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,, 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 S10


YC W15

280 North

YC W08


YC W14


YC W12

YC W10


YC W13

YC S13

YC S17

80000 Hours

YC S15


YC S12

YC W08


YC W14

YC W16

YC W16


YC W11


YC S10

YC S12


YC S09


YC S17

YC W17


YC S10


YC W18

YC W18


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

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.

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.

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 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

Dropbox is a file sharing and productivity startup created by Drew Houston and Arash Ferdowsi in 2007.

Stripe is a financial technology company providing software that allows businesses and individuals to make and receive online payments.

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

Biotechnology microbial genomics company based in San Francisco

A platform that enables users to search for building contractors.

Driverless truck company based in San Francisco, California.

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

Airbnb provides an online platform for listing, searching and booking rental accommodations.

A mobile application allowing its users access their office, building or apartment

inDinero is a company developing software for tracking and managing for startups and small businesses.

DrChrono is a company providing EHR, Practice Management, and Revenue Cycle Management Solution APIs. It participated in the W11 cohort of Y Combinator.

Segment is a company providing a data infrastructure for businesses.

SendHub is a company providing an online messaging system for businesses.

An industrial biotech company developing a commercial bioprocess for manufacturing bio-based malonic acid.

A software company providing cloud-based employee management solutions. It combines human resources, information technology, and operations. It was founded in 2016 and has locations in San Francisco, California and Bangalore, India.

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Associated investment funds

Accelerator batches

Accelerator Batch
Accelerator batch companies

A listing of the companies in the W19 batch

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