Caesar cipher and ROT13 API: shift letters by any amount
Encode or decode text with a Caesar cipher: every letter A-Z shifted by 1-25 places (13, the default, is ROT13), case kept, digits and punctuation untouched. decode=true shifts back. Use for puzzles, spoiler hiding and teaching; it is not encryption.
When to use it
- Apply ROT13 to hide spoilers or puzzle answers
- Encode or decode a Caesar cipher with any shift from 1 to 25
- Teach the basics of substitution ciphers
Inputs
| Name | Type | Description |
|---|---|---|
text (required) | string | The text |
shift | integer | Places to shift, -25 to 25 (default 13 = ROT13) |
decode | string | true to shift back |
Request
Over HTTP, with a card key from /credits:
curl -H "Authorization: Bearer adt_…" "https://agent-data-tools.revmesh2074.workers.dev/text/caesar?text=Hello%2C%20World!"Or one of your 25 free calls, no key:
curl "https://agent-data-tools.revmesh2074.workers.dev/text/caesar?text=Hello%2C%20World!&trial=1"Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum or Solana over x402; Base or Tempo over MPP) and retries.
Example result
{
"result": "Uryyb, Jbeyq!",
"shift": 13
}From an AI agent (MCP)
Add the MCP server to Claude, Cursor or any MCP client. This tool is text_caesar, and the first 25 successful calls are free:
https://agent-data-tools.revmesh2074.workers.dev/mcpQuestions
Is this encryption?
No, it is a simple letter shift and offers no security.
What happens to digits and punctuation?
They are left unchanged; letters keep their case.
How do I pay?
Each successful call costs $0.01; failed calls are not charged. The first 25 calls are free. Then pay with card credits (from $5) or per call in USDC over x402 or MPP. No account or API key is needed.