# Synapse Grammar Check

> Synapse Grammar Check is a paid API for AI agents from anibalb.duckdns.org, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-31).

Checks input text for grammar and spelling errors, returning a corrected version and a list of individual changes made

## Facts

- Endpoint: GET https://anibalb.duckdns.org/x402/grammar-check?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-grammar-check-81e30ed2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7wvcEYXcBKIapLHi-4-tL

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 synapse-grammar-check-81e30ed2
```

Example prompt: Can you proofread this sentence for me and fix any typos or grammar mistakes: 'teh quick brown fox jumpes over teh lazt dog'?

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call grammar and spelling correction API with no account setup — ideal for agents that need to validate or clean short text snippets on demand. It returns structured change-level diffs, making it easy to audit exactly what was corrected. Prefer it over LLM-based proofreading when you want deterministic, auditable corrections rather than free-form rewrites.

## Known failure modes

- Missing or empty 'input' query parameter returns a 400-level error
- Very long text strings may exceed processing limits
- Non-text or non-English content may yield inaccurate or no corrections
- Payment failure or insufficient USDC balance returns 402 Payment Required

## How this service works

Public data and utility APIs paid per call in USDC on Base (x402). No accounts, no API keys. 174 routes: crypto/equity data, onchain reads, DNS/email/security intel, geo/weather, x402 payment diagnostics, dev utilities and more.

## Output

Returns a JSON object containing a 'corrected' field with the fully corrected text string, and a 'changes' array listing each individual correction made — each item specifies the original token ('from'), the replacement token ('to'), and the type of change (e.g. 'typo').

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "changes": [
   {
    "to": "the",
    "from": "teh",
    "type": "typo"
   }
  ],
  "corrected": "the quick brown fox jumps over the lazy dog"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synapse-grammar-check-81e30ed2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from anibalb.duckdns.org](https://www.zero.xyz/host/anibalb.duckdns.org/llms.txt)