all Python 3base64function

base64.urlsafe_b64decode()

Base64

Decodes Base64 in the URL-safe alphabet ('-' and '_'). The counterpart of urlsafe_b64encode.

Syntax

base64.urlsafe_b64decode(s)

Up to Python 3.14 inclusive, a string without '=' padding (as in a JWT) raises binascii.Error; in 3.15 the padded parameter defaults to False and such a string passes. The portable way is to add the '=' yourself: s + '=' * (-len(s) % 4). In 3.15, accepting '+' and '/' here is deprecated and emits FutureWarning.

Examples

import base64
s = 'aGk'
print(base64.urlsafe_b64decode(s + '=' * (-len(s) % 4)))  # → b'hi'
print(base64.urlsafe_b64decode(b'-_8='))  # → b'\xfb\xff'

See also

Common errors

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