Base64 Encode & Decode in Bash

Encode or decode below — it runs locally in your browser — then grab the canonical Bash code. The base64 command ships on almost every Unix-like system, but watch the echo trap: by default echo appends a trailing newline that changes the encoded output.

Encode and decode a string

Pipe text into the base64 command to encode, and add -d to decode:

$ echo -n "Hello, world!" | base64
SGVsbG8sIHdvcmxkIQ==

$ echo "SGVsbG8sIHdvcmxkIQ==" | base64 -d
Hello, world!

Avoid line wrapping

GNU base64 wraps output at 76 characters by default. For a single line — needed for env vars and tokens — disable wrapping:

# GNU / Linux: single-line output, no wrapping
$ echo -n "Hello, world!" | base64 -w 0

# BSD / macOS: no -w flag, so strip newlines portably
$ echo -n "Hello, world!" | base64 | tr -d '\n'

Encode a file / env vars

Pass a filename straight to base64 (no echo, so no newline trap), then store it in a variable:

# encode a file to a single line
$ base64 -w 0 key.pem > key.b64

# store it in an env var, then decode at the point of use
$ export KEY_B64=$(base64 -w 0 key.pem)
$ printf "%s" "$KEY_B64" | base64 -d > key.pem

Frequently asked questions

How do I Base64 encode a string in Bash?

Pipe it into the base64 command with echo -n: echo -n "Hello, world!" | base64 returns SGVsbG8sIHdvcmxkIQ==.

How do I Base64 decode in Bash?

Add the decode flag: echo "SGVsbG8sIHdvcmxkIQ==" | base64 -d (-D on macOS) returns the original text.

How do I avoid line wrapping in Base64 output?

On Linux use base64 -w 0; on BSD/macOS there is no -w, so pipe through tr -d '\n' to get a single line.

Why does my Base64 have an extra character / wrong output?

Because echo without -n appends a trailing newline, so you encode your text plus a \n byte. Always use echo -n or printf "%s".