Python base64 Module: Encoding Binary Data

import base64
 
# Encode bytes to base64
data = b"Hello, World!"
encoded = base64.b64encode(data)
print(encoded)  # b'SGVsbG8sIFdvcmxkIQ=='
 
# Decode back to bytes
decoded = base64.b64decode(encoded)
print(decoded)  # b'Hello, World!'

import base64
 
# String → base64 string
text = "Hello, World!"
encoded = base64.b64encode(text.encode()).decode()
print(encoded)  # 'SGVsbG8sIFdvcmxkIQ=='
 
# Base64 string → string
decoded = base64.b64decode(encoded).decode()
print(decoded)  # 'Hello, World!'

import base64
 
data = b'\xfb\xff\xfe'  # Contains bytes that produce + and /
 
# Standard (not URL-safe)
standard = base64.b64encode(data)
print(standard)  # b'++/+'
 
# URL-safe (- instead of +, _ instead of /)
urlsafe = base64.urlsafe_b64encode(data)
print(urlsafe)  # b'--_-'
 
# Decode URL-safe
decoded = base64.urlsafe_b64decode(urlsafe)

import base64
 
# Encode file to base64
with open('image.png', 'rb') as f:
    encoded = base64.b64encode(f.read())
 
# Decode base64 to file
with open('output.png', 'wb') as f:
    f.write(base64.b64decode(encoded))

import base64
import mimetypes
 
def to_data_url(filepath):
    """Convert file to data URL."""
    mime_type, _ = mimetypes.guess_type(filepath)
    with open(filepath, 'rb') as f:
        encoded = base64.b64encode(f.read()).decode()
    return f"data:{mime_type};base64,{encoded}"
 
# Usage
data_url = to_data_url('image.png')
# data:image/png;base64,iVBORw0KGgo...

import base64
 
data = b"Hello"
 
# Base32 (A-Z, 2-7)
b32 = base64.b32encode(data)
print(b32)  # b'JBSWY3DP'
 
# Base16 (hex)
b16 = base64.b16encode(data)
print(b16)  # b'48656C6C6F'
 
# Decode
base64.b32decode(b32)
base64.b16decode(b16)

import base64
 
data = b"Hello, World!"
 
# ASCII85 encoding
a85 = base64.a85encode(data)
print(a85)  # b'87cURD]j7BEbo80'
 
# Base85 (Git/Mercurial style)
b85 = base64.b85encode(data)
print(b85)  # b'NM&qnZy;B1a%^M'

import base64
import json
 
def encode_payload(payload: dict) -> str:
    """Encode dict as URL-safe base64."""
    json_bytes = json.dumps(payload).encode()
    return base64.urlsafe_b64encode(json_bytes).decode().rstrip('=')
 
def decode_payload(encoded: str) -> dict:
    """Decode URL-safe base64 to dict."""
    # Add padding back
    padding = 4 - len(encoded) % 4
    if padding != 4:
        encoded += '=' * padding
    json_bytes = base64.urlsafe_b64decode(encoded)
    return json.loads(json_bytes)
 
payload = {'user': 'alice', 'exp': 1234567890}
token = encode_payload(payload)
print(token)  # 'eyJ1c2VyIjoiYWxpY2UiLCJleHAiOjEyMzQ1Njc4OTB9'

import base64
from email.mime.base import MIMEBase
from email import encoders
 
def create_attachment(filepath):
    """Create base64-encoded email attachment."""
    with open(filepath, 'rb') as f:
        data = f.read()
    
    part = MIMEBase('application', 'octet-stream')
    part.set_payload(data)
    encoders.encode_base64(part)
    
    return part

import base64
import requests
 
def upload_image(filepath, api_url):
    """Upload image as base64 to API."""
    with open(filepath, 'rb') as f:
        image_data = base64.b64encode(f.read()).decode()
    
    response = requests.post(api_url, json={
        'image': image_data,
        'filename': filepath
    })
    return response.json()

import base64
 
def img_to_html(filepath):
    """Convert image to inline HTML img tag."""
    with open(filepath, 'rb') as f:
        encoded = base64.b64encode(f.read()).decode()
    
    ext = filepath.split('.')[-1]
    mime = {'png': 'image/png', 'jpg': 'image/jpeg', 'gif': 'image/gif'}
    
    return f'<img src="data:{mime.get(ext, "image/png")};base64,{encoded}" />'

import base64
 
def basic_auth_header(username: str, password: str) -> str:
    """Create HTTP Basic Auth header."""
    credentials = f"{username}:{password}"
    encoded = base64.b64encode(credentials.encode()).decode()
    return f"Basic {encoded}"
 
header = basic_auth_header("user", "pass")
# 'Basic dXNlcjpwYXNz'

import base64
 
# Different input lengths
base64.b64encode(b'a')    # b'YQ=='    (2 padding)
base64.b64encode(b'ab')   # b'YWI='    (1 padding)
base64.b64encode(b'abc')  # b'YWJj'    (no padding)
base64.b64encode(b'abcd') # b'YWJjZA==' (2 padding)

import base64
 
# Standard Base64
base64.b64encode(bytes)    # bytes → base64 bytes
base64.b64decode(bytes)    # base64 bytes → bytes
 
# URL-safe Base64
base64.urlsafe_b64encode(bytes)
base64.urlsafe_b64decode(bytes)
 
# Other encodings
base64.b32encode(bytes)    # Base32
base64.b32decode(bytes)
base64.b16encode(bytes)    # Base16 (hex)
base64.b16decode(bytes)
base64.a85encode(bytes)    # ASCII85
base64.a85decode(bytes)
base64.b85encode(bytes)    # Base85
base64.b85decode(bytes)