My Cofounder Took a Side Project: Is That Betrayal?

You find out on a Wednesday. Maybe it's a stray Slack notification, a LinkedIn update, or a mutual friend who casually mentions it: your cofounder has been working on something else. A side project. Something that isn't your company—the one you've both been pouring nights and weekends into.

Your stomach drops. Your mind races through a dozen interpretations in seconds. Are they checked out? Have they been planning an exit? Are they using your shared resources, your shared network, to build something for themselves?

The discovery that your cofounder has a side project is one of the most emotionally charged moments in a startup partnership. It can feel like infidelity—a secret life running parallel to the one you thought you were building together. But before you fire off a confrontational text or start consulting a lawyer, it's worth pausing to understand what's actually happening, what it means, and what you can do about it.

Because sometimes a side project is a betrayal. And sometimes it's just a missing conversation.

Key Takeaways

• Before confronting your cofounder, assess where their side project falls on the spectrum—from harmless creative outlet to directly competitive shadow startup—so you can calibrate your response appropriately.
• Lead the conversation with observable facts rather than accusations, and clearly name your concern without catastrophizing, to keep the discussion productive.
• Ask yourself whether you ever explicitly agreed to exclusivity, because many cofounder disputes stem from assumptions that were never put in writing.
• Whatever you decide together about the side project, formalize it in a written cofounder agreement covering exclusivity, disclosure requirements, IP ownership, and time commitments.
• Revisit your cofounder agreement quarterly and normalize conversations about outside interests so that side projects never have to become secrets in the first place.

Why a Cofounder Side Project Feels Like a Betrayal

Let's start by validating the feeling, because it's real and it's not irrational.

Startup cofounders operate on an implicit social contract that goes far beyond employment. You're not coworkers splitting tasks on a job; you're partners who've made a high-risk bet with your time, reputation, and often your personal finances. When one person appears to hedge that bet in secret, it threatens something fundamental: trust in mutual commitment.

Here's what's actually being triggered when you learn about a cofounder's side project:

• Fear of asymmetric sacrifice. You've been saying no to freelance gigs, family time, and sleep. If they haven't, the sacrifice suddenly feels one-sided.
• Fear of divided attention. Early-stage startups demand obsessive focus. A side project signals bandwidth going elsewhere.
• Fear of abandonment. If they're building a lifeboat, maybe they've already decided the ship is sinking.
• Fear of deception. Even if the side project is harmless, the fact that you didn't know about it introduces doubt about what else you don't know.

These fears are understandable. But fears aren't facts. Before acting on them, you need to figure out what's actually going on.

The Spectrum: Not All Side Projects Are Equal

A cofounder's side project can mean wildly different things depending on context. Here's a rough framework for thinking about it:

1. The Creative Outlet

Your cofounder is building a small open-source tool, writing fiction, or designing a board game on weekends. It has nothing to do with your industry, generates no revenue, and takes up roughly the same bandwidth as a serious hobby.

Threat level: Low. This is a person maintaining their identity outside the startup. Trying to control this will breed resentment faster than any side project ever could.

2. The Skill-Building Experiment

They're tinkering with a new technology, building a prototype in an adjacent space, or doing a small consulting engagement to stay sharp. It touches your domain loosely, but it's clearly exploratory, not competitive.

Threat level: Low to moderate. The main risk here is scope creep—experiments can turn into companies. This deserves a conversation, not an intervention.

3. The Revenue Side Hustle

They're doing freelance work, running a small e-commerce store, or consulting in a way that generates meaningful income. It's not competitive with your startup, but it's clearly taking real time and energy.

Threat level: Moderate. This might signal financial pressure you didn't know about, or a declining belief in the startup's ability to pay the bills. It requires an honest conversation about runway, compensation, and expectations.

4. The Shadow Startup

They're building something in the same market, talking to the same customers, or using intellectual property, code, or contacts developed through your shared company. They haven't told you about it.

Threat level: High. This is the scenario that genuinely warrants alarm. It's not just a side project—it's a potential competing interest, and depending on your agreements, it may be a legal and fiduciary issue.

The point of this spectrum is to slow down your reaction. Most cofounders who discover a side project immediately jump to scenario four. Most actual side projects land somewhere between one and three.

Before You Confront: Three Questions to Ask Yourself

Once you've taken a breath, interrogate your own assumptions before you bring this to your cofounder.

Did You Actually Agree to Exclusivity?

This is the question that catches most cofounders off guard. You assumed full-time, exclusive commitment. But did you ever say it out loud? Did you put it in writing?

Many founding teams skip the operating agreement, the vesting schedule, even the basic conversation about what "full-time" means. If you never explicitly agreed that neither party would work on anything else, your cofounder may genuinely not believe they're violating any understanding.

That doesn't make your feelings wrong. It means you have a gap in your agreement, not necessarily a breach of trust.

Are You Reacting to the Side Project, or to Something Deeper?

Sometimes the side project is just the surface issue. Underneath, you may have been sensing for weeks or months that something was off: missed deadlines, less enthusiasm in meetings, a growing distance in how decisions get made.

If the side project is a symptom rather than the disease, addressing only the side project won't fix anything. You'll need to talk about the real issue—whether that's burnout, disagreement about direction, or misaligned expectations about equity and compensation.

What Outcome Do You Actually Want?

Before you initiate a conversation, get clear on what you're after. Do you want:

• An apology and an end to the side project?
• A renegotiation of roles and time commitments?
• A formal agreement that prevents this ambiguity going forward?
• An honest assessment of whether your cofounder is still committed?

Knowing your goal will keep the conversation productive instead of letting it spiral into accusations.

How to Have the Conversation

This is the hardest part, and there's no script that works for every situation. But here's a structure that tends to keep things from going sideways.

Step 1: Lead with What You Observed, Not What You Concluded

There's a significant difference between "I saw that you've been working on X" and "You've been secretly building a competing company behind my back." The first invites an explanation. The second invites a defensive argument.

Start with the facts you know and give your cofounder room to fill in context.

Step 2: Name Your Concern Without Catastrophizing

Be honest about what worried you: "When I found out, I felt concerned because I wasn't sure what it meant for your commitment to what we're building. I want to understand where your head is."

This is vulnerable, and vulnerability in a cofounder relationship is a strength, not a weakness. It signals that you care about the partnership enough to be direct.

Step 3: Listen—Actually Listen—to Their Response

Your cofounder might be embarrassed, defensive, or relieved that it's finally out in the open. They might have a completely reasonable explanation you hadn't considered. Or they might confirm your worst fears.

Either way, you need to hear the full answer before deciding what to do.

Step 4: Negotiate a Clear, Written Agreement Going Forward

This is the step most cofounders skip, and it's the most important. Whatever you both decide—whether the side project continues, gets shut down, or gets restructured—put it in writing.

A cofounder agreement should address:

• Exclusivity expectations: Is full-time commitment required? What counts as an exception?
• Disclosure requirements: Must all outside projects be disclosed, regardless of size?
• Non-compete boundaries: Are there specific industries, customers, or technologies that are off-limits?
• IP ownership: Is anything built during the partnership automatically company property?
• Time commitments: What does "full-time" actually mean in hours or deliverables?

Tools like Servanda can help cofounders create written agreements that address exactly these gray areas—before they become full-blown disputes.

A Real-World Example: When the Side Project Saved the Partnership

Consider the story of two cofounders—let's call them Priya and James—who were eighteen months into a B2B SaaS startup. Priya discovered that James had been doing weekend consulting for a company in a tangentially related space. She was furious.

But when they sat down to talk, the picture got more complicated. James was doing the consulting because he hadn't taken a salary in four months and was burning through his savings. He hadn't told Priya because he was embarrassed about his financial situation and didn't want her to think he was losing faith in the company.

The side project wasn't a betrayal. It was a symptom of a broken compensation conversation they'd been avoiding. Once they addressed the real issue—restructuring their equity split and introducing small salaries funded by a bridge loan—the consulting work stopped on its own.

If Priya had led with accusations instead of questions, she might have lost a cofounder who was actually deeply committed but financially desperate.

When It IS a Betrayal: Red Flags That Warrant Escalation

Not every story ends with a hug and a revised operating agreement. Sometimes a cofounder's side project is genuinely a problem. Here are signs that you may be dealing with something more serious than a communication gap:

• They used shared resources. Company funds, proprietary code, customer lists, or introductions from your network went into the side project.
• It's directly competitive. The side project targets the same market, solves the same problem, or could divert customers from your startup.
• There's a pattern of concealment. They didn't just forget to mention it—they actively hid it, lied about their time, or created cover stories.
• They've recruited shared team members. Other employees or contractors are being pulled into the side project without your knowledge.
• They refuse to discuss it. When confronted, they become evasive, dismissive, or hostile rather than engaging in good faith.

If several of these are true, you're no longer dealing with a missing conversation. You're dealing with a breach of fiduciary duty, and you may need legal counsel, a formal mediation process, or both.

Preventing the Problem: Agreements Before Emotions

The best time to address the cofounder side project question is before it happens. The second-best time is right now.

Every founding team should have a written agreement that covers outside work before anyone has a reason to be defensive about it. Here's a practical checklist:

1. Draft an exclusivity clause that's specific and realistic—not a blanket "you can never do anything else," but a clear boundary that protects the company's interests.
2. Build in a disclosure mechanism. Make it easy and low-stakes for either cofounder to say, "Hey, I'm thinking about doing X on the side. Here's why and here's how it won't affect us."
3. Revisit the agreement quarterly. Circumstances change. Financial pressures shift. What was reasonable in month three may not be reasonable in month eighteen.
4. Tie commitment to vesting. A well-structured vesting schedule with a cliff naturally protects against a cofounder who checks out early. If they leave or reduce commitment, the equity structure reflects that.
5. Normalize the conversation. The goal isn't to create a surveillance culture—it's to make talking about outside interests as routine as talking about product roadmaps.

Conclusion

Discovering your cofounder has a side project is jarring. It can feel like a betrayal, and in some cases, it genuinely is one. But more often, it's the consequence of an agreement that was never made explicit—a gap in understanding that both of you share responsibility for.

The path forward starts with honest questions, not accusations. It requires understanding the spectrum between a harmless creative outlet and a competing venture. And it demands that whatever you decide, you put it in writing so you never have to navigate this same ambiguity again.

The strongest cofounder relationships aren't the ones that never face conflict. They're the ones that build the structure to handle it before the emotions take over.

Frequently Asked Questions

Is it normal for a cofounder to have a side project?

It's more common than most founders expect, especially when salaries are low or nonexistent in early-stage startups. A side project doesn't automatically signal disloyalty—it may reflect financial pressure, creative needs, or simply the absence of a clear exclusivity agreement between cofounders.

Should cofounders sign a non-compete or exclusivity agreement?

Yes, every founding team should have a written agreement that spells out exclusivity expectations, disclosure requirements, and non-compete boundaries before any conflict arises. The agreement should be specific and realistic rather than an overly broad blanket restriction, and it should be revisited as circumstances change.

How do I tell if my cofounder's side project is actually a competing business?

Key red flags include the side project targeting the same market or customers, using shared company resources like proprietary code or customer lists, and your cofounder actively concealing the work or recruiting shared team members into it. If multiple red flags are present, you may be dealing with a breach of fiduciary duty rather than a simple communication gap.

What should I do if my cofounder lied about their side project?

A pattern of active concealment—lying about their time, creating cover stories, or refusing to discuss it when confronted—signals a serious trust violation that goes beyond a missing conversation. In this situation, consider seeking formal mediation or legal counsel, and document everything in writing to protect your interests and the company's.

How do I bring up my cofounder's side project without starting a fight?

Start by stating what you observed factually, then share how it made you feel and what concerns it raised about commitment, without jumping to conclusions. Give your cofounder space to explain the full context, and steer the conversation toward a concrete, written agreement about expectations going forward rather than dwelling on blame.