Base64 Decode — Know What It Is Before You Decode It

Paste a base64 string. This tool identifies the format first — PNG, JPEG, PDF, ZIP, GZIP, audio, JSON, plain text, base64url or JWT — then decodes it. Images get a preview.

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Try: PNG JPEG PDF ZIP base64url JWT not base64
Paste a string above — the format verdict appears here before anything is decoded.

All 20 signatures this detector checks

Every row below was verified by generating a real sample, encoding it, decoding it back and reading the actual magic bytes. Detection runs in three layers: shape first, then the base64 prefix, then the decoded magic bytes.

Formatbase64 prefixDecoded magic bytes