Source map validator

Validate source maps before minified errors reach production

Paste a minified bundle footer and source map JSON to catch missing mappings, source lists, sourceMappingURL mismatches, and sourcesContent gaps.

Validation runs locally in your browser. Bundle snippets and source map JSON are not uploaded or stored.

Free browser tool

Check bundle and source map

ready

This source map shape is ready for production error symbolication.

Source Map v3pass

The map declares version 3.

Sourcespass

At least one original source path is present.

Mappingspass

Mappings are present for generated-to-original frame lookup.

Names arraypass

The names array is present, even if it is empty.

sourcesContentpass

Original source content is embedded for each source path.

Bundle footerpass

Found sourceMappingURL=checkout.js.map.

File linkagepass

The bundle footer and source map file field line up.

Checks

Useful enough for the immediate debugging job.

Each utility is product-adjacent by design: it solves a concrete setup or debugging problem, then links to the Squasher workflow that monitors it continuously.

Checks Source Map v3 shape, sources, mappings, names, and sourcesContent alignment.

Compares the bundle sourceMappingURL footer with the source map file field when present.

Explains common mistakes that make production stack traces unreadable.

2026-05-06

Keep source maps connected to production errors.

Squasher uses source maps, releases, and stack traces together so minified JavaScript errors remain fixable after deploy.