Skip to main content

Duplicate File Finder - local exact duplicate detection

Upload a batch and find exact duplicate files by SHA hash locally, with a Markdown cleanup report.

  • Runs locally
  • Category Encoding & Crypto
  • Best for Checking file type, size, metadata, and obvious mismatch signals before sharing.
Nothing is uploaded. Up to 50 files / 100 MB per batch; text and Base64 tools use lower browser-memory limits.
Output

What this tool does

Duplicate File Finder groups uploaded files by cryptographic hash so you can spot exact duplicates before archiving, sharing, renaming, or uploading a folder. It reads each file in the browser, computes a SHA digest, and reports duplicate groups with filenames and sizes. This is useful for photo exports, contract copies, dataset samples, vendor folders, and support attachments where duplicate names are not reliable. The tool intentionally finds byte-for-byte duplicates, not visually similar images or near-duplicate documents.

Tool details

Input
Files + Text + Numbers
The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output
Live result + Copy + Download
The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy
Browser-side processing
The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share
Shareable URL state
Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget
Initial JS <= 34 KB
No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit
Encoding & Crypto · Operations
Category and role tags drive related tools, internal links, and quick fit checks.

How to use

  1. 1. Input

    Paste or drop your content into the tool panel.

  2. 2. Process

    Click the button. All processing is local in your browser.

  3. 3. Copy / Download

    Copy the result or download to disk in one click.

How Duplicate File Finder fits into your work

Use it before upload, handoff, archive, support review, or any moment where a file needs one local check before it leaves your machine.

File jobs

  • Checking file type, size, metadata, and obvious mismatch signals before sharing.
  • Preparing mixed folders for upload, archive, intake, or review.
  • Keeping sensitive files in the browser instead of sending them to an account-based service.

File checks

  • Do not treat the extension alone as proof of the real file type.
  • Review metadata before a file goes to customers, vendors, or a public page.
  • Keep the original file until the copied, converted, or exported result is verified.

Good next steps

These links move the current task into a more complete workflow.

  1. 1 File Hash Calculator Compute SHA-1, SHA-256, SHA-384, or SHA-512 hashes for uploaded files entirely in the browser. Open
  2. 2 File MIME Type Inspector Upload files and inspect filename, size, browser MIME type, extension, and magic-byte signature locally. Open
  3. 3 Batch File Rename Planner Upload a batch, generate safe new filenames with sequence numbers and case rules, then export a CSV plan. Open

Real-world use cases

  • Clean up a handoff folder

    Select candidate files, find exact duplicates, then decide which copies to delete outside the browser.

  • Verify repeated exports

    Confirm two files are truly identical before keeping one archive copy.

Common pitfalls

  • Same filename does not mean duplicate; this tool compares file bytes.

  • Similar images exported at different quality levels will not match.

Privacy

Duplicate detection runs locally and does not delete anything. Use the report to decide cleanup actions yourself.

FAQ

Tool combos

Folks in your role tend to reach for these alongside this tool.

Browse all tools for this role
Made by Toolora · 100% client-side · Updated 2026-06-14