Base64 Decode in Python — Complete Guide (b64decode, urlsafe, padding fix)

When an API returns a content field that looks like eyJob3N0IjogImRiLXByb2Qi… , or your secrets manager hands you an encoded credential, or you need to extract a JWT payload — Python base64 decode is your first stop. The built-in base64 module handles all of it, but the small details around bytes vs strings, URL-safe alphabets, and missing padding catch almost every developer at least once. This guide covers base64.b64decode() , urlsafe_b64decode() , automatic padding repair, decoding from files and HTTP responses, CLI tools, input validation, and four common mistakes with before/after fixes — all runnable Python 3.8+ examples. If you just need a quick one-off decode without writing code, ToolDeck's Base64 Decoder handles both standard and URL-safe Base64 instantly in your browser. Key takeaways: base64.b64decode(s) is built into Python stdlib — no install required; always returns bytes, not str Chain .decode("utf-8") after b64decode() to convert bytes to a Python string For URL-safe B