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RFC 4648 Compliant Utility
Base64 Encoder & Decoder (UTF-8 & URL-Safe)
Encode plain text into binary-to-text Base64 or decode Base64 back into readable UTF-8 strings. Features live bi-directional translation, URL-safe mode, and zero network leakage.
Plain Text (UTF-8)
0 chars
Base64 Output
0 chars
How Base64 Encoding Works: Mathematics & RFC 4648
Base64 is a binary-to-text encoding scheme designed to transmit arbitrary binary data across channels and protocols (like email MIME, JSON payloads, and HTTP Authorization headers) that are historically designated for textual data.
The 6-Bit Translation Mechanism
Input: 3 Octets (3 × 8 bits = 24 bits)
Output: 4 Base64 Digits (4 × 6 bits = 24 bits)
Overhead: Base64 increases raw byte size by exactly 33.3% (≈ 4/3 ratio)
Standard vs. URL-Safe Base64
- Standard Base64: Uses characters
A-Z,a-z,0-9, plus+and/, with=for padding. - URL-Safe Base64: In HTTP query parameters and JWT tokens,
+and/have special reserved meanings. URL-safe Base64 replaces+with-(dash) and/with_(underscore), often omitting padding=.
Frequently Asked Questions
No! Base64 is strictly an encoding format, NOT encryption. It offers zero confidentiality or security, as anyone can decode it instantly. Do not use Base64 to conceal passwords or sensitive data without true cryptographic encryption (e.g. AES-GCM).
The '=' character is a padding token. Because Base64 processes data in 3-byte blocks, if your input has 1 remaining byte, it appends '=='. If it has 2 remaining bytes, it appends '='.
Privacy Commitment: Zero network transmission. 100% Client-Side browser sandboxed execution.