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File MIME Type Inspector - local file signature and metadata check

Upload files and inspect filename, size, browser MIME type, extension, and magic-byte signature locally.

  • Runs locally
  • Category Format Converter
  • 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

File MIME Type Inspector helps you understand what a file appears to be before you upload, import, or hand it to another system. Drop one file or a batch and the tool reports filename, byte size, browser-reported MIME type, extension, first bytes in hex, and common magic-byte signatures such as PNG, JPEG, PDF, ZIP, GIF, gzip, RAR, and SVG. It is useful when a vendor export has the wrong extension, a browser upload rejects a file, a support ticket includes mystery attachments, or an engineering team needs a quick local evidence table without sending files to a server.

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
Format Converter · Developer
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 File MIME Type Inspector 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 Local File Workbench Triage a mixed batch locally for file type mismatches, duplicate candidates, metadata privacy, archive risks, and next-step tools. Open
  2. 2 File Hash Calculator Compute SHA-1, SHA-256, SHA-384, or SHA-512 hashes for uploaded files entirely in the browser. Open
  3. 3 File Checksum Compare Paste an expected checksum, upload a file, and verify SHA digest matches locally before installing or sharing. Open

Real-world use cases

  • Diagnose upload rejection

    Compare extension, browser MIME type, and magic bytes before deciding why a system rejects a file.

  • Summarize mystery attachments

    Produce a CSV evidence table for support or compliance review without uploading the attachments.

Common pitfalls

  • Magic-byte checks are signatures, not malware scanning.

  • Some text formats share weak signatures and require deeper content inspection.

Privacy

File inspection runs locally in the browser. The report may still reveal filenames or sizes, so review before sharing it.

FAQ

Tool combos

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Made by Toolora · 100% client-side · Updated 2026-06-13