Base64 Encode / Decode

Base64 on the command line

echo -n 'hello' | base64          # aGVsbG8=
echo 'aGVsbG8=' | base64 -d       # hello
base64 -w0 file.bin               # no line wrapping (GNU)

Kubernetes secrets

Values in a Kubernetes Secret under data: are Base64-encoded — not encrypted. Anyone who can read the Secret can decode it. Use stringData: to write plain values, and enable encryption at rest or an external secrets manager.

kubectl get secret my-secret -o jsonpath='{.data.password}' | base64 -d

Base64 vs Base64URL

Base64URL replaces + with - and / with _ and usually drops = padding, so it is safe in URLs and filenames. JWTs use Base64URL.