Base64•100% Client-Side

Base64 Decoder Online

Decode Base64 encoded strings back to clean plain text format instantly. Supports standard and URL-safe Base64 inputs with full UTF-8 Unicode character support client-side.Reference Spec: IETF RFC 4648 (Base64 encoding standards)→

Base64 Encoded Input
Decoded Plain Text

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Frequently Asked Questions (Base64 Decoder)

What is Base64 Decoding?

Base64 decoding is the reverse of encoding; it translates a base64-encoded ASCII string back into the original raw text or binary data. The input string must only contain standard base64 characters (A-Z, a-z, 0-9, +, /, and padding =).

How does this decoder handle URL-safe base64 strings?

Our tool automatically detects URL-safe Base64 strings. It replaces '-' with '+' and '_' with '/', and appends the necessary padding '=' characters dynamically before performing decoding.

What happens if I paste invalid Base64?

If the input contains invalid characters (like spaces or symbols outside the base64 character set) or is corrupted, the tool displays a warning alert notifying you of the syntax error.

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