What is a .IDX file?
IDX is the index that sits beside a git .pack file, mapping each object’s SHA-1 to its offset so git can find objects without scanning the whole pack. Created and read by git. The same extension is also widely used for VobSub subtitle indexes and for generic database indexes.
- Did you know
- The index begins with the bytes \377tOc, a deliberately non-text signature so older git versions could tell the version 2 index from the headerless version 1.
- The index lists every object SHA-1 in sorted order, so git finds one by binary search instead of scanning the whole pack.
- A 256-entry fan-out table at the top lets git jump almost straight to the right region of the list from just the first byte of a hash.
- The .idx carries no objects of its own - delete it and git rebuilds it from the .pack with git index-pack.
- What Analyser shows you
- Open git repository internals with no git binary: loose objects (the zlib-compressed blob, tree, commit and tag files under .git/objects), pack files (.pack) and pack indexes (.idx). Inflates and parses each object - showing its type, size and SHA-1, rendering commit and tag messages, listing tree entries, and handing blob contents to the analyser.
- Open a .IDX file
- Drag a .IDX file onto the Analyser home page (or tap to pick one). It opens entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.
- Related formats
- .PACK. See all supported file types.