Source Map Decoder

Source map JSON

Paste the raw JSON, or a data:application/json;base64,... URL from a //# sourceMappingURL= comment. The full file (sources included) stays in your browser.

Generated → Original lookup

Enter a 1-based line and 0-based column from your minified bundle (e.g. from a stack trace) to find the corresponding original source location.

Generated line (1-based)

Generated column (0-based)

Decoded mappings 0 segments

Show all

Gen L:C	Source	Orig L:C	Name

Original source browser

About Source Map v3

Format: JSON with version: 3, sources, optional sourcesContent, names, and the giant mappings string.
Mappings: lines separated by ;, segments by ,. Each segment is 1, 4, or 5 Base64 VLQ values: generated column, source index, original line, original column, and (optionally) name index — each value relative to the previous segment.
VLQ: each value is split into 5-bit chunks, with a continuation bit (bit 5) and a sign bit (bit 0 of the first chunk). The 6-bit chunks map to A-Za-z0-9+/ via Base64.
Reverse lookup uses binary search over the segments for the target line.
Inline maps are usually data:application/json;charset=utf-8;base64,... appended to bundles. The decoder here strips the prefix and decodes automatically.