# imgnAI Katana GPT-5.5 Chat API

> imgnAI Katana GPT-5.5 Chat API is a paid API for AI agents from kat.imgnai.com, paid per call via x402, $0.052/call, status unknown (last checked 2026-10-19).

Pay-per-call chat completion endpoint powered by GPT-5.5 via the imgnAI Katana AI gateway

## Facts

- Endpoint: POST https://kat.imgnai.com/v1/text/chat-gpt-55?utm_source=zero.xyz
- Price: $0.052/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Success rate: 0% of calls made through Zero
- Rating: 1.3 / 5 from 1 review
- Activations on Zero: 1
- Tags: x402
- Canonical page: https://www.zero.xyz/c/imgnai-katana-gpt-5-5-chat-api-abc1c502
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Iuh9E8n3cvAtaKZniirsm

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 imgnai-katana-gpt-5-5-chat-api-abc1c502 -d '<json body>'
```

Example prompt: Using the Katana gateway's GPT-5.5 endpoint, send this conversation — system: 'You are a helpful assistant', user: 'Explain the difference between supervised and unsupervised learning in 3 sentences' — with a max of 300 tokens and temperature 0.7.

## When to prefer this

Choose this endpoint when you need GPT-5.5 quality responses on a pay-per-call basis without an OpenAI subscription, especially in agentic workflows using USDC micropayments via the x402 protocol. It is ideal for cost-controlled, sporadic LLM calls where you only pay per invocation at $0.05425 USDC.

## Known failure modes

- Insufficient USDC balance or failed x402 payment results in 402 Payment Required
- Invalid or missing messages array returns 400 Bad Request
- Model overload or upstream GPT-5.5 unavailability returns 503 Service Unavailable
- Malformed temperature or max_tokens values return validation errors
- Streaming connection drops mid-response if network is unstable

## How this service works

Pay-per-call AI gateway: Frontier/SOTA LLM, Image, and Video models - and proprietary low-cost imgnAI models. Includes GPT 5.5, Opus 4.8, GPT Image 2, Nano Banana 2, Seedance 2.0, Happy Horse, and Google Omni. Fully compatible with OpenAPI, HermesOS, and OpenClaw.

## Output

Returns an OpenAI-compatible chat completion object containing an array of choices (each with a message and finish reason) and a usage object detailing prompt tokens, completion tokens, and total tokens consumed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "messages"
 ],
 "properties": {
  "messages": {
   "type": "array"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/imgnai-katana-gpt-5-5-chat-api-abc1c502/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from kat.imgnai.com](https://www.zero.xyz/host/kat.imgnai.com/llms.txt)