The co-founder guide: What I’ve learned from 1,000+ startups

- Julian Weisser, co-founder and CEO of ODF

I co-founded ODF, a week-long, cohort-based program to help people meet collaborators, explore ideas, and launch companies. Through that experience, I've developed deep insights into what makes co-founder relationships work or fail.

In five years, over 3,000 people have done ODF, resulting in over 1,000 startups — and the founders of many top companies met their co-founders during it. This has given me a unique perspective of what works, what doesn't, and what to consider when looking for a co-founder.

Co-founder dynamics

Choosing the right co-founder is the most important decision you’ll make. You might read that and think I’m flat out wrong — isn’t the idea most important? Make no mistake, markets matter a lot. Product too. But if you expect the thing that annoys you about a potential co-founder today will change because they’ll “grow” I’ve got bad news. You and your co-founder won’t change as much as the ideas you might explore together.

The relationship you form will define not just your company's future, but a significant portion of your life. You'll probably spend more time with your co-founder than anyone else, and much of that will involve navigating tough decisions, disagreements, and conflict — and that’s the fun part! Most successful companies nearly die at some point, and almost everyone loses faith. Will you stick it through together?

Most people think companies die because they run out of money. But in my experience, they often fail because co-founders lose faith in each other first. Ideas change, but people don’t. If you’re working with this person five years down the line, you want to feel grateful for their consistency — not frustrated that they haven’t become the person you hoped they’d be.

Want more context on co-founding startups? Watch this video from TechCrunch Disrupt 2024.

Common pitfalls in co-founder selection

At ODF, I've watched hundreds of potential partnerships form and dissolve. Here are the common mistakes founders make when choosing partners:

Assuming shared vision without deep discussion

Getting along well in casual settings or sharing similar backgrounds doesn’t guarantee alignment on what matters most. You need to go deep with them about what both of you want. Discuss scenarios around success and failure, expectations around multi-year timelines, and what success means to each of you. If one sees a million dollars in revenue as success, and the other aims for two hundred million, you don’t share the same vision. And that’s okay, but you need to know it early.

Assuming you’re more likely to succeed co-founding with someone you’ve worked with previously.

Conventional wisdom suggests it’s better to work with someone you know than a recent acquaintance. There are benefits to starting with someone you’ve known for a while, but I’ve seen people get a false sense of security. It’s easy to make incorrect extrapolations from past relationships that might seem similar but also have major differences from starting a startup. Being an excellent IC or manager at a growth-stage startup is not a direct 1:1 transfer of necessary skills.

Trying to convert the reluctant

If someone’s unsure about being a co-founder — maybe they have a high-paying job in big tech, and they like the predictability and ease of that job — then they’re not the right choice. When your potential co-founder is on the fence, they’ve decided not to be your co-founder. The best partnerships start with mutual enthusiasm and conviction. You want someone running toward the opportunity, not someone you have to pull along.

Prioritizing the idea over the partnership

I often see founders fixated on their initial idea, treating potential co-founders like employees to execute their vision. Great companies come from excellent partnerships and, frequently, an initial series of failed ideas. Slack, which started as an internal messaging board for a now-defunct online game, is a famous example, but countless companies pivot before landing on something great.

Being too attached to your initial concept can blind you to better ideas and better partners. Some of the strongest founding teams I’ve worked with came together first around shared values and complementary skills, then explored various ideas together until they found the right one. There’s value in forming a partnership, then narrowing in on an idea together.

Essential qualities in a co-founder

Based on observing thousands of founders at ODF, here are the qualities I believe  lead to strong partnerships:

Complementary capabilities

You can hire for many roles later, but having different but complementary skills between co-founders creates a strong foundation. If you’re building a software product and lack a technical background, you’ll want a co-founder with deep technical knowledge.

Productive disagreement

In a company’s lifespan, you’ll encounter countless disagreements. This is a good thing. You want a co-founder who has the confidence to disagree with you and the tact to do so productively. The strongest partnerships I’ve observed aren’t free from conflict — they just handle it constructively.

Bias toward action

This person needs to work with a bias towards action. When faced with uncertainty or obstacles, do they find ways forward? The early days of a startup require constant problem-solving and initiative — you need someone who takes action rather than waiting for direction.

Mutual inspiration

Starting a company can be grating and exhausting. Your co-founder should inspire you to level up and work harder. After a brainstorm session with your co-founder, you should feel energized and excited. The best co-founder relationships have mutual inspiration — each person brings out the best in the other.

After finding your co-founder

Finding the right co-founder is crucial, but structuring your partnership thoughtfully is equally important. I’ve seen too many otherwise strong relationships strain under poorly designed agreements. The goal isn’t just to protect the company — it’s to create a framework that helps your partnership thrive through difficult times.

Decisions like vesting schedules should prioritize the company’s health; longer vesting schedules, even up to eight years, can help ensure that company equity isn’t taken up by someone who ends up leaving. More importantly, these structures create alignment between co-founders over the long term.

Still searching?

Stay open. While traditional paths to finding co-founders still work — like starting companies with former colleagues or classmates — the world has changed for the better. You could meet your co-founder through an accelerator or program like ODF, a community like Mercury Raise or Merge Club, or by asking for referrals from friends and teammates.

Don’t rush into a co-founding relationship just because you want to start building. I’ve seen many successful companies where co-founders joined after initial traction or funding. Some strong partnerships formed when solo founders had proven early demand first. The key is finding the right person, not finding someone quickly.