1. 01In extract mode choose an archive and enter the password if it needs one.
2. 02Look down the entry list first, then download a single file, or unpack everything and repack it as a ZIP.
3. 03In create mode add files and produce a ZIP to download.

Give it backup.7z and it lists the sanitised entry paths; “Extract all” repacks the results into a ZIP and downloads that, rather than writing anything straight into the original folders on your computer.

• Archives above roughly 1.5 GB raise a browser memory warning.
• The implementation pre-checks the entry count, the declared unpacked total and the compression ratio; once unpacking starts it verifies the real sizes again, and hitting a limit aborts the run and releases the data and the worker.
• ../, absolute paths, drive letters and illegal path characters are cleaned into safe relative paths, so no traversal meaning reaches the output ZIP.
• A wrong password, a damaged file, encrypted file names or an unsupported compression feature can all make parsing fail.
• Everything runs inside the browser's available memory, which is not the same as the full capability of desktop 7-Zip or WinRAR.

Archive contents and passwords are handled in the browser and never uploaded. Still, handle sensitive archives on a machine you trust, and remember that the new ZIP you download lands wherever your browser saves downloads.