Base64 Converter

Base64 requires string length to be a multiple of 4. When the original data length isn't divisible by 3, padding with "=" characters is needed. Missing or incorrect padding causes decode errors.

• Add padding: string += "=" * ((4 - len % 4) % 4)
• Valid endings: no padding, =, or ==
• Never use === (triple equals)
• Some decoders auto-fix padding issues

Valid Base64 uses only A-Z, a-z, 0-9, +, /, and = for padding. Characters like %, space, or line breaks cause decoding failures. URL encoding can corrupt Base64 strings.

• Valid chars: A-Z, a-z, 0-9, +, /, =
• Remove whitespace and line breaks
• Check for URL encoding corruption
• Use regex to filter invalid characters

Standard Base64 uses + and / which are problematic in URLs. URL-safe Base64 replaces them with - and _ respectively. Some implementations also handle padding differently.

• Standard: uses + and / characters
• URL-safe: uses - and _ instead
• Padding may use _ instead of =
• Use appropriate decoder for each variant

Data URIs include prefixes like "data:image/png;base64," which must be removed before decoding. File uploads and embedded content often include this metadata.

• Remove "data:*;base64," prefixes
• Check for MIME type information
• Handle both with and without prefixes
• Validate actual Base64 content separately

Different platforms handle Base64 padding differently. GNU's base64 traditionally required proper padding, while Mac/BSD were more lenient. Recent updates (2024) made GNU more flexible.

• GNU coreutils 9.5+: padding optional
• Older GNU: strict padding required
• Mac/BSD: generally lenient
• Test across target platforms

Binary data contains bytes that aren't valid text characters. Storing binary directly in text systems corrupts the data. Base64 ensures safe transport through text-only channels.

• Text systems can't store arbitrary bytes
• Base64 creates text-safe representation
• Essential for JSON, XML, email attachments
• Always encode binary before text storage

Base64 encoding increases data size by ~33% (4 characters for every 3 bytes). For large files or frequent operations, this overhead impacts performance and storage requirements.

• Size increase: approximately 133% of original
• Consider compression before encoding
• Use streaming for large files
• Cache encoded results when possible

Reliable Base64 handling requires validation, proper error handling, and awareness of platform differences. Use appropriate libraries and validate both input and output data.

• Validate input before encoding/decoding
• Handle both standard and URL-safe variants
• Implement proper error handling
• Test with edge cases and large data