Unpack production JavaScript source maps, explore reconstructed source directories, inspect original unminified files, and download as ZIP.
Source recovery depends on what the map contains. A map can name a file without embedding its original source text.
The tool reads sourcesContent rather than inventing code from the minified bundle. Use the map from the same build when investigating a production issue.
Names and mapping data do not contain the complete original file. Obtain the corresponding build sources or a map with embedded content to recover that text.
The explorer does not reproduce a complete runnable project from missing dependencies, configuration, or source files.
The Free Source Map Un-Minifier & Explorer is a browser-based reverse-engineering utility designed to reconstruct original, human-readable source code hierarchies from production JavaScript bundles and source map files. Modern build pipelines using Webpack, Vite, esbuild, and Rollup compress, minify, and mangle variables to optimize web performance, making production bug triage notoriously difficult without proper source map correlation. Our tool enables engineers to inspect, navigate, and restore original TypeScript, JSX, and JavaScript trees directly in the browser.
Unlike command-line reverse engineering tools that require Node.js installs or cloud decompilers that capture proprietary intellectual property, our explorer parses V3 source map structures entirely in local client memory. It decodes standard Variable-Length Quantity (VLQ) mappings and extracts embedded sourcesContent strings to restore the exact original folder hierarchy and unminified files. Engineers can audit production security leaks, verify build tree hygiene, or reconstruct lost frontend source repositories with zero risk of exposure.
Navigate an interactive virtual directory tree displaying nested source folders, inspect individual original files with line-numbered syntax formatting, and search across thousands of files for specific modules. When your inspection is complete, export the entire reconstructed codebase as a structured ZIP archive in a single click using in-memory compression.
Drag and drop your .js.map file, a bundle with inline data URI mappings, or provide both the minified .js and corresponding .map file.
Explore the virtual folder hierarchy representing original project source files, node_modules dependencies, and build configuration assets.
Select any source file from the tree to preview unminified TypeScript, JSX, or CSS code with syntax highlighting, search, and line numbers.
Click Export All Sources as ZIP to generate a clean archive recreating the entire project directory tree for local review and recovery.
Fully decodes VLQ mappings and embedded sourcesContent data from modern bundlers including Vite, Webpack, esbuild, and Next.js.
Organizes hundreds of unpacked files into an intuitive, collapsible directory tree mirroring original repository folder architectures.
Instant keyword filtering across all project paths with a clean code view featuring line numbering and formatted indentation.
Bundles all reconstructed source files and directories into a standardized ZIP file using in-memory client-side compression.
Source Map V3 files map minified bundle locations to original source trees. If the source map includes sourcesContent, full original source code can be restored without external build artifacts.
Browse the original files embedded in the map that corresponds to a deployed build.
Check which paths and source text your own published map contains before deciding how to distribute future maps.
| Source Map V3 Field | Format & Schema Type | Engineering & Reverse-Engineering Role |
|---|---|---|
| version | Integer (always 3) | Specifies adherence to the Google Source Map V3 standard specification |
| sources | Array of file path strings | Relative path hierarchy of all original source files compiled into bundle |
| sourcesContent | Array of string contents | Full embedded text of original unminified source files (enables 100% recovery) |
| mappings | Base64-VLQ encoded string | Line and column mapping coordinates between minified and source files |
| names | Array of identifier strings | Original variable and function names before minification and mangling |
| sourceRoot | String prefix path | Optional URL or filesystem root prepended to all paths in sources array |
A source map is a JSON file conforming to the Source Map V3 specification that maps positions in a minified production file back to corresponding lines and columns in original source files. Many source maps also embed the entire original source text within a sourcesContent array, allowing complete file restoration.
An internet connection is required to open tools and refresh a temporary session. Processing stays on your device; the handshake sends a random challenge, not files or text inputs. Libraries, fonts or models may download. Local processing cannot remove risks from an untrusted device or extension.
When a source map lacks sourcesContent, the tool maps identifiers and positions against the accompanying minified JS file using VLQ decoding, though embedded sources provide the highest fidelity recovery.
If your JavaScript file ends with //# sourceMappingURL=data:application/json;base64,..., paste that data string or upload the JS bundle directly; the tool automatically extracts and decodes the inline base64 map.
