Your npm Package Is Leaking Source Code (And You Probably Don't Know It)

So here's a fun scenario: you spend weeks building a polished CLI tool, carefully minify and bundle your TypeScript into a neat little package, publish it to npm... and then someone casually reconstructs your entire original source code in about thirty seconds. This isn't hypothetical. It happened publicly in early 2025 when a well-known AI company shipped their CLI tool to npm with source map files included. The community had the full original TypeScript source, system prompts, and internal logic extracted before anyone on the team noticed. Let's talk about why this happens and how to make sure it never happens to you. What Are Source Maps and Why Are They Dangerous? Source maps are JSON files (usually .js.map ) that map your minified or bundled output back to the original source code. They exist so you can debug production builds in browser DevTools or Node.js without staring at a wall of mangled variable names. Here's the thing most people miss: source maps don't just contain mappin