🔀 ROT13 Encoder/Decoder

🔧 Algorithm

📝 Input Text

📤 Output

ℹ️ Algorithm Info

Algorithm: {{ algorithm.toUpperCase() }}
Characters affected: {{ algorithm ==='rot13' ?'Letters only (A-Z, a-z)' :'All printable ASCII (33-126)' }}
Input length: {{ inputText.length }} chars
Output length: {{ outputText.length }} chars
Note: {{ algorithm.toUpperCase() }} is its own inverse - applying it twice returns original text

📚 Character Mapping Examples

A-M → N-Z:
A→N, B→O, C→P, D→Q
E→R, F→S, G→T, H→U
I→V, J→W, K→X, L→Y, M→Z
N-Z → A-M:
N→A, O→B, P→C, Q→D
R→E, S→F, T→G, U→H
V→I, W→J, X→K, Y→L, Z→M
Example mappings:
! → P," → Q, # → R
0 → _, 1 → `, 2 → a
A → p, B → q, C → r
Reverse mappings:
P → !, Q →", R → #
_ → 0, ` → 1, a → 2
p → A, q → B, r → C
⚠️ {{ error }}

ℹ️ About ROT13 Encoding

ROT13 is a fixed Caesar-style substitution cipher that rotates each English letter by 13 places: A becomes N, B becomes O, and N wraps back to A. Because the Latin alphabet has 26 letters, the same operation both encodes and decodes the text. This makes it useful for quick spoiler hiding, puzzle text, forum examples, and safe demonstrations of substitution ciphers.

ROT13 is commonly used where readers should be able to reveal text without a password. The classic netiquette guidance in RFC 1855 mentions ROT13 as a way to mark spoiler material, while the general shift-cipher idea comes from the Caesar cipher. Python also documents rot_13 as a standard text-to-text codec in its codec registry.

  • ROT13 encoder/decoder: convert plain text to ROT13 or reveal ROT13 text with the same button.
  • Spoiler text converter: hide answers, punchlines, puzzle hints, and forum spoilers without encryption.
  • ROT47 converter: rotate visible ASCII punctuation, digits, and letters for broader text obfuscation.
  • Caesar cipher teaching aid: show how modular alphabet rotation works before moving to keyed ciphers.

How the rotations work:

  • ROT13: rotates only A-Z and a-z; digits, spaces, punctuation, and Unicode characters are preserved.
  • ROT47: rotates visible printable ASCII characters from ! through ~, leaving spaces and non-ASCII text unchanged.
  • Case preservation: uppercase letters stay uppercase and lowercase letters stay lowercase.
  • Round trip: applying ROT13 twice, or ROT47 twice, returns the original text.

Examples: Hello World! becomes Uryyb Jbeyq! with ROT13, and w6==@ (@C=5P with ROT47. ROT47 works over the visible ASCII range defined by the historical RFC 20 ASCII character set.

Strength note: ROT13 and ROT47 are obfuscation, not encryption. They have no secret key, preserve obvious text patterns, and can be reversed instantly by anyone who recognizes the scheme. Use them for readability control, examples, and games, never for passwords, tokens, private messages, or confidential data.

API Usage Example:

POST /api/tools/encoding-decoding/rot13
Content-Type: application/json

{
    "text": "Hello World",
    "operation": "encode",
    "rotation": 13
}
Ready