Base64 converts binary data (like images or files) into ASCII text for safe storage or transmission. In Python, decoding it is simple using the built-in base64 module, no extra installation required.
Methods for Decoding Base64 Data in Python
Here are a few simple and effective ways to decode Base64-encoded strings in Python using built-in modules
1. Basic Base64 String Decoding
Use base64.b64decode() to decode a Base64-encoded string into bytes, and then convert to a readable format.
import base64
# Base64 encoded string (e.g., from an API or file)
encoded_data = "SGVsbG8gd29ybGQh"
# Decode to bytes
decoded_bytes = base64.b64decode(encoded_data)
# Convert bytes to string
decoded_str = decoded_bytes.decode('utf-8')
print(decoded_str) # Output: Hello world!
Note: Always decode bytes to utf-8 (or your desired encoding) if you want human-readable text.
2. Decoding Base64 from a File
If your Base64 data is saved in a file, you can read and decode it easily:
import base64
# Read Base64 string from a file
with open("data.txt", "r") as file:
base64_data = file.read()
# Decode
decoded = base64.b64decode(base64_data)
# Optionally write decoded binary to another file
with open("output.bin", "wb") as output_file:
output_file.write(decoded)
This is useful when working with encoded images, PDFs, or binary files.
Also Read: How Much Does It Cost To Build A Web App With Python in 2025?
3. Decode and Handle Invalid Input (Safely)
To avoid crashing on invalid Base64 data, use try-except:
import base64
invalid_data = "NotValidBase64==="
try:
result = base64.b64decode(invalid_data)
print(result)
except Exception as e:
print("Decoding failed:", e)
Tip
When decoding user input or API data, always validate or sanitize it first. Malformed Base64 strings can raise exceptions or security issues if not handled correctly.
