How to find a cofounder: a step-by-step search plan

Decide whether you need a cofounder, and for what

Short answer: find a cofounder by writing down the exact gap you need filled, sweeping your own network first, then going where builders already spend time, and testing every promising person in a few structured conversations and a small project before anyone signs anything. The search usually takes longer than founders expect, so treat it as a project with a weekly rhythm, not as a post you write once and wait on.

First, check that you need one. Y Combinator partner Aaron Harris put it bluntly: you do not need a cofounder to start a company, a great one makes it much easier, and a bad one usually kills it. Paul Graham listed going solo as the first of his startup mistakes, mainly because you need someone to brainstorm with, to talk you out of bad decisions and to keep you going through the low points. Carta's data on startups using its platform points the same way: in 2025 solo founders started 36% of new companies but raised only 20% of the rounds closed on Carta that year, while two-founder teams raised 36%.

If you decide you do need someone, answer three questions before you look:

• What has to happen before your next real milestone, such as a first paying customer or a working pilot?
• Which of those things can you not do yourself, and will that stay true for years?
• Which of them could you simply pay a contractor for? Anything you can buy for cash should not cost you a share of the company.

Write a one-paragraph cofounder brief

Most searches stall because the founder is looking for "a cofounder" in general. A short brief fixes that. It forces you to say what you bring, what is missing and what you are offering, and it becomes the raw material for every profile, post and message you write later. Fill in the brackets below. If a line is hard to write, that is the conversation you are not ready to have yet.

Keep the equity line honest but open. Y Combinator's Michael Seibel recommends equal or near-equal splits between founders, because most of the work is still ahead of you. Saying early that you expect something close to equal, with vesting, removes a lot of suspicion from the first conversation.

I am building: [the problem, for whom, in one sentence]
So far: [evidence: customer interviews, a prototype, users, revenue]
I bring: [your skills and something you have shipped]
The gap: [the core work you cannot do, e.g. build the product, sell to hospitals]
Commitment: [hours per week now, when you go full-time, how long you can go without salary]
Equity: [close to equal, with four-year vesting and a one-year cliff, open to discuss]
Where: [city or remote, time zone]
Next step: [a 30-minute call, then a small project together]

Sweep your own network before strangers

Y Combinator's advice is that the most likely place to find a cofounder is among your friends and the people you have already worked with on projects. You already know how they behave when a deadline slips, which is the thing a stranger's profile can never tell you. Do the sweep on paper, so you do not skip people just because they did not come to mind.

Harris adds a useful twist: if someone on your list is very smart but not right for you, talk to them anyway and ask who they know that you should meet. One referral from a person you respect is worth more than a stack of cold matches.

• List people from every job, course, side project, hackathon and community you have been part of. Aim for breadth first, judgment second.
• Mark each name on three things: would I want to work closely with them for years, could they cover the gap in my brief, and might they be ready to move in the next year?
• Message your top five with the brief and a specific ask for a call.
• Ask everyone else for one name: "Who is the best [engineer, seller, designer] you have worked with who might want to start something?"

Go where builders already spend time

When your own network runs dry, go where people are already building or already looking. The common thread in the channels below is that you see people do something, not just describe themselves. Pick two that fit your field and show up every week rather than sampling ten once.

• Hackathons and build weekends: you see how someone works against a real deadline in a day or two, which is close to a free trial.
• Meetups and communities in your field: be useful first. Answering questions and sharing what you learned attracts better people than a post that says "looking for a CTO".
• Accelerators and university programs: many run founder mixers or team-formation sessions before the program starts.
• Open source projects and online builder groups: the work is public, so you can read someone's code or writing before you ever reach out.
• Dedicated matching platforms: Y Combinator Co-Founder Matching is free, takes no equity, and profiles are visible only to other approved users, not the public internet. Solution is another route built for this search; the steps are in section 08.

Reach out with a message that earns a reply

A good first message is short, specific and shows you looked at the person, not just their job title. Lead with why them, give one line of evidence that the idea is real, and ask for something small. Leave out the billion-dollar vision and never frame the role as building your app for equity; you are offering a partnership, not an unpaid job.

Send it, follow up once after a week with a real update, and then let it go. People who are not ready this quarter are often ready next year, and a respectful first contact keeps that door open.

Hi [name],
[Mutual contact] mentioned you built [specific thing], and that is exactly the part I am missing.
I am working on [problem, for whom]. So far [one piece of evidence, e.g. 20 customer interviews and a clickable prototype].
I am looking for a [technical / commercial] cofounder and expect a close-to-equal split with vesting.
Would you be open to a 30-minute call next week, with no commitment beyond that?
[Your name]

Run three conversations, each with a job

Chemistry on a first call is easy and tells you little. Give each conversation a job, so by the end you have tested the things that actually break founding teams: motivation, money, time and how you decide.

• Conversation 1, why: why this problem, why now, what each of you wants your life to look like in five to ten years, and what would make you quit.
• Conversation 2, the hard topics: hours per week, months of runway without salary, who does what day to day, who decides when you disagree, and equity. Raise the split here, not after months of work; Seibel's typical setup is four-year vesting with a one-year cliff, so someone who leaves early does not walk away with half the company.
• Conversation 3, work: spend two or three hours on a real task together, such as planning customer interviews or sketching the first version. Watch how ideas get challenged.
• If all three go well, run a short, bounded project before you commit. We wrote a full guide on that: the cofounder trial project.

Know the red flags, and when to keep looking

Stop and think twice if someone goes quiet for a week during the courtship, asks for a large share before doing any work, only talks about the exit and never about the customer, or refuses any kind of trial. Someone who is unavailable now will not suddenly become available when production breaks at 2am.

Some things only look like flags. A day job is normal at the start; agree on when and how it ends. Disagreeing with you is a good sign, because a partner who always says yes is not helping. And if after a few months no one fits, it is fine to keep going solo, hire for the gap and keep the brief ready. Harris's warning cuts both ways: no cofounder beats the wrong one. If what you really need is an early employee rather than an owner, read how to make your first startup hire.

Find your cofounder on Solution

Once your brief is written, the search is mostly about meeting enough of the right people, and that is what we built Solution for: finding the right person and starting a conversation that has a reason. Everyone on Solution says what they help with and what they are looking for, so you can see straight away who is open to starting something and what they bring. Every Smart Connections pick comes with a plain reason why that person fits you, which makes a great first line for your message. And because replies to your request land in one place, you are not chasing threads across five apps. Here is how to run the search in the app:

• Create your profile and paste in your brief: what you are building, what you bring and the gap you need filled.
• Post a Co-founder request and pick the role you need, for example CTO, CMO or Product Manager. Say what you are building, what you offer and where you are. You can post as yourself or as your startup, and every reply comes to you in one place.
• Search for people yourself by what they help with, what they are looking for, whether they are open for work, and their field and location.
• Turn on Smart Connections: answer a four-tap questionnaire and get people picked for you, each with the reason, such as what you need, how you work and where you are. Use that reason in the opening line of the message template above.
• Set up your startup page for free: what you do, your stage, whether you are raising and the roles you need, so anyone you reach out to sees the full picture.
• When you find someone, take them through the three conversations and the trial project above.
• What is free and what needs Membership: a profile, exploring the network, following people and startups, a startup page and your first three messages are free, and you can see that Smart Connections has picked people for you. Membership lets you message anyone directly, see who those picks are and why each one fits, post and answer requests, and use the Investor Desk, appear in the directory, join events and share posts and articles.