Y Combinator

The complete archive of Y Combinator (2005-2026), from a walk home in Harvard Square to the most influential startup accelerator in the world. The full institutional history interwoven with YC's entire video library: every Startup School lecture, How to Start a Startup class, founder story and talk, from Zuckerberg in 2012 to the AI era. Hundreds of hours of the people, ideas and companies that built Silicon Valley's engine room.

A chronological documentary of 710 moments spanning 2005–2026 on Loreline.

Curated by Olivier · last updated 2026-09-20

1. 2005-03-11 - The walk home from Harvard Square. On 11 March 2005, walking home from dinner in Harvard Square, Paul Graham and Jessica Livingston decide to start their own investment firm rather than have Jessica take a job at a Boston VC. By the time they reach Walker Street, Y Combinator exists in all but name.
2. 2005-03-12 - Paul Graham. A Lisp hacker, essayist and the co-founder of Viaweb (sold to Yahoo in 1998), Paul Graham brings the idea, and the essays, that shape Y Combinator’s philosophy: fund founders early, in batches, and "make something people want".
3. 2005-03-13 - The four founders. Y Combinator is founded by Paul Graham, Jessica Livingston, and Graham’s old Viaweb partners Robert Tappan Morris and Trevor Blackwell. The initial fund is $200,000, $100,000 from Graham, $50,000 each from Morris and Blackwell.
4. 2005-03-14 - Trevor Blackwell. "Y Combinator", a concept from computer science, replaces "Cambridge Seed" within days, to signal national rather than regional scope.
5. 2005-06-01 - The Summer Founders Program. Instead of investing one startup at a time, they decide to fund a whole batch over the summer of 2005. Graham’s reasoning: "we wanted to learn how to be angel investors, and a summer program for undergrads seemed the fastest way to do it." 8 startups are chosen from ~225 applications.
6. 2005 - The first 6 months of Reddit (YC 05)- "Entrepreneurship is a bipolar existence". "
7. 2005 - the Reddit founders (2005). the Reddit founders, photographed in 2005. Part of the Y Combinator story.
8. 2005 - Geoff Ralston (2005). Geoff Ralston, photographed in 2005. Part of the Y Combinator story.
9. 2005 - How OpenAI CEO Sam Altman applied to YC's FIRST Batch in 2005. The Social Radars Podcast
10. 2005 - Reddit joins the first batch. Among the first 8 startups, alongside Loopt and Kiko, are Steve Huffman and Alexis Ohanian, whose idea YC redirects into Reddit. The original deal: about $6,000 per founder, and weekly dinners run out of Graham and Livingston’s house in West Cambridge.
11. 2006 - the Reddit founders (2006). the Reddit founders, photographed in 2006. Part of the Y Combinator story.
12. 2006-10-31 - Reddit’s exit - the first big win. In October 2006, just over a year after the first batch, Reddit is acquired by Condé Nast. The early validation that the batch model can produce real outcomes, and proof that funding very young founders works.
13. 2007-02-19 - Hacker News launches. Paul Graham launches Hacker News (originally "Startup News") in 2007, a community link aggregator that becomes the front page of the startup world and a recruiting and reputation engine for YC itself.
14. 2007-06-01 - Dropbox (Summer 2007). Drew Houston applies to YC with a file-syncing demo and is told to find a co-founder; he brings in Arash Ferdowsi and joins the Summer 2007 batch. Dropbox becomes one of YC’s defining early successes.
15. 2007 - Paul Graham (2007). Paul Graham, photographed in 2007. Part of the Y Combinator story.
16. 2007 - the Twitch founders (2007). the Twitch founders, photographed in 2007. Part of the Y Combinator story.
17. 2007 - Jessica Livingston (2007). Jessica Livingston, photographed in 2007. Part of the Y Combinator story.
18. 2008-04-19 - Startup School. YC runs Startup School, free day-long events where famous founders speak to a hall of would-be entrepreneurs. It spreads YC’s ideas far beyond the funded batches and seeds the global founder community.
19. 2008 - Paul Graham at Startup School 08. startupschool
20. 2008 - the Collison brothers (Stripe) (2008). the Collison brothers (Stripe), photographed in 2008. Part of the Y Combinator story.
21. 2009-01-15 - Consolidation in the Valley. In January 2009 the Cambridge program closes and YC consolidates entirely in Silicon Valley. The same year, Sequoia Capital leads a $2 million investment that lets YC fund around 60 companies a year.
22. 2009-01-20 - Airbnb (Winter 2009). Brian Chesky, Joe Gebbia and Nathan Blecharczyk join the Winter 2009 batch after famously funding themselves selling cereal boxes. Graham’s advice, go to your users, helps turn Airbnb into one of YC’s biggest companies.
23. 2009-06-01 - Stripe (Summer 2009). Patrick and John Collison join YC and build Stripe, developer-first payments. It becomes one of the most valuable private companies in the world and a cornerstone of the YC portfolio.
24. 2009 - Y Combinator (2009). Y Combinator, photographed in 2009. Part of the Y Combinator story.
25. 2009 - Paul Graham on Start-ups, Innovation, and Creativity 08/03/2009. EconTalk
26. 2010 - Geoff Ralston (2010). Geoff Ralston, photographed in 2010. Part of the Y Combinator story.
27. 2010 - Brian Chesky - Founder of Airbnb @ Startup School 2010 (1 of 2). Ernest
28. 2010 - Sequoia doubles down. In 2010 Sequoia provides a further $8.25 million, and YC adds partners and advisors, Paul Buchheit (creator of Gmail) and Harj Taggar among them, to handle the growing batches.
29. 2010 - Jessica Livingston (2010). Jessica Livingston, photographed in 2010. Part of the Y Combinator story.
30. 2010 - This Week in Startups - Garry Tan, Co-Founder of Posterous. This Week in Startups
31. 2011 - Y Combinator (2011). Y Combinator, photographed in 2011. Part of the Y Combinator story.
32. 2011 - Drew Houston (Dropbox) (2011). Drew Houston (Dropbox), photographed in 2011. Part of the Y Combinator story.
33. 2011 - Brian Chesky (Airbnb) (2011). Brian Chesky (Airbnb), photographed in 2011. Part of the Y Combinator story.
34. 2011 - Y Combinator's Graham Says Startups Must Improve Lives. Bloomberg Originals
35. 2011-10-15 - Startup School draws the Valley’s biggest names. By 2011 Startup School fills auditoriums; Mark Zuckerberg and Ashton Kutcher speak. YC has become the center of gravity for early-stage startups, and a YC badge is a signal in itself.
36. 2012 - Justin.tv's Justin Kan: The story of a serial entrepreneur | Wizard. Justin.tv's viewers watch 300+ million videos a month. Socialcam just sold for $60 million. Now serial entrepreneur, Justin Kan, has founded Exec, which makes it possible to get jobs done without middlemen, and gives a whole class of people an opportunity to make a living.
37. 2012 - Y Combinator's Graham Doesn't See `Bubble' in Technology: Video. Bloomberg Originals
38. 2012 - Loopt's Altman Says Groupon Partnership Looks Promising. Bloomberg Originals
39. 2012 - Drew Houston: How I Met My Co-Founder. Stanford eCorner
40. 2012 - Y Combinator's Paul Graham On Changing Strategies. TechCrunch
41. 2012 - Jason Interviews Sam Altman CEO of Loopt. TechCrunch
42. 2012 - Paul Graham On Founder Power, The Rise Of NY. TechCrunch
43. 2013 - Goodreads, Y Combinator Demo Day, and Bitcoin | CrunchWeek. TechCrunch
44. 2013-08-15 - DoorDash at YC Summer 2013 Demo Day. From the Y Combinator video archive (2020).
45. 2013-10-25 - Joel Spolsky at Startup School 2012. From the Y Combinator video archive (2013).
46. 2013-10-25 - Hiroshi Mikitani at Startup School 2012. From the Y Combinator video archive (2013).
47. 2013-10-25 - Tom Preston Werner at Startup School 2012. From the Y Combinator video archive (2013).
48. 2013-10-25 - David Rusenko at Startup School 2012. From the Y Combinator video archive (2013).
49. 2013-10-25 - Jessica Livingston at Startup School 2012. From the Y Combinator video archive (2013).
50. 2013-10-25 - Ron Conway at Startup School 2012. From the Y Combinator video archive (2013).

…and 660 more moments.

Full text archive: /loreline-text/y-combinator.md