Y Combinator, LLC (YC) is an American technology
startup accelerator
Startup accelerators, also known as seed accelerators, are fixed-term, cohort-based programs, that include mentorship and educational components, and (sometimes) culminate in a public pitch event or demo day. While traditional business incubato ...
and venture capital firm launched in March 2005 which has been used to launch more than 5,000 companies.
The accelerator program started in
Boston
Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...
and
Mountain View, expanded to
San Francisco
San Francisco, officially the City and County of San Francisco, is a commercial, Financial District, San Francisco, financial, and Culture of San Francisco, cultural center of Northern California. With a population of 827,526 residents as of ...
in 2019, and was entirely online during the
COVID-19 pandemic
The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...
. Companies started via Y Combinator include
Airbnb
Airbnb, Inc. ( , an abbreviation of its original name, "Air Bed and Breakfast") is an American company operating an online marketplace for short-and-long-term homestays, experiences and services in various countries and regions. It acts as a ...
,
Coinbase
Coinbase Global, Inc. is an American cryptocurrency exchange. It was founded in 2012 by Brian Armstrong and Fred Ehrsam. Coinbase has over 100 million users, and is the largest U.S. based cryptocurrency exchange as well as the world's bigge ...
,
Cruise,
DoorDash
DoorDash, Inc. is an American company operating online food ordering and food delivery. It trades under the symbol DASH. With a 56% market share, DoorDash is the largest food delivery platform in the United States. It also has a 60% market sha ...
,
Dropbox
Dropbox is a file hosting service operated by the American company Dropbox, Inc., headquartered in San Francisco, California, that offers cloud storage, file synchronization, personal cloud, and Client (computing), client software. Dropbox w ...
,
Instacart
Maplebear Inc., doing business as Instacart, is an American retail media and delivery company based in San Francisco that operates a grocery delivery and pick-up service in the United States and Canada accessible via a website and mobile app. ...
,
Reddit
Reddit ( ) is an American Proprietary software, proprietary social news news aggregator, aggregation and Internet forum, forum Social media, social media platform. Registered users (commonly referred to as "redditors") submit content to the ...
,
Stripe,
Scale AI
Scale AI, Inc. is an American data annotation company based in San Francisco, California. It provides data labeling and model evaluation services to develop applications for artificial intelligence.
The company’s research arm, the Safety, E ...
,
Deel,
Helion Energy
Helion Energy, Inc. is an American fusion research company, located in Everett, Washington. They are developing a magneto-inertial fusion technology to produce helium-3 and fusion power via aneutronic fusion, which could produce low-cost clean ...
, and
Twitch
Twitch may refer to:
Biology
* Muscle contraction
** Convulsion, rapid and repeated muscle contraction and relaxation
** Fasciculation, a small, local, involuntary muscle contraction
** Myoclonic twitch, a jerk usually caused by sudden muscle c ...
.
History
Founded in 2005 by
Paul Graham,
Jessica Livingston,
Robert Tappan Morris
Robert Tappan Morris (born November 8, 1965) is an American computer scientist and entrepreneur. He is best known for creating the Morris worm in 1988, considered the first computer worm on the Internet.
Morris was prosecuted for releasing th ...
, and
Trevor Blackwell
Trevor Blackwell (born 4 November 1969, in Canada) is a Canadian-American computer programmer, engineer, entrepreneur and roboticist based in England.
Blackwell is a developer of humanoid robots. Blackwell is the founder and former CEO of Anyb ...
, Y Combinator (YC) initiated operations with concurrent programs in
Cambridge, Massachusetts
Cambridge ( ) is a city in Middlesex County, Massachusetts, United States. It is a suburb in the Greater Boston metropolitan area, located directly across the Charles River from Boston. The city's population as of the 2020 United States census, ...
, and
Mountain View, California
Mountain View is a city in Santa Clara County, California, United States, part of the San Francisco Bay Area. Named for its views of the Santa Cruz Mountains, the population was 82,376 at the 2020 United States census, 2020 census.
Mountain V ...
. However, operational complexities arising from managing two programs prompted a consolidation in January 2009, resulting in the closing of the Cambridge program and the centralization of activities in Silicon Valley.
Although often overlooked in early accounts, Jessica Livingston played a pivotal role in shaping Y Combinator's culture and success. As co-founder, she was instrumental in the organization's day-to-day operations and, crucially, in selecting founders.
In 2009, Y Combinator secured a $2 million investment led by
Sequoia Capital
Sequoia Capital Operations, LLC is an American venture capital firm headquartered in Menlo Park, California, specializing in seed stage, early stage, and growth stage investments in private companies across technology sectors. the firm had appro ...
, enabling increased annual funding for around 60 companies. Sequoia further supported YC in 2010 through an $8.25 million funding round, bolstering the organization's capability to accommodate a growing number of startups. Concurrently, Kirsty Nathoo joined the team, initially as an accountant, and subsequently as the Chief Financial Officer (CFO) in 2012. In 2011,
Yuri Milner
Yuri Borisovich (Bentsionovich) Milner (, ; born 11 November 1961) is a Soviet-born Israeli entrepreneur, investor, physicist and scientist. He is a co-founder and former chairperson of internet company Mail.Ru Group (later VK), and a founder ...
and
SV Angel
SV Angel Management LLC (SVA) is an American venture capital firm based in San Francisco, California. The firm focuses on investments related to the AI, software and IT sectors.
Background
Until mid-2009, Ron Conway made most of his investme ...
offered every Y Combinator company a $150,000 convertible note investment. The amount put into each company was changed to $80,000 when Start Fund was renewed.

Advisory roles were assumed by
Harj Taggar and
Alexis Ohanian
Alexis Kerry Ohanian (; born April 24, 1983) is an American internet entrepreneur and investor. He is best known as the co-founder and former executive chairman of the social media site Reddit along with Steve Huffman and Aaron Swartz. He also ...
in 2010, and
Paul Buchheit
Paul T. Buchheit (born November 7, 1977) is an American computer engineer and entrepreneur who created the email service Gmail. He developed the original prototype of Google AdSense as part of his work on Gmail. He also suggested Google's former ...
and Taggar were named partners in November.
Michael Seibel joined Y Combinator as a part-time partner in January 2013 before becoming a full-time partner in 2014.
In September 2013, Y Combinator began funding nonprofit organizations that were accepted into the program after testing the concept with
Watsi.
Sam Altman
Samuel Harris Altman (born April 22, 1985) is an American technology entrepreneur, investor, and the chief executive officer of OpenAI since 2019 (he was Removal of Sam Altman from OpenAI, briefly dismissed and reinstated in November 2023). He ...
took part in Y Combinator's inaugural cohort in 2005 as a founder. In 2014, Paul Graham appointed him as President.
Altman introduced a revised equity offering of $150,000 for a 7% stake.
Global outreach became evident in 2016 as YC partners embarked on visits to 11 countries (
Nigeria
Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea in the Atlantic Ocean to the south. It covers an area of . With Demographics of Nigeria, ...
,
Denmark
Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...
,
Portugal
Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...
,
Sweden
Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
,
Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
,
Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
,
Argentina
Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
,
Chile
Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
,
Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
,
Israel
Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...
, and
India
India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
) to engage with founders and learn about international startup communities.
That summer, Altman returned to Y Combinator as a founder and worked on
OpenAI
OpenAI, Inc. is an American artificial intelligence (AI) organization founded in December 2015 and headquartered in San Francisco, California. It aims to develop "safe and beneficial" artificial general intelligence (AGI), which it defines ...
. Leadership responsibilities were delegated to
Ali Rowghani and Michael Seibel for YC Continuity and YC Core programs, respectively. Startup School, introduced in 2017, provided startups with online courses and personalized coaching. More than 1500 startups graduated from the program in its first year.
In 2018, Y Combinator announced a new batch of startup schools. After a
software
Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications.
The history of software is closely tied to the development of digital comput ...
glitch, all 15,000 startups that applied to the program were accepted, only to learn a few hours later that they had been rejected. In response to the ensuing outcry, Y Combinator accepted all 15,000 companies involved in the incident. The same year,
Qi Lu, a former CEO of
Bing
Bing most often refers to:
* Bing Crosby (1903–1977), American singer
* Microsoft Bing, a web search engine
Bing may also refer to:
Food and drink
* Bing (bread), a Chinese flatbread
* Bing (soft drink), a UK brand
* Bing cherry, a varie ...
and
Baidu
Baidu, Inc. ( ; ) is a Chinese multinational technology company specializing in Internet services and artificial intelligence. It holds a dominant position in China's search engine market (via Baidu Search), and provides a wide variety of o ...
, briefly assumed the role of CEO for YC China. In November, YC announced Lu's departure and their decision to not pursue a program in China. YC China later morphed into
MiraclePlus, an accelerator similar to YC, with Lu once again at the helm.
Geoff Ralston succeeded Altman as Y Combinator's president in 2019.
Adapting to the
COVID-19 pandemic
The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...
, Y Combinator conducted its summer 2020 batch remotely. In January 2022, a revised standard deal of $500,000 was introduced, comprising $125,000 for a 7% equity stake and an additional $375,000 via an uncapped safe mechanism incorporating a
Most Favored Nation
In international economic relations and international politics, most favoured nation (MFN) is a status or level of treatment accorded by one state to another in international trade. The term means the country which is the recipient of this treatme ...
(MFN) clause. The summer of 2022 saw a deliberate reduction in the startup intake by 40%, from 414 companies to 250.
In January 2023,
Garry Tan
Garry Tan (; born 1981) is a Canadian-American venture capitalist and executive who is the CEO of Y Combinator and a founder of Initialized Capital. He previously co-founded Posterous and Posthaven. He was an early employee at Palantir Techno ...
assumed the positions of president and CEO, succeeding Geoff Ralston. Tan's leadership marked the discontinuation of the YC Continuity growth fund.
YC moved its headquarters from
Mountain View to
San Francisco
San Francisco, officially the City and County of San Francisco, is a commercial, Financial District, San Francisco, financial, and Culture of San Francisco, cultural center of Northern California. With a population of 827,526 residents as of ...
in the spring of 2023. It had been considering such a move since 2019.
In March 2024, Seibel stepped down as managing director.
Programs
Y Combinator interviews and selects four batches of companies per year. The companies receive a total of $500,000 in
seed money
Seed money, also known as seed funding or seed capital, is a form of securities offering in which an investor puts capital in a startup company in exchange for an equity stake or convertible note stake in the company. The term ''seed'' suggest ...
as well as advice and connections. The $500,000 in funding is made up of $125,000 on a post-money
SAFE
A safe (also called a strongbox or coffer) is a secure lockable enclosure used for securing valuable objects against theft or fire. A safe is usually a hollow cuboid or cylinder, with one face being removable or hinged to form a door. The body ...
in return for 7%
equity and $375,000 on an uncapped SAFE with a "most favored nation" ("MFN") provision (i.e.: "we get the same best terms you give anyone else in the next round"). Non-profits receive a $100,000 donation. The program includes "office hours", where startup founders meet individually and participate in group meetings. Founders also participate in weekly meetups where guests from the
Silicon Valley
Silicon Valley is a region in Northern California that is a global center for high technology and innovation. Located in the southern part of the San Francisco Bay Area, it corresponds roughly to the geographical area of the Santa Clara Valley ...
ecosystem (successful entrepreneurs, venture capitalists, etc.) speak to the founders.
Y Combinator's program is designed to teach founders how to market their product, refine their teams and business models, achieve
product/market fit, and scale the startup into a
high growth business, etc. The program ends with "Demo Day", where startups present their business and technology prototypes to potential investors.
Y Combinator operates additional programs and a fund designed to support and invest in startups which have already graduated from the main accelerator program. The Series A Program, YC Post-A Program, and YC Growth Program are operated by the same team and focus on helping fast-growing YC startups, and startups raising their Series B funding of $20 million to $100 million.
Y Combinator has introduced additional programs since 2015, including:
* In July 2015, Y Combinator introduced the YC Fellowship Program, aimed at companies at an earlier stage than the main program.
The first batch of YC Fellowship included 32 companies that received an equity-free grant instead of an investment.
In January 2016, YC changed the program, with participating companies receiving $20k investment for a 1.5 percent equity stake. The equity stake is structured as a
convertible security
A convertible security is a financial instrument whose holder has the right to convert it into another security of the same issuer. Most convertible securities are convertible bonds or preferred stocks that pay regular interest and can be converte ...
that converts into shares only if a company has an
initial public offering
An initial public offering (IPO) or stock launch is a public offering in which shares of a company are sold to institutional investors and usually also to retail (individual) investors. An IPO is typically underwritten by one or more investm ...
(IPO), or a funding event or acquisition that values the company at $100 million or more. The fellowship was discontinued in 2017.
* In October 2015, Y Combinator introduced the now-defunct YC Continuity Fund. The fund allowed Y Combinator to make
pro rata
''Pro rata'' is an adverb or adjective meaning in equal portions or in proportion. The term is used in many legal and economic contexts. The hyphenated spelling ''pro-rata'' for the adjective form is common, as recommended for adjectives by some ...
investments in their alumni companies. The program was shut down, and staff were laid off in March 2023.
*During 2017–2019, YC launched Startup School, the Series A program, the YC Growth program, Work at a Startup, and YC China.
As of 2025, Y Combinator had invested in over 5,000 companies,
most of which are for-profit, holding a combined valuation of $600 billion. Non-profit organizations can also participate in the main YC program. Few non-profits have been accepted in the last years, among them
Watsi,
Women Who Code
Women Who Code (WWCode) was an international non-profit organization that provides services for women pursuing technology careers and a job board for companies seeking coding professionals. The company aims to provide an avenue into the techno ...
,
New Story,
SIRUM,
Zidisha
Zidisha is a peer-to-peer microlending service that allows people to lend small amounts of money directly to entrepreneurs in developing countries. It is the first peer-to-peer microlending service to link borrowers and lenders across internatio ...
,
80,000 Hours
80,000 Hours is a London-based nonprofit organisation that conducts research on which careers have the largest positive social impact and provides career advice based on that research. The organisation's name refers to the typical amount of tim ...
, and
Our World in Data
Our World in Data (OWID) is a scientific online publication that focuses on large global problems such as poverty, disease, hunger, war, climate change, population growth, existential risks, and inequality.
It is a project of the Global Cha ...
.
Research
In October 2015, YC introduced YC Research to fund long-term fundamental research. Altman donated $10m. Researchers were paid as full-time employees and can receive equity in Y Combinator.
OpenAI
OpenAI, Inc. is an American artificial intelligence (AI) organization founded in December 2015 and headquartered in San Francisco, California. It aims to develop "safe and beneficial" artificial general intelligence (AGI), which it defines ...
was the first project undertaken by YC Research, and in January 2016, a second study on
basic income
Universal basic income (UBI) is a social welfare proposal in which all citizens of a given population regularly receive a minimum income in the form of an unconditional transfer payment, i.e., without a means test or need to perform Work (hu ...
was also announced. Another project was research on new cities.
The Human Advancement Research Community (HARC) project was set up in 2016 with the "mission to ensure human wisdom exceeds human power". The project was inspired by a conversation between Altman and
Alan Kay
Alan Curtis Kay (born May 17, 1940) published by the Association for Computing Machinery 2012 is an American computer scientist who pioneered work on object-oriented programming and windowing graphical user interface (GUI) design. At Xerox ...
. Its projects included modelling, visualizing and teaching software, as well as programming languages. Members included Alan Kay,
Dan Ingalls
Daniel Henry Holmes Ingalls Jr. (born 1944) is a pioneer of object-oriented computer programming and the principal architect, designer and implementer of five generations of Smalltalk environments. He designed the bytecoded virtual machine that m ...
,
Bret Victor,
Vi Hart, and
Patrick Scaglia. HARC was shut down in 2017.
Australian quantum physicist
Michael Nielsen was a research fellow at YC Research from 2016 to 2019.
YC Research disaffiliated with Y Combinator and was renamed to Open Research in 2020.
See also
*
List of Y Combinator startups
*
Hacker News
Hacker News (HN) is a social news website focusing on computer science and entrepreneurship. It is run by the investment fund and startup incubator Y Combinator. In general, content that can be submitted is defined as "anything that gratifies one' ...
*
Techstars
*
500 Startups
500 Global (previously 500 Startups) is an early-stage venture fund and seed accelerator founded in 2010 by Dave McClure and Christine Tsai. The fund admitted a first "class" of twelve startups to its incubator office in Mountain View, Californ ...
*
HighTechXL
*
Entrepreneurs Roundtable Accelerator
References
External links
*
Wonderful Performance formerly Y Combinator China
{{Authority control
Business incubators of the United States
Startup accelerators
Venture capital firms of the United States
Financial services companies based in California
Companies based in San Francisco
Financial services companies established in 2005
2005 establishments in California
Business incubators