Base64 Encoding: Everything Developers Need to Know

Base64 encoding is everywhere - data URLs, email attachments, JWT tokens, API payloads. Here's what every developer should know. What is Base64? Base64 converts binary data into ASCII text using 64 characters (A-Z, a-z, 0-9, +, /). It increases size by ~33% but ensures safe transmission through text-only channels. Common Use Cases Use Case Example Data URLs data:image/png;base64,iVBOR... Email (MIME) Attachments encoded in Base64 JWT tokens Header.Payload.Signature API auth Authorization: Basic base64(user:pass) Embedding images <img src="data:image/png;base64,..."> JavaScript // Encode btoa ( ' Hello World ' ) // 'SGVsbG8gV29ybGQ=' // Decode atob ( ' SGVsbG8gV29ybGQ= ' ) // 'Hello World' // For Unicode (UTF-8) const encode = ( str ) => btoa ( unescape ( encodeURIComponent ( str ))); const decode = ( str ) => decodeURIComponent ( escape ( atob ( str ))); Python import base64 # Encode base64 . b64encode ( b ' Hello World ' ). decode () # 'SGVsbG8gV29ybGQ=' # Decode base64 . b64decode (