Nx — Smart Monorepos and Fast CI for JavaScript and Beyond

What it is

Nx is a build system and monorepo management tool with first-class support for JavaScript, TypeScript, Go, Python, Java, and more. It provides computation caching, affected-only commands, task orchestration with dependency graphs, and distributed execution across CI agents.

It targets development teams managing monorepos of any size, from small multi-package repositories to large enterprise codebases with hundreds of projects. Nx works as a standalone tool or integrates with existing package managers and build tools.

How it saves time or tokens

Nx caches task outputs (builds, tests, lints) locally and remotely. If code has not changed, Nx replays the cached result instead of re-running the task. The 'affected' command identifies which projects are impacted by a code change and only runs tasks for those projects. These two features together can reduce CI times by 50-90% on large monorepos.

How to use

1. Install Nx: npx create-nx-workspace@latest for a new workspace, or npx nx init to add Nx to an existing repo.
2. Define projects and their targets in project.json or package.json files.
3. Run tasks with npx nx run <project>:<target> or use npx nx affected --target=test to only test changed projects.

Example

# Create a new Nx workspace
npx create-nx-workspace@latest myorg --preset=ts

# Run tests only for affected projects
npx nx affected --target=test --base=main

# Build all projects with caching
npx nx run-many --target=build --all

# Visualize the dependency graph
npx nx graph

Related on TokRepo

• Coding tools — Development tools and frameworks
• Automation tools — Build and workflow automation

Common pitfalls

• Nx cache invalidation depends on correct input/output configuration. Misconfigured task inputs cause stale cache hits that produce incorrect results.
• Adding Nx to an existing large repo requires upfront effort to define project boundaries and dependency relationships correctly.
• Remote caching (Nx Cloud) requires a connection to Nx's cloud service or a self-hosted cache server. Without remote caching, CI agents cannot share cache entries.