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Image Format Detector

Detect the real format of an image file by inspecting its magic bytes. Warns if extension mismatches the actual format. Fully private.

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Image Format Detector

Inspect the actual format of any image file by reading its magic bytes — the first few bytes that uniquely identify each format. The browser-side detector recognizes PNG, JPEG, GIF, WebP, BMP, TIFF, HEIC, AVIF, SVG, and ICO and warns when the file extension lies about the real content.

Why magic bytes

File extensions are easy to rename and untrustworthy. Magic bytes — also called file signatures — are embedded in the file header and reliably identify the real format. Servers, security scanners, and content moderation systems rely on them.

Use cases

Verify suspicious image downloads
Detect renamed files (e.g., .jpg that's actually PNG)
Pre-flight checks before processing
Forensic and incident-response workflows
Debugging image upload pipelines

All detection is done locally — nothing is uploaded.