base64

TLDR

Encode to base64

$ base64 [file]

Decode base64

$ base64 -d [file.b64]

Encode string

$ echo [text] | base64

Decode string

$ echo [ENCODED] | base64 -d

No wrapping

$ base64 -w 0 [file]

base64 encodes and decodes data using base64 encoding. Base64 represents binary data using 64 printable ASCII characters, making it suitable for transmitting binary data over text-only channels like email or JSON.
The tool is part of GNU coreutils and widely used for encoding credentials, certificates, and binary data in configuration files.

PARAMETERS

-d, --decode

Decode base64 data

-i, --ignore-garbage

Ignore non-alphabet characters when decoding

-w, --wrap=cols

Wrap lines at specified width (default: 76, 0 = no wrap)

FEATURES

- Standard RFC 4648 encoding
- 33% size increase from binary
- URL and filename safe variant
- Padding with = characters

WORKFLOW

$ # Encode file
base64 file.bin > file.b64

# Decode file
base64 -d file.b64 > file.bin

# Encode for use in JSON (no wrapping)
cat image.png | base64 -w 0

# Decode string
echo "SGVsbG8gV29ybGQ=" | base64 -d

COMMON USES

- HTTP Basic Auth - `Authorization: Basic <base64-encoded-credentials>`
- Data URLs - `data:image/png;base64,iVBORw0KG...`
- Kubernetes secrets - Encoded in YAML manifests
- JWT tokens - Header and payload sections

CAVEATS

Not encryption (easily reversible). Increases size by ~33%. Line wrapping can cause issues in some contexts. URL-safe variant needs different characters.

HISTORY

base64 has been part of GNU coreutils since version 6.0 (2006), implementing the base64 encoding standardized in RFC 4648 (2006).