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Base64 Decode/Encode.

Decode a message. Encode text or bytes. Copy it into code or download a file.

Inputs stay on your device

01Input

Base64 message

Accepts standard Base64, Base64URL, and Base64 data URLs. Whitespace and omitted padding are supported.

Limit 1 MiB of decoded bytes

02Settings

BASE64 / BYTES

Base64 output alphabet

Include trailing = padding

These settings control Base64 output. Decoding detects either alphabet automatically.

Byte export format

Text when possible. Bytes when needed.

SGVsbG8= decodes to Hello. Text is shown when the bytes are valid UTF-8 without binary control characters; tabs and line breaks are allowed. Detection is a heuristic: a binary file can also contain valid text.

AAECf4D/ decodes to 00 01 02 7F 80 FF. Select HEX, a code snippet, a JSON byte array, binary digits, or a HEX dump. Download .bin preserves every byte, including zero bytes.

Encoding accepts UTF-8 text, HEX bytes, or a file up to 1 MiB. Base64 input is limited to 2 MiB of characters. Incomplete groups, invalid characters, misplaced padding, mixed alphabets, and nonzero unused bits produce an error.

Large previews are bounded; copy and downloads always include all bytes. Other text encodings can be inspected with HEX ↔ String.