Base64 Decode

How to decode Base64

Paste a Base64 string into the box above and the decoded result appears instantly. Line breaks and spaces are ignored, and both standard and URL-safe Base64 are detected automatically. If the data is an image or a PDF you will see a preview and can download the file. Decoding happens entirely in your browser, so it is safe to use with tokens, keys and private data.

Example

SGVsbG8sIFdvcmxkIQ== decodes to Hello, World!. Each group of 4 Base64 characters encodes 3 bytes; the two = signs show that the last group carries only one byte.

Base64 vs. Base64URL

Standard Base64 (RFC 4648) uses A–Z, a–z, 0–9, + and/, with = as padding. Base64URL replaces + with - and/ with _ so the result is safe in URLs and file names, and it usually drops the padding. JWTs use Base64URL. This decoder accepts both.

Why your Base64 won't decode

• It contains characters outside the Base64 alphabet (often a stray quote, % encoding or a copied ellipsis).
• The length is wrong: valid Base64 is a multiple of 4 characters once padding is added. A length that leaves a remainder of 1 is always invalid.
• It is not Base64 at all: hex strings and encrypted data can look similar.
• It decoded, but the output is binary: choose a different charset or download it as a file.

Decode Base64 from the command line

# Linux
echo 'SGVsbG8sIFdvcmxkIQ==' | base64 -d
# macOS
echo 'SGVsbG8sIFdvcmxkIQ==' | base64 -D
# PowerShell
[Text.Encoding]::UTF8.GetString([Convert]::FromBase64String('SGVsbG8sIFdvcmxkIQ=='))
# JavaScript (browser)
new TextDecoder().decode(Uint8Array.from(atob('SGVsbG8sIFdvcmxkIQ=='), c => c.charCodeAt(0)))
# Python
import base64; base64.b64decode('SGVsbG8sIFdvcmxkIQ==').decode()