Monorepo vs. Multi-repo for a Solo Developer — A 1-Year Retrospective

Monorepo vs. Multi-repo for a Solo Developer

Exactly one year ago, I made a major architectural decision for my software engineering projects: I systematically migrated all my distinct codebases into a single, highly unified monorepo using the powerful combination of pnpm workspaces and Turborepo. At the time, I genuinely believed this was the ultimate, flawlessly optimized setup for a solo developer desperately trying to scale multiple Software-as-a-Service (SaaS) products simultaneously. Fast forward to today, and my perspective has evolved significantly after intimately facing the harsh, exhausting realities of maintaining a rapidly growing monorepo completely alone. In this detailed retrospective, I will openly share the immense benefits I experienced, the painfully frustrating bottlenecks that almost entirely broke my workflow, and precisely why I eventually decided to partially revert to a multi-repo strategy for specific backend projects.

The Bright Side: Why Turborepo Felt Like Magic

Adopting the pnpm workspaces and Turborepo architecture brought three immediate, revolutionary advantages to my daily coding workflow. First and foremost was the incredible ability to create internal shared packages. I could write a beautiful, highly customized React UI component or a complex mathematical utility function just once, and seamlessly import it across five different web applications without ever needing to publish it publicly to npm. You can learn more about this brilliant tooling directly at the Turborepo official site.

Second, maintaining central, absolute control over TypeScript configurations and ESLint strict rules was a massive time-saver. Instead of agonizingly manually updating linting rules in ten completely different repositories, I effortlessly managed a single source of truth at the root level. Read my about page to truly understand how obsessed I am with maintaining clean, readable code. Finally, the atomic commit capability was nothing short of revolutionary. If I needed to radically update a core API data payload, I could safely modify the backend logic, update the shared TypeScript interfaces, and adjust the frontend UI components all within a single, cohesive Git commit and a single Pull Request. This strictly guaranteed that my client and server were never disastrously out of sync.

"The ROI of a monorepo peaks beautifully when your tech stacks and business domains perfectly align. Once they diverge, the monorepo becomes a prison."

The Dark Side: When the Monorepo Breaks You

However, as the monorepo ambitiously grew in size and complexity, three incredibly painful and critical disadvantages inevitably emerged to haunt me:

1. The Butterfly Effect Failure: The most traumatizing incident happened on a late Friday evening. A simple, stupid typo in a deeply buried configuration file within the `legal-kr` package—a minor, seemingly harmless module handling Korean legal privacy text—triggered a massive cascading failure. This single typo aggressively paralyzed the CI/CD deployment pipeline for my flagship portal application for over 3 excruciating hours. Because absolutely everything was interlinked, a tiny failure in a leaf node completely broke the root build.
2. Exploding CI/CD Times: My Continuous Integration (CI) execution times skyrocketed out of control. What historically used to take a brisk, satisfying 2 minutes to smoothly build and deploy now took an agonizing, focus-destroying 20 minutes, rapidly draining both my personal patience and my costly server resources. Check out pnpm for excellent caching strategies, but realistically, sometimes caching alone isn't enough to save a bloated pipeline.
3. Framework Upgrade Nightmares: The incredibly tight coupling became a literal nightmare when dealing with major framework upgrades. Upgrading the entire ecosystem to React 18 meant I was forced to update, thoroughly test, and debug every single project in the monorepo simultaneously, which is an overwhelmingly impossible task for a single solo developer with limited hours in the day.

The Breaking Point and The Multi-repo Revival

The final breaking point was the introduction of my brand new experimental project, `saas-factory-trader`. This specific application was heavily based on Python and persistent real-time WebSockets, which was a completely alien technology stack and business domain compared to my standard Next.js and TypeScript-heavy web applications. Trying stubbornly to force this distinct Python project into my strictly Node.js-centric Turborepo ecosystem was an unmitigated architectural disaster. I finally decided to swallow my pride, bite the bullet, and logically separate it into its own entirely independent multi-repo.

The result of this separation? The deployment pipeline immediately became entirely independent, risk-free, and the build time instantly recovered back to a blazing fast 1 minute. You can definitely read more deeply about my ongoing CI/CD struggles and architectural pivots on my developer blog. In conclusion, here is my final, hard-earned verdict on the Monorepo vs. Multi-repo debate for solo developers: The Return on Investment (ROI) for a monorepo is absolutely maximized when you have exactly between 0 to 10 services that strictly share the exact same technology stack and business domain. It keeps you moving incredibly fast and perfectly consistent. However, the exact moment you introduce a fundamentally different language, framework, or distinct business domain—like irresponsibly mixing Python WebSockets with React web apps—you must immediately separate them into a multi-repo. Do not let the dogmatic obsession of "one repo to rule them all" permanently ruin your development velocity.