Editing an existing archive

Most Mac archive utilities only let you create new archives or extract old ones. If you want to add a file to an existing .zip, the conventional workflow is: extract everything to a folder, drop the new file in, re-zip the whole folder, delete the original.

Purrchiver lets you skip all of that. Open the archive, click Edit, add or remove entries, save. Done.

This is one of Purrchiver’s biggest features and the reason a lot of people switch.

Browse mode vs. Edit mode

When you open an archive in Purrchiver, you land in Browse mode — read-only, safe to inspect or extract from without changing the file.

To make changes:

1. Click the Edit button (pencil icon) in the toolbar, or press ⌘E.
2. The window switches into Edit mode — title shows Editing <archive name>, the right pane now accepts drops, and selected rows show a trailing − button to remove them.
3. The toolbar’s Create Archive button becomes your save action.

Making changes

In Edit mode:

• Add files — drag from Finder or from the left filesystem pane into the right pane.
• Remove entries — select rows in the right pane and click the trailing − button. Multi-select with ⌘-click or shift-click.

Changes accumulate in memory. The archive on disk isn’t touched yet.

Saving — the Create Archive flow

Click Create Archive (or press the keyboard shortcut). Purrchiver opens a standard macOS Save dialog pre-filled with your source archive’s name and location:

• Click Save with the pre-filled name → overwrites the original. The save is atomic — Purrchiver writes the new archive to a hidden sibling file first, then swaps it into place as a single filesystem operation. If the write fails partway through (power loss, force quit, full disk, verification failure), the original archive on disk is untouched and the partial file is cleaned up. Either you see the new archive in Finder, or you see your original — never an intermediate state.
• Change the name or pick a different folder → saves a copy. The original is untouched.

Format conversion on save

The format picker next to Create Archive defaults to your source archive’s format, but you can pick a different one. Example workflow:

1. Open a .zip
2. Click Edit (⌘E)
3. Optionally add/remove entries
4. Change the format picker to 7z
5. Click Create Archive

Result: a new .7z archive containing the same (modified) entries. This is the cleanest way to convert an archive from one format to another — no separate “convert” command needed.

How saving works under the hood

Purrchiver streams each kept entry’s bytes directly from your source archive into the new archive — no intermediate extract-to-disk step.

That means editing a 5 GB archive doesn’t require 10 GB of free disk space. The largest single entry being copied at any moment is the only meaningful temporary disk usage.

After the write completes, Purrchiver verifies the new archive (re-reads every entry, confirms passwords if encrypted) per your verify-after-creation setting in Settings. Verify runs against the temporary output, before the atomic swap into place, so a verification failure aborts the swap and leaves your original archive untouched on disk.

The atomic-save flow uses FileManager.replaceItem under the hood, which on macOS becomes a single same-volume renameat/F_REPLACEFILE call when the new file is in the same folder as the destination — which it always is, by design. Cross-volume swaps would fall back to a non-atomic copy + delete, so Purrchiver always writes the temp file into the destination’s own directory.

Encrypted archives in Edit mode

Open the archive and enter its password. Click Edit. Purrchiver keeps the password in memory for the duration of the Edit session so it can read the source archive’s bytes when you save.

When you save:

• Keep the password unchanged → the fast-path Save (⌘S) reuses the active preset, which carries the same password as the source archive.
• Change the password (or add/remove encryption) → use the Create Archive sheet directly instead of the fast-path Save. Set the format to an encrypted variant (e.g. ZIP + AES-256 or 7z + AES-256), enter the new password, and create. The fast-path ⌘S in Edit mode does not surface password fields.

See Encrypted archives for password best practices.

Read-only formats

The Edit button is disabled for formats Purrchiver can’t write or rewrite cleanly. The Edit button shows a tooltip explaining why on hover.

For any read-only format, the workflow is: extract everything, modify the files, then create a new archive (probably as ZIP or 7z) with Compress.

v1.0 Edit limitations

These features are not yet supported in the current Edit mode. Planned for future releases:

• Rename entries — to rename, extract the entry, rename the file, and add it back as a fresh entry (or recompress the whole archive).
• Reorder entries — entries from the source archive appear in their original order; newly-added files appear at the end.
• Symbolic links in the source archive — currently skipped during the Edit save. The rewritten archive omits them.
• Tar-family editing (.tar, .tar.gz, .tar.bz2, .tar.xz, .tar.zst, .tar.lz) — Edit button is disabled while we refine the round-trip detection logic. To modify a tar, extract → modify → recompress.

We’re tracking these for v1.1. If any one of them blocks a workflow you care about, please email corey@purrchiver.app — user signal informs the priority order.

Closing with unsaved changes

If you’ve made changes in Edit mode and try to close the window without saving, Purrchiver shows the standard macOS sheet:

Save your changes to archive name?

Your changes will be lost if you don’t save them. The original archive on disk hasn’t been modified yet.

[Don’t Save] · [Cancel]

Cancel returns to the window so you can save. Don’t Save discards your edits and closes — the file on disk is left exactly as you opened it.

Tips

• Format conversion is free. If you’ve been meaning to migrate a .zip to .7z for better compression, Edit + change-format-on-save is the cleanest path.
• Editing a solid 7z rewrites the whole archive. Solid 7z compresses all entries together; any change requires re-emitting the whole stream. Purrchiver shows a one-time warning for these.
• Don’t edit huge archives over a network volume. The streaming rewrite reads and writes a lot of bytes. Local SSD = fast; SMB or iCloud Drive = slow + risky.

Related

• Opening an archive
• Encrypted archives — change password on save
• Creating a new archive — same Create Archive sheet
• Format support — which formats can be edited
• Keyboard shortcuts — ⌘E and friends