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DuoBolt

The app, screen by screen

DuoBolt is one app with two engines and a shared way out. This page walks the whole path once, in order, and points at the page that covers each stop properly.

If you have not run a scan yet, start here instead.


The DuoBolt dashboard: two resumable sessions at the top, each offering Discard or Resume; lifetime totals reading 2,171 scans run, 1,297,696,627 files scanned and 3.0 GiB space reclaimed; a card each for Duplicates — 3.2 GiB still wasted against 3.0 GiB reclaimed — and Similars — 4,254 to review against 1,410 culled; and a table of recent scans underneath giving when, folders, what was scanned, how long it took, the groups found and what they waste.

Two engines, and the choice between them is the choice of question:

Find Duplicates

Files that are byte-for-byte identical, verified by a full BLAKE3 hash. How matching works

Recent scans are listed here, and any of them can be run again with the exact setup it used.

Above them sits Continue where you left off, and it only appears when there is something to continue — one card per engine, naming the folders and what the scan found, with Discard and Resume on it. What resuming does is covered under progress.

The rest of the dashboard is counters rather than controls: Lifetime totals every scan you have ever run, and By feature splits the two engines — what is still wasted against what you have already reclaimed on the duplicates side, how many photos are waiting to be reviewed on the other.


Add folders — as many as you like, on any volume — and adjust Scan parameters if the defaults do not fit. The info card underneath summarizes the setup, and mentions only what deviates from the defaults, so a quiet card means a standard scan.


Duplicates runs Scan → Prehash → Hash → Finalize; Similars fingerprints and then groups. Both report live counts, and both can be left alone — if the app closes with an open result, the session is saved and offered back on the next launch, selections and all.


Where the work happens. The two screens differ because the questions differ — duplicates is a list ordered by recoverable space, similars is a grid of groups you look at.


Marking is not removing. Everything goes through Review Selection, which counts the batch, warns where a file would have no copy left behind, and then offers four ways out.


Every scan and every operation is written down, and most operations can be undone from a surviving copy — verified by content hash, months later, long after the OS Trash is gone.


A folder was skipped — check that the OS granted DuoBolt access, under macOS Privacy & Security or Windows permissions.

Everything is slow — USB 2.0 enclosures and network mounts are simply slower. Antivirus scanning every read is the other usual culprit; allow-list DuoBolt during scans.

HEIC or AVIF show no preview on Windows — install the two free Microsoft Store extensions. The files are still found, hashed and grouped without them; see installation.

Fewer duplicates than expected — the default scan starts at 64 KiB and skips system and hidden files. What that excludes.