How to Use the Base64 Decoder
- Paste the Base64-encoded string into the input box.
- The decoded text appears instantly below.
- If the input isn't valid Base64, an error message explains why.
How Base64 decoding works
Base64 decoding reverses the encoding process, converting groups of 4 Base64 characters back into 3 original bytes. Since it is a well-defined, reversible transformation, decoding is deterministic — the same encoded input always produces the same output.
Base64 is not encryption
It bears repeating: Base64 provides no confidentiality. It is a data format transformation, not a security mechanism. Anyone — including this tool — can decode Base64 without any password, key, or special access.
Common decode errors
Decoding fails when the input contains characters outside the Base64 alphabet, has incorrect padding, or has been truncated (for example, if only part of a Base64 string was copied). Whitespace and line breaks inside the string are usually tolerated, but stray characters from a different format are not.
Example
SGVsbG8sIFdvcmxkIQ==
Hello, World!
Tips
- If decoding fails, check for missing characters or accidental line breaks pasted into the middle of the string.
- Base64 decoding never requires a password — if a tool asks for one, it is not doing standard Base64.
Frequently Asked Questions
Do I need a password to decode Base64?
No. Base64 is not encryption, so no password or key is ever required to decode it.
Why did decoding fail?
The most common cause is an incomplete or corrupted string — check that you copied the entire encoded value with no missing characters.
Is my input sent to a server?
No, decoding happens entirely client-side in your browser.