Base64 Decoder Online
Decode Base64-encoded strings back to readable text instantly. Paste any Base64 string and get the decoded output. All processing happens locally in your browser.
How Base64 decoding works
Base64 decoding reverses the encoding process: each group of 4 Base64 characters is converted back to 3 bytes of original data. Padding characters (=) at the end indicate the number of missing bytes. The decoded output is the exact original binary data.
Troubleshooting Base64 decode errors
Common decode errors: the input contains characters outside the Base64 alphabet, incorrect padding, or the string was URL-safe Base64 (using - and _ instead of + and /). This tool handles standard Base64 and will flag invalid input with clear error messages.
Frequently Asked Questions
Why is my Base64 string not decoding correctly?
Check for URL-safe Base64 (- and _ instead of + and /), missing padding (= characters), extra whitespace, or non-Base64 characters in the input.
Can Base64 decode binary files?
Yes. Base64 can encode any binary data. This text tool decodes to text (UTF-8). For binary files like images, use a specialized Base64-to-file converter.