Base64 Decoder Online

Decode base64 string online — paste any base64 code and read the original text instantly. Use the free Base64 Decoder Online below — enter your values and get instant results, right in your browser. Logic: base64 maps every 3 input bytes to 4 ASCII characters (A-Z, a-z, 0-9, +, /) with = padding. Decoding reverses the mapping using Unicode-safe conversion, so multi-byte characters like emoji survive the round trip.

How to use the Base64 Decoder Online

Base64 is the encoding that turns data into plain ASCII text — you meet it in email attachments, API tokens, data URLs and configuration files. When you need to see what a base64 string actually says, this tool lets you decode base64 string online in one click, with proper Unicode support so Urdu, Arabic and emoji decode correctly too. It also encodes text to base64 when you need the reverse direction.

  1. Paste the base64 string into the input area.
  2. Confirm "Base64 Decode" is selected in the Method dropdown.
  3. Click Convert to reveal the original text.
  4. If you see an error, the input is not valid base64 — check for missing characters.
  5. Click Copy to copy the decoded text, or switch to Encode mode for the reverse.

Formula

Logic: base64 maps every 3 input bytes to 4 ASCII characters (A-Z, a-z, 0-9, +, /) with = padding. Decoding reverses the mapping using Unicode-safe conversion, so multi-byte characters like emoji survive the round trip.

Worked example

Input "SGVsbG8gV29ybGQh", method Base64 Decode, click Convert. Output: "Hello World!". Encoding "Hello World!" back returns the same "SGVsbG8gV29ybGQh" string, confirming a perfect round trip. Invalid strings trigger a clear error, so check for missing characters or line breaks and try again.

Frequently asked questions

No. Base64 is just an encoding — anyone can decode it. Never use it to hide passwords or secrets.

The string may be truncated, contain spaces or line breaks, or use URL-safe variants (- and _). Clean it up and try again.

Yes. The tool uses Unicode-safe conversion, so non-English text and emoji decode correctly.

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