Decode a Base64 String
Decode Base64 strings
Hello, world!
What is Base64 Decoder?
Decode a Base64 string back to UTF-8 text. Accepts both standard and URL-safe alphabets, tolerates internal whitespace (so pasted multi-line output works), and re-pads strings that are missing their = padding. Throws a clear error when the input contains non-alphabet characters so you don't get mysterious mojibake.
How do I use Base64 Decoder?
- Paste the Base64 string into the input panel.
- The decoded text appears on the right; errors are flagged inline.
- Copy the result.
When should I use Base64 Decoder?
Base64 Decode is the inverse of Base64 Encode. For decoding a JWT specifically (three-segment format with header + payload + signature), use JWT Decoder for cleaner output. For a Base64 image payload, use Base64 to Image.
Frequently asked questions
Why does my decoded output look like garbage?
Because the input was binary; an image or zip, not text. The decoder outputs UTF-8 if possible; for binary data, use the "Decode as file" option to download the bytes.
My base64 says "invalid"; what gives?
Common causes: extra whitespace, wrong padding, or the input was URL-safe base64 (using -/_) while the decoder was set to standard. Toggle URL-safe mode, or strip whitespace and re-paste.
Can it handle data URIs?
Yes. Paste a full data:image/png;base64,... URI and the tool strips the prefix automatically before decoding.
Is my file uploaded anywhere?
No. Everything runs in your browser. Your files never leave your device, and there is no server component for this tool.
Tools that pair well with Base64 Decoder
- Base64 Encoder encode text to base64, free and in your browser.
- Base64 to Image Converter decode back into a file, free and in your browser.
- URL Decoder decode url encoding, free and in your browser.
- JWT Decoder inspect jwt payloads, free and in your browser.