# GPT-5.5 Paid Chat via x402 USDC (Compact GET)

> GPT-5.5 Paid Chat via x402 USDC (Compact GET) is a paid API for AI agents from gpt55.558686.xyz, paid per call via x402, $0.110876/call, status unknown (last checked 2026-09-13).

Provides low-cost OpenAI-compatible GPT-5.5 chat completions via a GET endpoint, paid with USDC on Base via x402 protocol, supporting summarization, translation, QA, and coding help.

## Facts

- Endpoint: GET https://gpt55.558686.xyz/v1/paid/chat
- Price: $0.110876/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gpt-5-5-paid-chat-via-x402-usdc-compact-get-15ee80f4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_STSxBRCns4jDojyKV_8D-

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 gpt-5-5-paid-chat-via-x402-usdc-compact-get-15ee80f4
```

Example prompt: Summarize the following article in 3 bullet points using GPT-5.5: 'Quantum computing researchers have achieved a new milestone in error correction, reducing qubit decoherence by 40% using a novel topological approach.' Keep the response under 200 tokens.

## When to prefer this

Choose this endpoint when you need low-cost, keyless GPT-5.5 completions paid per-use via x402 USDC on Base — ideal for agents that need compact AI responses (summarization, QA, translation, coding) without OpenAI API key onboarding, and where per-call costs under $0.004 are acceptable. Prefer over OpenAI direct when avoiding key management or when integrating micropayment-native AI into autonomous agent workflows.

## Known failure modes

- Insufficient USDC payment: returns 402 Payment Required if x402 payment is missing or below minimum
- Prompt too long: returns error if input exceeds 700,000 characters
- max_tokens out of range: returns validation error if value is below 1 or above 4096
- Model unavailability: upstream GPT-5.5 outage may return 503 or timeout
- Malformed query params: missing required 'q', 'prompt', or 'message' field returns 400

## How this service works

Low-cost OpenAI-compatible GPT-5.5 paid chat over x402 Base USDC. Directory-friendly GET endpoint for compact agent responses, summarization, translation, QA, coding help, and GPT-5.5 chat completions without API-key onboarding. Market benchmark: the latest local x402.direct sample found AI-like listing prices with p25 around $0.01 and median around $0.03 per call, while this gateway advertises a $0.110876 compact GPT-5.5 entry request, $0.110876 long-output GPT-5.5 requests, and $0.523889 true max-output GPT-5.5 requests. Pay up to $0.110876 per request with x402 USDC on Base. Exact fixed-price payment and upto token-metered payment are both accepted when clients support them; upto settlements use actual response usage, a 0.0001 minimum, and the selected tier price as the cap. Public paid calls are limited to 700000 input characters and 4096 output tokens.

## Output

Returns an OpenAI-compatible JSON response with an id, model name, choices array containing the generated text, and a usage object showing token counts. The response reflects actual GPT-5.5 output for the given prompt, with billing settled via x402 USDC on Base based on actual usage up to the $0.004 cap.

## 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",
     "properties": {
      "q": {
       "type": "string"
      },
      "prompt": {
       "type": "string"
      },
      "system": {
       "type": "string"
      },
      "message": {
       "type": "string"
      },
      "max_tokens": {
       "type": "integer",
       "maximum": 4096,
       "minimum": 1
      }
     },
     "additionalProperties": true
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "id",
      "object",
      "model",
      "choices"
     ],
     "properties": {
      "id": {
       "type": "string"
      },
      "model": {
       "type": "string"
      },
      "usage": {
       "type": "object"
      },
      "object": {
       "type": "string"
      },
      "choices": {
       "type": "array"
      }
     },
     "additionalProperties": true
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gpt-5-5-paid-chat-via-x402-usdc-compact-get-15ee80f4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from gpt55.558686.xyz](https://www.zero.xyz/host/gpt55.558686.xyz/llms.txt)