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Base64 Converter

Encode text to Base64 and decode it back.

Plain Text

Base64 Encoded

About, how to use & limitations

About Base64 Converter

Base64 Converter lets you encode text to Base64 and decode Base64 back to plain text online, right in your browser. Type in either box and the other updates instantly, so it works as a Base64 encoder and a Base64 decoder at the same time. Text is handled as UTF-8, so accents, Korean, Japanese and emoji survive the round trip. Developers use it to inspect API payloads, data URIs, basic auth headers and config values. Invalid Base64 input shows an error instead of garbage, and each side has a copy button. Nothing is sent to a server.

How to use

  1. Type or paste text into the Plain Text box to see its Base64 encoding appear instantly in the Base64 Encoded box.
  2. To decode, paste a Base64 string into the Base64 Encoded box and the decoded text fills the Plain Text box.
  3. If the Base64 input is malformed, an Invalid Base64 string message appears under the box.
  4. Click Copy above either box to copy its contents to your clipboard, or CLEAR to empty both boxes and start over.

Limitations & notes

  • Each box accepts up to 100,000 characters.
  • Only standard Base64 with + and / is decoded; URL-safe strings using - and _ show an error until those characters are swapped.
  • Decoded bytes are always read as UTF-8 text, so Base64 of images or other binary files shows replacement characters instead of usable data.

FAQ

What is Base64 encoding?
Base64 represents binary data using 64 printable ASCII characters (A-Z, a-z, 0-9, + and /), with = used as padding. It lets you carry bytes through systems that only accept text, such as JSON, email or URLs in data URIs.
Is Base64 a form of encryption?
No. Base64 is an encoding, not encryption, and anyone can decode it without a key. Never use it to hide passwords or secrets.
Why is the Base64 output longer than my text?
Base64 turns every 3 bytes into 4 characters, so the encoded result is about 33% larger than the original data.
Does it work with emoji and non-English text?
Yes. Text is converted to UTF-8 bytes before encoding and decoded back as UTF-8, so any Unicode text round-trips correctly.
Why do I get "Invalid Base64 string"?
The input contains characters outside the standard Base64 alphabet or has broken padding. URL-safe Base64 that uses - and _ instead of + and / is not accepted as-is; replace those characters first.