# x402engine KAT-Coder-Pro v2.5 LLM

> x402engine KAT-Coder-Pro v2.5 LLM is a paid API for AI agents from x402engine.app, paid per call via x402, $0.006508/call, status unknown (last checked 2026-10-12).

Runs the KAT-Coder-Pro v2.5 coding-specialized language model via pay-per-call HTTP 402 micropayment, returning OpenAI-compatible chat completions

## Facts

- Endpoint: POST https://x402engine.app/api/llm/kat-coder-pro-v2.5?utm_source=zero.xyz
- Price: $0.006508/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402engine-kat-coder-pro-v2-5-llm-62d82e36
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_UJbz3pJAf3wVRUwTAMAb1

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 x402engine-kat-coder-pro-v2-5-llm-62d82e36 -d '<json body>'
```

Example prompt: Use KAT-Coder-Pro v2.5 to write me a Python function that parses a JSON log file and extracts all ERROR-level entries with their timestamps — stream the response as it comes in.

## When to prefer this

Choose this endpoint when you need a coding-specialized LLM (KAT-Coder-Pro v2.5) without a subscription, paying only $0.006508 USDC per call via HTTP 402. It is ideal for agents that need OpenAI-compatible chat completions, tool/function calling, and optional streaming, especially for code generation, review, or debugging tasks where a purpose-built coding model outperforms general LLMs.

## Known failure modes

- Payment not settled via HTTP 402 — request rejected before reaching the model
- Messages array missing or malformed — 422 validation error
- Model context length exceeded — finish_reason set to 'length'
- Tool schema invalid — function definitions not accepted
- Streaming connection dropped mid-response — partial SSE received
- Unsupported sampling parameters for this model variant — silently ignored or errored per /docs/llm-capabilities.md

## How this service works

125 production APIs behind HTTP 402 micropayments. 87 LLMs, Kling V3 and Hailuo video generation, image generation, code execution, travel search, web scraping, TTS, and transaction simulation. Pay with USDC on Base, USDm on MegaETH, or USDC on Solana.

## Output

Returns an OpenAI-compatible JSON response with the model name ('kwaipilot/kat-coder-pro-v2.5'), an array of choices each containing an assistant message with role and content, a finish_reason ('stop', 'tool_calls', etc.), and optionally tool_calls. When stream=true, returns live Server-Sent Events (SSE) in OpenAI format. The top-level 'content' field is also echoed for convenience.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "bodyType",
    "body",
    "method"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "messages"
     ],
     "properties": {
      "seed": {
       "type": "integer",
       "description": "Model-supported seed; see /docs/llm-capabilities.md."
      },
      "stop": {
       "oneOf": [
        {
         "type": "string"
        },
        {
         "type": "array",
         "items": {
          "type": "string"
         },
         "maxItems": 4
        }
       ],
       "description": "Model-supported stop; see /docs/llm-capabilities.md."
      },
      "min_p": {
       "type": "number",
       "description": "Model-supported min_p; see /docs/llm-capabilities.md."
      },
      "tools": {
       "type": "array",
       "items": {
        "type": "object",
        "required": [
         "function"
        ],
        "properties": {
         "type": {
          "enum": [
           "function"
          ],
          "type": "string"
         },
         "function": {
          "type": "object",
          "properties": {
           "name": {
            "type": "string"
           },
           "strict": {
            "type": "boolean"
           },
           "parameters": {
            "type": "object"
           },
           "description": {
            "type": "string"
           }
          }
         }
        }
       },
       "description": "Client-executed function definitions; return results using role=tool and tool_call_id."
      },
      "top_k": {
       "type": "integer",
       "description": "Model-supported top_k; see /docs/llm-capabilities.md."
      },
      "top_p": {
       "type": "number",
       "description": "Model-supported top_p; see /docs/llm-capabilities.md."
      },
      "stream": {
       "type": "boolean",
       "description": "Return live OpenAI-compatible SSE after payment settlement."
      },
      "messages": {
       "type": "array",
       "items": {
        "type": "object",
        "anyOf": [
         {
          "required": [
           "content"
          ]
         },
         {
          "required": [
           "tool_calls"
          ]
         }
        ],
        "required": [
         "role"
        ],
        "properties": {
         "name": {
          "type": "string"
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "model": "kwaipilot/kat-coder-pro-v2.5",
  "choices": [
   {
    "index": 0,
    "message": {
     "role": "assistant",
     "content": "Hello!"
    },
    "finish_reason": "stop"
   }
  ],
  "content": "Hello!"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402engine-kat-coder-pro-v2-5-llm-62d82e36/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402engine.app](https://www.zero.xyz/host/x402engine.app/llms.txt)