# Qwen3.5 LLM API (x402 Gateway)

> Qwen3.5 LLM API (x402 Gateway) is a paid API for AI agents from x402-gateway-production.up.railway.app, paid per call via x402, $0.006000/call, status unknown (last checked 2026-09-14, last successful call 2026-06-17).

Calls Alibaba's Qwen3.5 large language model with 1M context window for multilingual text and coding tasks via pay-per-call x402 gateway

## Facts

- Endpoint: POST https://x402-gateway-production.up.railway.app/api/llm/qwen3.5
- Price: $0.006000/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Last successful call: 2026-06-17
- Success rate: 10% of calls made through Zero
- Activations on Zero: 10
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-gateway-production-up-railway-app-95f647a8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_A7L0YIMWh7EeNlpVvhwm8

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 x402-gateway-production-up-railway-app-95f647a8 -d '<json body>'
```

Example prompt: Use Qwen3.5 to write a Python function that parses ISO 8601 dates and explain how it handles edge cases — the context includes a 50,000-token codebase I've pasted in.

## When to prefer this

Choose this endpoint when you need a large-context LLM (up to 1M tokens), need strong multilingual capabilities (especially East Asian languages), or want Alibaba's Qwen model specifically as an alternative to OpenAI/Anthropic models. Useful for processing very long documents or codebases in a single call.

## Known failure modes

- Payment not attached or insufficient USDC — 402 Payment Required
- Prompt exceeds 1M token context limit — context length error
- Model unavailable or gateway timeout — 503 or 504 error
- Malformed request body — 400 Bad Request
- Rate limit exceeded — 429 Too Many Requests

## How this service works

Alibaba's latest model — 1M context, strong multilingual and coding capabilities

## Output

Returns the model-generated text completion, code, translation, or reasoning output from Alibaba's Qwen3.5 model, which supports up to 1 million tokens of context and excels at multilingual and software engineering tasks.

## Example request

```json
{
 "messages": [
  {
   "role": "user",
   "content": "Hello"
  }
 ]
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-gateway-production-up-railway-app-95f647a8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-gateway-production.up.railway.app](https://www.zero.xyz/host/x402-gateway-production.up.railway.app/llms.txt)