Base64 Encoder / Decoder

How to use Base64 Encoder / Decoder

1. Choose Encode for ordinary text, or Decode for a Base64 string.
2. Paste the text or encoded string into the Text field. For decoding, use the Base64 payload rather than a complete data URL.
3. Convert the text and inspect the result. If decoding fails, check the alphabet, padding, and whether the decoded bytes represent UTF-8 text.
4. Copy the output or download the text file. Use Reset to start again.

Worked example

An exact round trip using the text FyrePress.

Mode: Encode
Text: FyrePress

RnlyZVByZXNz

Switch to Decode and enter RnlyZVByZXNz to recover FyrePress. Anyone can reverse this encoding without a key.

How the conversion works

Encoding converts text into UTF-8 bytes and represents those bytes using the standard Base64 alphabet. This preserves non-ASCII text when it is decoded with the same UTF-8 convention.

Decoding uses the browser Base64 decoder and a strict UTF-8 text decoder. Invalid Base64 or bytes that are not valid UTF-8 produce an error instead of a usable text result.

Supported input and output

This tool handles text rather than arbitrary binary files. Standard Base64 commonly uses letters, digits, +, /, and optional trailing = padding. URL-safe Base64 that uses - and _ is not automatically normalized here.

Paste only the encoded payload. A data URL prefix, quoted JSON value, or surrounding markup must be removed first. Binary image or PDF bytes may be valid Base64 but cannot necessarily be decoded into UTF-8 text.

Common mistakes and limitations

Base64 is not encryption or password hashing. Encoding a password does not make it safe to share, and decoding a string does not prove it came from a trusted sender.

Large inputs use browser memory and can slow down the page. The downloaded file contains the visible text result; it is not a reconstruction of an arbitrary binary file.

Frequently asked questions