About Base64 Decoder
Base64 is a notation for encoding arbitrary byte data using a restricted set of symbols that can be conveniently used by humans and processed by computers. This operation decodes data from an ASCII Base64 string back into its raw format. e.g. aGVsbG8= becomes hello
Input: text. Output: binary bytes.
Format reference: From Base64 background and specification
Example
Use “Try example” to load this public sample and its settings, then run it.
Input
SGVsbG8sIHdvcmxkIQ==
Result
Hello, world!
Standard Base64 or Base64url?
Standard Base64 uses + and /; Base64url uses - and _. Choose the alphabet used by your source. Padding and removal of non-alphabet characters are separate options.
Why is the result unreadable?
Base64 can represent any bytes, including images, compressed data and encrypted content. A binary result is shown as hex. Download preserves the original bytes; Base64 to hex is useful for inspecting them.
Is decoding decryption?
No. Anyone with a Base64 value can decode it. A decoded JSON document or token is not authenticated by decoding.
Parameters
| Parameter | Default value | Input and choices |
|---|---|---|
| Alphabet | "A-Za-z0-9+/=" | Escape sequences such as \n, \r and \t are supported17 Available choices
|
| Remove non-alphabet chars | true | On or off |
| Strict mode | false | On or off |
Before interpreting the result
Choose a decoder for an encoded payload, an encoder for transport, or a converter for structured data. Hex and Base64 represent bytes; converting formats does not encrypt or authenticate them.
How to use this page
- Paste your input or open a local file.
- Adjust tool options if needed, then choose Run tool.
- Copy the result or download the original output bytes.
Inputs and results are not added to the public catalogue or saved in the URL. Processing happens in your browser; HTTP Request and DNS over HTTPS send the requests you explicitly run. Files up to 128 MiB can be opened; decompression and image tools may have smaller processing limits. Large results have a shortened preview. Text and HTML downloads use UTF-8; binary downloads preserve output bytes. Pasted text follows browser newline handling; open a file when exact input bytes matter.