ToolJovia
Developer

Source Map Explorer

Decode basic version3 source maps and inspect generated/original mapping anchors.

✓ Browser-local processing

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How to use Source Map Explorer

Decode basic version3 source maps and inspect generated/original mapping anchors. A bounded Base64-VLQ reader expands mappings with their cumulative source/name deltas. Lookup uses same-line greatest-lower-bound anchors rather than inventing column interpolation or retrieving source files.

  1. Provide basic source map json, lookup line (1-based), lookup column (0-based), original source index.
  2. Choose the supported mode and run the tool. Review its assumptions and any reported errors.
  3. Copy the result or download a separate output; reset to clear the current form.

Good to know

  • 200,000 JSON characters;100,000 mapping characters;10,000 segments;1,000 sources/names; signed32-bit VLQ values.
  • Basic maps only, no indexed sections or remote/source content fetching. A mapping anchor does not establish original source correctness or executable equivalence.
  • Inputs are processed on this device and are not automatically saved or uploaded.

Common questions

Can several generated positions map to one original position?

Yes. Original lookup returns the supported same-line anchor matches. It does not assume the map is one-to-one or reconstruct removed original code.

Does this change my original input?

No. The tool returns a separate result. Review that output before using it in another application.

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