At some point, usually right after your startup starts to feel like a “real company”, someone will ask the question.

“Should we split the codebase?”

This might often sound sensible or grown-up, even. Multiple teams. Clear ownership and architecture. This is the kind of decision that feels like progress, right? It is also one of the most reliable ways early-stage companies accidentally slow themselves down.

Let’s get one thing out of the way: this is not a technical debate. Or at least, not primarily. The choice between one codebase or multiple repositories has far more to do with people, communication, and organisational maturity than with software design.

Which is exactly why founders and investors should care about it. Read on to find out why.

Monorepo vs multi-repo

A single codebase, often called a monorepo, means all your software lives together. Frontend, backend, maybe some shared logic. One place. One version of reality.

Multiple repositories mean things are split up. Different services, different teams, different rules. In theory, this brings more autonomy. In practice, it usually leads to greater coordination.

The early days favour focus, not structure

Early on, most startups do not have a coordination problem. They have a focus problem.

Everyone still talks to everyone. Decisions are made in the same room, or at least in the same Slack channel. Changes happen fast because feedback loops are short, and when something breaks, people notice immediately.

In that context, splitting the codebase adds friction without removing any real bottleneck. You introduce boundaries you do not yet need, and you start paying for them every single day.

Every extra repository comes with overhead. Not the dramatic kind that shows up in dashboards, but the slow, compounding kind. More meetings. Longer discussions about interfaces. More time spent figuring out where something should live. More chances for parts of the system to drift apart.

None of this feels catastrophic, and that is exactly the danger. It feels like paper cuts.

It can be uncomfortable at times, but discomfort is not the same as inefficiency.

We will need to do it later anyway

The usual argument for splitting early is “we’ll need it later anyway”. It sounds prudent, almost responsible, but it often isn’t.

Later, you will indeed have different problems. You will have new people, different constraints, and other usage patterns. Decisions made today to serve a hypothetical future team tend to age badly, because that future rarely shows up exactly as imagined.

What does show up is complexity. And complexity always comes with a cost.

For non-technical founders, the impact is subtle but real. Delivery slows down and engineers start talking about dependencies or coordination instead of outcomes. Small changes take longer than expected. Nobody can quite explain why, but everyone feels it.

For investors, this usually surfaces during audits. Teams look busy but move cautiously. Systems are “nicely separated” yet strangely hard to evolve. The architecture assumes an organisational maturity the company does not actually have.

This is not because multiple repositories are bad. They are often the right choice.

The key word is later.

When splitting codebases actually starts to pay off

Splitting a codebase only really pays off once teams are genuinely independent. That means independent roadmaps and release cycles, clear ownership, and stable interfaces. It also means people can make decisions without constantly synchronising with everyone else.

Until that point, separation mostly creates the illusion of scalability.

A single codebase forces conversations to stay concrete. You see the impact of changes immediately. Shared context is harder to avoid, and coordination happens implicitly because everyone is working in the same place.

That can be uncomfortable at times, but discomfort is not the same as inefficiency.

There is a reason many successful companies stayed on one codebase far longer than their architecture diagrams suggested they should. Not because they did not know better, but because they optimised for momentum. And early on, momentum matters more than elegance.

The irony is that teams who wait longer to split often do it better when the time comes. By then, they have learned where the real boundaries are. Not the theoretical ones, but the ones shaped by usage, ownership, and failure modes.

They split because coordination cost has become the bottleneck, not because growth feels imminent.

Architecture is a people problem

From the outside, this decision often looks technical. From the inside, it is deeply human.

It is about how often people need to talk to each other, how much context lives in their heads, and how confident they feel making changes. It is also about how tolerant the organisation is of small mistakes, and how quickly it can recover from them.

Architecture that works with those realities tends to age well. Architecture that fights them tends to become brittle, no matter how clean it looked on day one.

So when a founder is asked whether the team should split the codebase, the most useful follow-up question is not “what is best practice?”

It is “what problem are we actually trying to solve right now?”

And for investors reviewing a technical setup, early fragmentation is worth a closer look. Not as a red flag, but as a signal. It often says more about organisational ambition than organisational readiness.

Conclusion: Timing beats correctness

One codebase versus multiple repositories is not about technical purity. It is about timing and about being honest with where your organisation is today.

Early on, shared context and fast feedback matter more than clean separation. One codebase keeps teams aligned, makes trade-offs visible, and favours momentum over elegance. That is usually a good deal in the early stages of a company.

Splitting starts to make sense once coordination itself becomes the bottleneck. When teams can operate independently, ownership is clear, and interfaces are stable, separation stops being overhead and starts creating leverage.

Until then, structure can feel like progress while quietly slowing things down.

For founders, the useful question is not what best practice says, but which problem you are actually trying to solve right now. For investors, early fragmentation is less a red flag than a prompt for better questions.

Get the timing right, and the architecture fades into the background. Get it wrong, and you pay for it quietly, every day.