How to Decode Base64
Decoding reverses Base64 back to bytes, then to text with UTF-8. Invalid characters should fail loudly. Success does not mean the original message was secret.
Steps
- Paste the Base64. Whitespace is usually safe to ignore.
- Map the alphabet back to bytes. Reject characters outside
A–Z a–z 0–9 + / =(or the URL-safe-_variant if you are using that alphabet). - Interpret the bytes as UTF-8 if you expect text.
The MultiConvers Base64 decoder does this locally and shows an error instead of a half-decoded string.
Example
SGVsbG8= decodes to Hello. R8O2dGVib3Jn decodes to Göteborg because the encoder used UTF-8.
SGVsbG8 without padding may still decode. SGVsbG8%% should not.
This is still not encryption
If the text was only Base64, anyone can recover it. Read what Base64 is before treating a blob as hidden. To go the other way, encode Base64.
FAQ
- The decode looks like nonsense. Is that encryption?
No. You probably decoded something that was not UTF-8 text, or the string was truncated. Base64 itself is not a cipher.
- Should I ignore spaces in the input?
Yes for typical pasted payloads. Line breaks are common in PEM-style blocks. The MultiConvers tool strips whitespace before it decodes.
Related guides
What Is Base64?
Base64 is a way to write binary data using 64 ASCII characters. It is encoding, not encryption. Anyone who sees the string can decode it.
How to Encode Base64
Convert text to UTF-8 bytes, then to Base64. The result is longer ASCII, not a secret. Unicode and emoji need the UTF-8 step or they will be corrupted.
Related tools
See all guides.