🔄 Encoding Comparison Tool – Side-by-Side Format Analysis
When you transmit data over APIs, embed content in HTML, or store binary data as text, the encoding format you choose matters. Different encodings trade off compactness, readability, and compatibility in different ways. The Encoding Comparison Tool lets you encode any string through multiple schemes simultaneously so you can compare results, output sizes, and overhead at a glance — without switching between separate tools.
Supported Encoding Formats
The tool supports 11 widely used encoding schemes, all computed natively in the browser without sending your data anywhere:
| Encoding | Typical Use | Overhead (approx.) |
|---|---|---|
| Base64 | Email attachments (MIME), data URIs, JWT tokens | +33% |
| Base64 URL-safe | URL query parameters, OAuth tokens, filenames | +33% (no padding) |
| Hex | Cryptographic hashes, byte-level debugging, color codes | +100% |
| URL Encoding | HTTP query strings, form data, path parameters | Varies |
| HTML Entities | Safe rendering in HTML documents, escaping special chars | Varies |
| Binary | Teaching, low-level protocol analysis | +700%+ |
| Octal | Unix file permissions, legacy systems, C string literals | +200% |
| ROT13 | Simple obfuscation, spoiler text, Usenet traditions | 0% (same length) |
| Unicode Escapes | JSON strings, JavaScript source code, Python source code | Varies by script |
| ASCII Codes | Documentation, teaching decimal code points | Varies |
| UTF-8 Bytes | Protocol headers, byte-stream debugging, file specs | +200–400% for non-ASCII |
Understanding Size Overhead
Every encoding adds overhead because it must represent arbitrary bytes using a limited "safe" character set. The size overhead percentage tells you how much larger the encoded output is compared to the original input character count:
- Base64 encodes every 3 bytes as 4 characters, yielding a fixed
+33%overhead. It is the standard choice when you need compact text-safe binary transfer. - Hex represents each byte as 2 hex digits, always doubling the size (
+100%). It is human-readable and widely used for cryptographic digests. - URL encoding only encodes characters that are not URL-safe — ASCII letters, digits,
-,_,., and~pass through unchanged, while everything else becomes%XX(3 chars per byte). - Binary converts every byte to 8 characters of
0s and1s with a space separator, resulting in very large outputs — useful for learning but impractical for storage.
Auto-Detect & Decode Mode
The Decode / Detect tab accepts an unknown encoded string and uses heuristic pattern matching to identify its format:
- A string matching
/^[A-Za-z0-9+/]+=*$/with length divisible by 4 is tested as Base64. - A string containing
-or_but no+or/is tested as Base64 URL-safe. - A string containing only hex digits is tested as Hex.
- A string containing
%XXsequences is identified as URL encoding. - A string with
&...;patterns is identified as HTML entities.
A confidence indicator (High / Medium / Low) reflects how strongly the input matches the detected format. You can also force-decode using the "Decode as…" dropdown and then click Re-encode to send the decoded result back to the comparison table.
Practical Tips
- Use Base64 URL-safe for JWT payloads, OAuth state parameters, and any value embedded in a URL — the absence of
+and/eliminates URL-escaping collisions. - Use HTML Entities when inserting user-generated content into HTML to prevent XSS attacks caused by unescaped
<,>, or&. - Use Export CSV to capture a snapshot of all encoding results for documentation or audit purposes.
- Toggle off rarely-needed formats (like Binary or Octal) to keep the table focused on the encodings relevant to your task.