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Base64 & URL Encoder / Decoder

Free online Base64 and URL encoding/decoding tool. Safely convert text, binary data, and URI query strings with instant UTF-8 conversion in your browser.

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What is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format by translating it into a radix-64 representation. The Base64 index table consists of 64 printable characters:

  • Uppercase letters A-Z (indices 0–25)
  • Lowercase letters a-z (indices 26–51)
  • Digits 0-9 (indices 52–61)
  • Special characters + and / (indices 62–63)
  • The padding character = used to pad output blocks when the input byte count is not divisible by 3.

Base64 is commonly used when binary assets (such as images, digital certificates, cryptographic keys, or email attachments) need to be stored or transferred over media designed exclusively to handle textual data, such as MIME emails or JSON payloads.

How to Use This Encoder & Decoder

  1. Select Operation Mode: Choose Base64 Encode, Base64 Decode, URL Encode, or URL Decode using the top action buttons.
  2. Input Text: Paste or type your payload into the left input container.
  3. Live Conversion: The output panel renders the converted result automatically with zero keystroke delay.
  4. Copy or Swap: Click COPY OUTPUT to copy the string to your clipboard, or Swap Output to Input to test reciprocal decoding operations.

Understanding URL Percent-Encoding

Uniform Resource Identifiers (URIs) only permit a restricted subset of US-ASCII characters. Any character outside the unreserved character set (A-Z, a-z, 0-9, -, _, ., ~) must be percent-encoded:

  • A percent-encoded character consists of a % symbol followed by two hexadecimal digits representing the byte value.
  • For example, a whitespace character ( ) becomes %20 or +.
  • Reserved characters such as &, ?, =, and / have specific syntactic meaning in URL queries and routing paths; encoding them ensures parameters are not misinterpreted by web servers.

Base64 vs. Encryption: An Important Distinction

Crucial Security Note:
Base64 is NOT encryption. It does not protect data from unauthorized access or eavesdropping. Any person or computer program can reverse a Base64 string in microseconds without a password or key.
Base64 is solely an encoding mechanism designed for safe data transport across text-only protocols. Never use Base64 alone to store passwords, API secrets, or personal identifiable information (PII).

Frequently Asked Questions (FAQ)

Does Base64 increase file size?

Yes. Every 3 bytes of raw binary data (24 bits) are divided into four 6-bit groups, resulting in 4 Base64 characters. This causes an approximate 33% increase in data size compared to raw binary representation.

How does this tool handle international UTF-8 characters?

Standard legacy JavaScript functions like btoa() fail when encountering characters outside the Latin1 range (such as emojis or non-Latin alphabets). This utility uses the modern Web Standards TextEncoder and TextDecoder APIs to ensure 100% compliant UTF-8 byte stream processing without data corruption.