

A listing of the companies in the W19 batch