Frontend Monolith Decomposition Checklist
A decomposition checklist for breaking up a frontend monolith. It covers coupling mapping, domain boundaries, monorepo structure, enforced dependency rules, ownership, and incremental extraction.
When to Use This Checklist
Use this checklist when a large frontend monolith has become slow to build, hard to change, and risky to release, and you want to decompose it into modular, independently maintainable parts. This may stop short of full micro-frontends; a modular monorepo is often the right first step. Plan the split before moving code.
How to Use This Checklist
Start by mapping reality: the current module structure, shared code, and the coupling hotspots that make changes ripple. Those hotspots reveal where boundaries are missing. Then define domain boundaries deliberately, ideally using domain-driven design, so modules align with how the business and teams actually work.
Choose a structure, commonly a monorepo with packages or enforced module boundaries, and extract shared UI into a versioned design-system package so modules do not each reinvent components. Assign clear ownership per module, since unowned modules drift back toward coupling.
Enforce the boundaries you draw. Use lint or boundaries tooling so modules cannot import across forbidden lines, add tests at module boundaries, and extract incrementally starting with low-risk modules. Record the decision in an architecture decision record so the rationale survives.
What Good Looks Like
Module boundaries align with domains, each module has an owner, and dependency rules are enforced by tooling rather than convention. Shared UI lives in a versioned package, cross-module contracts are defined, and boundary tests catch coupling regressions. Extraction is incremental, and the decision is documented in an ADR.
Common Pitfalls
The biggest pitfall is drawing boundaries on paper but not enforcing them, so coupling creeps back immediately. Teams also over-engineer toward full micro-frontends when a modular monorepo would do, adding runtime complexity they do not need. Leaving modules unowned guarantees drift, and skipping boundary tests hides the very coupling the split was meant to remove.
Related Resources
Pair this with the modular-monolith and micro-frontends practices, design systems for shared UI, team-topologies for ownership, and architecture decision records for rationale. Domain-driven design guides the boundaries.