How to browser zip repair vs zip -ff, 7-zip and diskinternals
- Step 1Compare recovery method — All four scan for local file headers and ignore the corrupt central directory. JAD does this with fflate in WebAssembly; zip -FF and 7-Zip do it natively; DiskInternals wraps it in a wizard. The salvageable set is broadly the same.
- Step 2Compare privacy — JAD runs in your browser tab — the file never uploads. The three CLIs/desktop apps also run locally. The browser path additionally needs no install or admin rights, which matters on managed machines.
- Step 3Compare ceiling — JAD caps each job at 500 MB (Pro) or 2 GB (Pro-Media / Developer) and holds the whole file in RAM. zip -FF and 7-Zip stream from disk and handle much larger archives.
- Step 4Compare encryption handling — JAD skips encrypted entries (no password field). 7-Zip and zip can carry a password forward; for password testing on JAD use Archive Password Tester separately.
- Step 5Compare output fidelity — JAD rebuilds with deflate level 6 and byte-scan entry order. zip -FF preserves more original metadata. Extracted contents match in all cases; the container differs.
- Step 6Pick per job — Reach for the browser tool for a quick private recovery; reach for a CLI for batch repair, CI, or multi-GB archives.
Feature comparison
JAD's behavior is from the repairZip handler; CLI behavior reflects standard documented modes.
| Capability | JAD ZIP Repair | zip -FF | 7-Zip (keep broken) | DiskInternals |
|---|---|---|---|---|
| Install required | No (browser) | Yes (Info-ZIP) | Yes | Yes (Windows) |
| Uploads your file | No | No (local) | No (local) | No (local) |
| Scans local headers, skips directory | Yes | Yes | Yes | Yes |
| Recovers encrypted entries | No (skipped) | With password | With password | Limited |
| Scriptable / CI | No (UI only) | Yes | Yes (7z CLI) | No (GUI) |
| Practical size ceiling | 500 MB / 2 GB by tier | Disk-bound | Disk-bound | Disk-bound |
| Output container | Fresh ZIP, deflate 6 | Rebuilt ZIP | Extracted files | Rebuilt ZIP |
When to use which
Decision matrix by job shape.
| Situation | Best choice | Reason |
|---|---|---|
| One-off recovery, sensitive file | JAD ZIP Repair | No upload, no install, runs in the tab |
| No admin rights on the machine | JAD ZIP Repair | Nothing to install |
| Archive over 2 GB | zip -FF or 7-Zip | JAD holds the whole file in RAM |
| Batch of hundreds of corrupt ZIPs | 7z / zip in a script | JAD is single-file, UI-driven |
| Encrypted entries to recover | 7-Zip with password | JAD skips encrypted entries |
| Need a clean standard ZIP fast | JAD ZIP Repair | Outputs a ready-to-use ZIP plus a recovery report |
Cookbook
The same corrupt files run through JAD versus the CLIs, showing where the outcomes match and where they diverge.
Truncated download — JAD vs zip -FF
A 30 MB ZIP cut off mid-transfer. Both tools recover the same complete entries.
JAD: drop file -> Process
Attempts 188 / Recovered 187 / 99%
-> data-repaired.zip
CLI: zip -FF data.zip --out data-fixed.zip
-> 187 entries reconstructed
Same survivors; JAD adds a recovery-rate report, CLI is scriptable.Encrypted entries — divergence
An archive with password-protected files. JAD skips them; 7-Zip can carry the password.
JAD: Attempts 40 / Recovered 33 / 82% (7 encrypted -> skipped) 7-Zip: 7z x broken.zip -pSECRET (recovers encrypted ones too) Use JAD for the plain files; use 7-Zip when you hold the password.
Wrong format dropped in
A RAR with a .zip extension. JAD reports no headers; 7-Zip detects the real format.
JAD: "No recoverable local file headers found..."
-> run /archive-tools/auto-format-detector
7-Zip: opens it as RAR directly (format auto-detected)
Use Auto Format Detector first to avoid this on JAD.Multi-GB archive
A 6 GB corrupt ZIP exceeds JAD's tier ceiling and browser RAM.
JAD: tier-limit error (2 GB max on Pro-Media / Developer) CLI: zip -FF huge.zip --out huge-fixed.zip (streams from disk) For multi-GB archives a CLI is the right tool.
Clean handoff after browser repair
Where the browser tool genuinely wins: a quick recovery on a machine with no software install rights.
Locked-down laptop, no admin: JAD ZIP Repair -> report-repaired.zip /archive-tools/archive-integrity-tester -> CRCs pass No install, no upload, done in the browser.
Edge cases and what actually happens
Encrypted entries
JAD skips; CLI can recoverJAD skips entries with the encryption flag set. zip and 7-Zip accept a password to recover them. If your survivors are encrypted, a CLI is the better fit.
Archive over 2 GB
Error: tier limitJAD's hard ceiling is 2 GB (Pro-Media / Developer) and it holds the file in RAM. zip -FF and 7-Zip stream from disk and have no such limit.
Non-ZIP file
Error: no headersJAD only understands ZIP local headers and errors on RAR/7z/TAR. 7-Zip auto-detects many formats. Confirm format with Auto Format Detector before using JAD.
Batch of many files
Not supportedJAD's repair tool is single-file and UI-driven. For hundreds of corrupt archives, script a CLI loop instead.
Metadata fidelity
By designJAD rebuilds with deflate level 6 and byte-scan entry order. CLIs like zip -FF preserve more original ordering and metadata. Extracted contents match in all cases.
Damaged payload bytes
Skipped everywhereNo tool can reconstruct genuinely corrupt compressed data. JAD skips and continues; the CLIs report the same entries as unrecoverable.
No install permitted
JAD winsOn a managed machine where you cannot install Info-ZIP or 7-Zip, the browser tool is often the only option that works without admin rights.
Reproducible / scripted runs
CLI winsCI pipelines and repeatable batch jobs need a CLI. JAD has no programmatic API for archive tools (apiAvailable is false).
Frequently asked questions
Do JAD and zip -FF use the same recovery method?
Effectively yes. Both ignore the corrupt central directory and scan for surviving local file headers, then rebuild a clean archive. The implementations differ but the salvageable set is broadly the same.
Is the browser tool slower than a CLI?
For files under a few hundred MB the browser scan is fast — fflate is highly optimized. CLIs pull ahead on multi-GB archives because they stream from disk rather than holding the file in RAM.
Which is more private?
Both are private — nothing uploads in either case. The browser tool adds the benefit of needing no install or admin rights, which matters on locked-down machines.
Can the browser tool recover encrypted entries like 7-Zip can?
No. JAD skips encrypted entries because it has no password field. 7-Zip and zip can carry a password forward. For password work on JAD, the Archive Password Tester is a separate tool.
Are the outputs interchangeable?
Yes. JAD produces a standard ZIP you can open with unzip, 7-Zip, or any consumer. There is no JAD-specific wrapper, so the repaired file drops straight into any workflow.
When should I prefer the CLI?
Files over 2 GB, scripted or CI pipelines, batches of many archives, and cases where you need to recover encrypted entries with a known password.
When should I prefer the browser tool?
One-off recoveries, sensitive files you do not want on a server, machines where you cannot install software, and quick jobs where the recovery report saves you time.
Does JAD preserve original entry order like zip -FF?
No. JAD lists entries in byte-scan order (their offset in the file). zip -FF tends to preserve more of the original ordering. Extracted file contents are identical either way.
Can I automate JAD's repair in CI?
Not via an API — archive tools have no public endpoint (apiAvailable is false). Paid tiers can route through a local headless-browser runner, but for true CI automation a CLI is more appropriate.
Does DiskInternals do anything JAD cannot?
It adds a Windows wizard and some preview features, but the underlying header scan is the same. For a quick cross-platform, no-install recovery the browser tool is comparable.
What about files just over the limit?
If a file is just past 500 MB on Pro, upgrade to Pro-Media or Developer (2 GB) or use a CLI. There is no streaming repair mode in the browser tool.
Can I verify a CLI-repaired file in JAD?
Yes — run any repaired ZIP through Archive Integrity Tester or Checksum Generator regardless of which tool produced it. JAD's analysis tools work on standard archives.
Privacy first
Every JAD Archive tool runs entirely in your browser using fflate, @zip.js/zip.js, and the libarchive WASM bridge. Your archives never leave your device — verified by zero outbound network requests during processing.