# x402engine GLM-5.3 LLM API

> x402engine GLM-5.3 LLM API is a paid API for AI agents from x402engine.app, paid per call via x402, $0.011035/call, status unknown (last checked 2026-10-20).

Send OpenAI-compatible chat messages to Z-AI's GLM-5.3 language model and receive generated text responses, paid per-call via USDC micropayment.

## Facts

- Endpoint: POST https://x402engine.app/api/llm/glm-5.3?utm_source=zero.xyz
- Price: $0.011035/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402engine-glm-5-3-llm-api-7ca458d8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zzZuwOJhuU0BiCbnCFXom

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-glm-5-3-llm-api-7ca458d8 -d '<json body>'
```

Example prompt: Send this conversation to GLM-5.3 and get a response: system message is 'You are a helpful assistant', and the user asks 'Explain the difference between supervised and unsupervised learning in two paragraphs'.

## When to prefer this

Choose this endpoint when you need to call GLM-5.3 specifically (Z-AI's flagship model) without a subscription, paying only per-call in USDC. It is ideal for AI agents that need on-demand LLM inference with crypto-native payments, or for users wanting to compare GLM-5.3's outputs alongside other models available on the same platform. Prefer it over OpenAI or Anthropic endpoints when you want a Chinese-developed frontier model or need pay-as-you-go crypto billing on Base, MegaETH, or Solana.

## Known failure modes

- Payment not settled — HTTP 402 returned if micropayment header is missing or insufficient
- Invalid messages array — missing required 'role' or 'content'/'tool_calls' fields causes schema validation error
- Unsupported parameter — if a capability like logprobs or seed is not supported by GLM-5.3, it may be silently ignored or return an error (see /docs/llm-capabilities.md)
- Streaming misconfiguration — SSE stream only starts after payment settlement; network timeout before settlement causes failure
- Context length exceeded — very long message arrays may be rejected by the underlying model

## How this service works

x402engine — GLM-5.3 is a large-scale reasoning model from Z.ai, built for complex software engineering and long-horizon agent tasks. It supports text input and output with a 1M-token context window, and improves

## Output

An OpenAI-compatible JSON response containing the model name ('z-ai/glm-5.3'), a choices array with the assistant's message (role, content, and optional tool_calls), finish_reason, and a top-level 'content' shortcut field. Streaming mode returns SSE chunks instead.

## 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."
      },
      "logprobs": {
       "type": "boolean",
       "description": "Model-supported logprobs; see /docs/llm-capabilities.md."
      },
      "messages": {
       "type": "array",
       "items": {
        "type": "object",
        "anyOf": [
         {
          "required": [
           "content"
          ]
         },
         {
          "required": [
           "tool_calls"
          ]
    
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "model": "z-ai/glm-5.3",
  "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-glm-5-3-llm-api-7ca458d8/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)