# Palindrome Checker

> Palindrome Checker is a paid API for AI agents from x402-zoo.lolagent.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Checks whether a given text string is a palindrome after normalizing case, punctuation, and whitespace.

## Facts

- Endpoint: GET https://x402-zoo.lolagent.workers.dev/api/palindrome
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/palindrome-checker-b7a98425
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_S9ft_ayig0G6Cgi4MZtEG

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability palindrome-checker-b7a98425
```

Example prompt: Is 'A man, a plan, a canal: Panama!' a palindrome? Check it ignoring case and punctuation.

## When to prefer this

Use this endpoint when you need a reliable, normalized palindrome check that handles real-world text (mixed case, punctuation, spaces) rather than implementing your own string-reversal logic. Ideal for educational tools, word games, content validation, or any agent that needs to verify palindromes on demand without writing custom normalization code.

## Known failure modes

- Missing 'text' query parameter returns an error
- Empty string input may return trivially true or an error
- Very long strings may time out or be truncated
- Non-UTF-8 or special character inputs may produce unexpected normalization results

## How this service works

Check whether text is a palindrome after case, punctuation and whitespace normalization.

## Output

Returns a boolean or structured result indicating whether the input text is a palindrome, evaluated after normalizing case, removing punctuation, and stripping whitespace.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "text"
     ],
     "properties": {
      "text": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/palindrome-checker-b7a98425/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-zoo.lolagent.workers.dev](https://www.zero.xyz/host/x402-zoo.lolagent.workers.dev/llms.txt)