UTF-8 Base64 converter

Encode Unicode text as RFC 4648 Base64 or strictly decode Base64 back to UTF-8 with explicit padding rules.

Your input

Outputs are cleared when the input changes.

Result

Enter your data or use the example, then run the tool.

Worked example

foo encodes to Zm9v and decodes back to foo.

Chinese text and emoji round-trip; invalid alphabet, padding, pad bits or non-UTF-8 decoded bytes are rejected.

Method

Encode text with TextEncoder, then map bytes to the selected standard or URL-safe alphabet.

Decode only after alphabet, length, padding and unused-bit validation, using fatal UTF-8 decoding.

Limits

UTF-8 bytes are limited to 5 MiB; Base64 input allows the corresponding encoded length. Lone surrogates are rejected.

Missing padding and whitespace are accepted only when explicitly enabled. Binary file decoding and encryption are outside this tool.

Sources

RFC 4648: Base64 and base64url

Your inputs stay on this device. Only optional, consented page visits are measured. Input values, files, filenames and processing logs are not sent to Analytics.

When switching languages, text, settings and selected files are temporarily kept on this device. Transfers are removed after restoring; interrupted transfers are cleaned up on a later visit. Inputs and files are never uploaded.