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ZIP inspector & builder

List what is inside a ZIP before you open it — sizes, ratios, traversal names, nested archives — extract single entries, or build a new archive. fflate runs in a worker; caps are checked against declared sizes before inflating and re-checked against the inflated bytes after.

ZIP in

The signature is read from the bytes — a renamed file that is not a ZIP is refused, not guessed at.

zip files up to 256 MB · entries capped at 10,000
Build a ZIP
up to 2,000 files · deterministic mtime (byte-identical for identical input)
What this tool does not do
  • No tar, 7z, RAR, or encrypted archives — fflate owns ZIP only, and password-protected entries are refused, not guessed at.
  • Nested archives are flagged and never extracted recursively; traversal names are refused, never "cleaned".
  • Nothing is uploaded — the archive is read in a worker in your tab.
Nothing in yet

Paste, drop, or type to begin. Everything stays on this device.

drop a .zip to list it, or pick files to build one