YC Co-Founder Matching Guides

Read the Startup School FAQ before you join

The Startup School FAQ sets the rules. Profile approval may take up to a week. The service caps invitations at 15 a week, which the FAQ says is to prevent spam. It suggests two to four weeks of close work before you decide on a match, and it lists seven questions to ask a match after you connect. It also says joining does not improve your chances of getting into YC, so do not join for that reason. ^[1]

Plan around 15, not 20. Founder Compass, a review updated October 11, 2026, says the product now allows 20 a week while citing the FAQ for 15. At 15 a week, a month of outreach reaches 60 people at most, so the cap limits how many people you can contact. Plan on 15 because it is the figure YC publishes. ^{[1] [12]}

YC’s 2021 blog is the only official data with counts, and it is old

What do people want in a co-founder? was published October 21, 2021, about three months after launch. It reports that 31% of founders do engineering, that 80% of non-engineers prefer an engineering co-founder, and that half of matches are accepted within 22 hours. It also says 68% of matches pair a technical founder with a non-technical one. Read it for who joins and how quickly people reply in the platform’s first months. It describes matching, not whether a match becomes a company, and the post is promotional in tone. ^[2]

Two success stories show the trial, not a success rate

Does co-founder matching work? It did for these YC companies. (November 24, 2021) profiles two pairs who met on the platform, went through YC and raised money. The useful part is the sequence. One pair worked together for a month before committing. In one case, the co-founders spent four months remote before they met in person. Two stories have no denominator, so they cannot give a success rate. Use them as a model for a trial before you commit. ^[3]

Read the 10-question post before you agree to anything

YC’s 10 Questions to Discuss with a Potential Co-founder (April 27, 2023) lists the topics to settle first: why you are starting, who is CEO, the equity split, location, whether you would change the idea, milestones before going full-time, finances, schedule, hiring and culture, and how you handle disagreements. Start with the equity split and the CEO role, since those are the hardest to reset once work begins. The post says full compatibility “usually takes several months to know for sure,” so a short trial will not settle everything. It links a Google Doc to use as a template, but it is a conversation guide, not a legal agreement. ^[4]

Watch YC’s own video for the official framing

How To Find A Co-Founder | Startup School is the Y Combinator video on finding a co-founder. The page gives only the title and channel, so the length and content are yours to judge when you press play. Watch it before you write your profile, since the profile is the first thing YC approves. ^[5]

The second YC video is a lead, not a guide

How to Find the Right Co-founder is also a Y Combinator video, with the same limit: the page shows only its title and channel. Watch it after the first video if you want more on choosing someone. Without a length or description, you cannot tell whether it covers this platform or co-founder search in general. ^[6]

Use the call template for a first meeting, with one catch

A free co-founder meeting template, a GitHub gist created May 17, 2024, gives you a fill-in for a first call: the other person’s profile links, background, current work, prior startup experience, and priorities for the first three to six months. The questions suit a call before a trial. The catch: it has one revision, no license is shown, and some questions are ‘inspired by’ YC’s list without saying which. Treat it as a checklist, not an official YC document. ^[7]

A written digest of YC’s videos, with the trial and equity points

Y Combinator Startup School Playlist Summarized, a GitHub gist by an individual author (last active March 22, 2026), condenses YC’s Startup School videos, including a co-founder section. Its co-founder points are trial projects before committing, an equal equity split and clear CEO roles. It is the author’s paraphrase, not the videos, so use it to decide which video to watch rather than as a quote. ^[8]

Use the message templates, skip the statistics

YC Co-Founder Matching: How It Works + Free Message Templates comes from YC Insight, which says in its footer that it is unaffiliated with Y Combinator. The templates need no sign-up. They include a profile fill-in and first messages for a technical founder writing to a business founder, a business founder writing to an engineer, and a note to someone with an idea. Its figures are a different matter. ‘150,000+ active profiles’ and ‘3–6 months to match’ have no source, and the site sells a database, application rewrites and a cheatsheet behind an email form. ^[9]

Use the steps from a firm that sells vetting

YC Co-Founder Matching: How It Works and Who Gets In, from RocketDevs (June 11, 2025), lays out the steps: a profile, filters for skills and stage, a message, then a call ‘ideally, within a few days.’ It suggests informal vetting questions and a short joint project, such as a one-week prototype or a hackathon. RocketDevs sells developer vetting, and its timing is inconsistent. It gives a 100-day median credited to YC, but the link behind that figure is a third-party document, so do not repeat it. ^[10]

A recent secondary read that repeats YC’s rules

YC Co-Founder Matching: How It Works and Who Gets In, from Round Funded (September 26, 2026), is the newest guide here. It walks through seven steps from profile to approval to invitations with a personal note, and it puts equity after the 2–4 week trial. Its approval wait, 15-invite cap and trial length match the FAQ, so it adds no new rules. Round Funded sells fundraising tools, so use it to check the steps, not its figures. ^[11]