ROT13 Encoder Decoder

WHAT IT DOES

ROT13 Encoder Decoder applies the ROT13 Caesar cipher to text, shifting each letter by 13 positions in the alphabet. The tool works both ways—encoding and decoding are the same operation. You can customize the rotation value from 1 to 25, not just 13. The tool displays the original, encoded, and decoded versions side by side, with a character map showing each letter's transformation. Copy any version with one click, or use the swap function to quickly exchange input with output. The auto-encode feature updates results as you type.

WHERE IT RUNS

The extension runs entirely within your browser's local environment using the BotGentz framework. All text encoding, decoding, and character mapping occur on your machine without any network requests. No text data, transformation history, or user activity is ever transmitted, uploaded, or stored externally. The tool works on any website and respects the browser's security boundaries, operating within the isolated extension sandbox. ROT13 encoding uses pure JavaScript string manipulation.

HOW TO USE

Click the extension toolbar icon to open the ROT13 Encoder Decoder panel. Enter text in the input area—the results update automatically if auto-encode is enabled. The output shows the original, encoded, and decoded versions. Click "Copy" next to any version to copy just that version. Click "Copy" at the bottom to copy based on your selected format (Encoded, Decoded, Original, or All). Click "Swap Input/Output" to replace the input with the encoded output. Adjust the "Rotation" value (1-25) to use a custom Caesar cipher shift. Toggle "Auto encode on input" to enable or disable automatic updates. Toggle "Show character map" to display a grid showing each letter and its transformed counterpart. Toggle "Preserve case" to control whether uppercase and lowercase are maintained. Choose the "Copy Format" to control what is copied when using the main copy button.

THE ROT13 ENGINE — WHY IT WORKS

Most ROT13 tools implement the cipher with a fixed rotation of 13, limiting their utility. This tool uses a configurable rotation engine that supports any shift from 1 to 25. The algorithm checks each character's Unicode code point: for uppercase letters (65-90) and lowercase letters (97-122), it calculates the rotated position using modular arithmetic. The formula (code - base + rotation) % 26 shifts the letter within its alphabet range, with the modulo operation handling wrap-around. The character map is generated by iterating through the input text, tracking unique letters, and displaying each with its transformed counterpart. The three-view output (original, encoded, decoded) demonstrates that ROT13 is its own inverse—encoding twice returns the original text. This approach provides both educational value and practical utility for text manipulation.

THE PANEL

The ROT13 Encoder Decoder panel is fully draggable by its title bar and remembers its position on screen per website. It snaps to the edges of your browser window for clean alignment. Collapse the panel to a compact icon strip using the minimize button, restoring it with a single click. Resize the panel by dragging any edge or corner; the input area, output sections, and character map adjust proportionally. Press the Escape key to close the panel instantly. The panel maintains independent state for each browser tab, allowing you to encode text in multiple tabs simultaneously.

PLEASE NOTE

This extension requires the free BotGentz extension framework to be installed and enabled. ROT13 is a simple substitution cipher and is not cryptographically secure—it provides no real encryption. The tool is intended for obfuscation, puzzle-solving, and educational purposes. Custom rotation values (1-25) work with any number; rotation by 13 is the classic ROT13. The character map shows unique letters only; repeated letters appear once. All text data is processed locally and is never transmitted, logged, or shared. The extension requests no network permissions and functions entirely offline. The source code is fully auditable and available for review.