An exact duplicate file finder, with zero guessing
DuoBolt only flags two files as duplicates when their contents are byte-for-byte identical, proven by a full BLAKE3 hash. No name patterns, no size-only matches, no fuzzy logic — every duplicate group is mathematically guaranteed.
Compare file contents, not metadata
Most duplicate finders take shortcuts: same name and similar size, partial CRC32, or a quick perceptual hash on photos. Those shortcuts are fast — and they routinely produce false positives that nuke the wrong file. DuoBolt picks a different default: every candidate is fully read and hashed with BLAKE3, so a duplicate group is only ever a set of files with identical content.
Full BLAKE3 hashes
Every candidate file is fully hashed with BLAKE3, the modern parallel cryptographic hash. Two files are reported as duplicates only if their hashes match — i.e., if their contents are byte-for-byte identical.
No name or size shortcuts
DuoBolt never declares a match based on file name, modification time, or size alone. Those fields are surfaced in the UI for context but they are not used to decide what is a duplicate.
Symlink and hardlink aware
Hardlinks and symlinks are detected and collapsed so a single inode never inflates a duplicate group. You see real, recoverable duplicates — not the same file counted twice.
Identical results, two interfaces
The Desktop app and the CLI use the same engine, the same hashing logic, and the same grouping algorithm — so a scan on macOS, Windows, or Linux returns the same set of duplicates.
How an exact match is proven
Four stages between dropping a folder onto DuoBolt and seeing a confirmed duplicate group.
- Step
Group by size
Files of different sizes can never be byte-for-byte equal, so DuoBolt buckets them by size first. Singletons are dropped immediately.
- Step
Head+tail prehash
For each remaining group, BLAKE3 hashes the first and last N KiB. Any file whose prehash is unique is removed from consideration before the engine touches the rest of its bytes.
- Step
Full-content hash
Survivors are fully streamed and hashed with multi-core BLAKE3. Files with identical full hashes are guaranteed to be identical in content.
- Step
Stable grouping
Confirmed duplicates are grouped, sorted, and surfaced. Symlinks and hardlinks are collapsed so the result reflects real recoverable space.
Exact duplicate finder FAQ
- What does “exact” mean in DuoBolt?
- Two files are exact duplicates only when they are byte-for-byte identical, as proven by matching full BLAKE3 hashes. There is no fuzzy, perceptual, or AI-style matching anywhere in the engine.
- Why does DuoBolt sometimes find fewer duplicates than other tools?
- Because it avoids false positives. Tools that match by name, size, or partial checksum will report files that look similar but differ in content. DuoBolt only reports a match when full BLAKE3 hashes agree, so its output is conservative by design.
- How small is the chance of a hash collision?
- BLAKE3 is a cryptographic hash with 256 bits of output and 128-bit collision resistance. The probability of a collision on any realistic dataset is effectively zero — far smaller than the probability of disk read errors or hardware failure during the scan itself.
- Are the Desktop and CLI results identical?
- Yes. Both share the exact same engine, hashing logic, ignore rules, and grouping. With equivalent settings the duplicate groups returned are identical.
- Does DuoBolt work fully offline?
- Yes. Scanning, hashing, and review all happen locally on your machine. No file content ever leaves the computer.
Keep exploring
Why BLAKE3
How BLAKE3's tree structure, SIMD kernels, and cryptographic guarantees make it the right hash for a duplicate finder.
Read moreCore concepts
Prehashing, grouping, symlink rules, and the assumptions behind every scan.
Read morePerformance benchmarks
How exact-match scanning still beats fuzzy tools on real terabyte-scale datasets.
Read more