Duplicate Finder

📖 Tool Introduction

Duplicate Finder is a local comparison tool built for cleaning up photo libraries, download folders and archive disks. Instead of shallow filename matching, which is easy to get wrong, it follows the industry-standard two-step method: first it groups every file by exact byte size, and files of different sizes can never be identical, so they are eliminated immediately; then it computes a SHA-256 digest only for the same-size candidates, and an equal digest means two files are byte-for-byte identical. This keeps the verdict trustworthy while confining the expensive hashing to a small candidate set, so even hundreds of files finish quickly. Once the scan is done, four summary cards across the top report the files scanned, the duplicate groups, the duplicate files and the space reclaimable, keeping one copy per group and treating the rest as redundant. Below, each group of duplicates is rendered as a card with a red left border, listing every member file with its size and a truncated SHA-256 fingerprint so you can follow the evidence and delete the extra copies. The whole report can be copied as text in one click for your records. Because every comparison runs inside the browser, your photos and documents are never uploaded anywhere, which makes the tool safe even for private libraries.

✨ Key Features

• Two-step check: group by size, then SHA-256 the candidates, with zero misjudgement
• Performance friendly: hashing touches only same-size files, so batches stay fast
• Clear summary: scanned count, groups, duplicate files and reclaimable space at a glance
• Clean grouping: red-bordered cards list every member and its size per group
• Fingerprint trace: each group shows its SHA-256 prefix for cross-checking
• Fully offline: comparison happens locally, with zero uploads

📝 How to Use

1. Drop the batch of files you want to tidy onto the dashed area, or multi-select
2. Click Scan now and wait for the grouping and hashing to finish
3. Read the four summary cards to grasp the scale and reclaimable space
4. Inside each red duplicate card, decide which copy to keep
5. Copy the report for your records and delete the extras from your disk

⚠️ Notes

• Delete carefully: the tool only marks duplicates; remove files manually in your file manager
• Same name, different content: files sharing a name but not content are not flagged
• Same size, different content: same-size files with different hashes count as unique
• Huge files: reading and hashing very large files takes time, which is normal
• Privacy: all comparisons run locally in the browser, uploading nothing

🧰 Common use cases

Duplicate files quietly eat disk space: the same photo saved from chat and mail, a document copied to two project folders, a build artifact committed twice. This finder first groups uploaded files by size, since files of different sizes can never be identical, and only computes a cryptographic hash for the few candidates that actually share a size, which keeps the scan fast on large collections. Files landing in the same hash group are presented as a red-bordered cluster, and the top cards summarize total files, duplicate copies, groups and how much space you could reclaim by keeping just one copy of each. The hashing runs in streaming chunks so big videos do not exhaust memory, and the whole analysis happens locally in your browser. The result tells you which copies are byte-identical, not which version you prefer, so review each cluster before deleting: keep the copy you trust most, and treat the manifest as your checklist rather than an automatic cleanup.