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.
- 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.