# Watt Chat Completions (Qwen3.5 4B / Qwen3 1.7B / 0.6B)

> Watt Chat Completions (Qwen3.5 4B / Qwen3 1.7B / 0.6B) is a paid API for AI agents from watt.area21.io, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-21).

Runs OpenAI-compatible chat completions using Qwen3 small language models on Watt's own infrastructure, billed per call in USDC via x402.

## Facts

- Endpoint: POST https://watt.area21.io/v1/chat/completions?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/watt-chat-completions-qwen3-5-4b-qwen3-1-7b-0-6b-838a90bf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zLfeSgWJKbTo9et0pyvoE

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 watt-chat-completions-qwen3-5-4b-qwen3-1-7b-0-6b-838a90bf -d '<json body>'
```

Example prompt: Using the Watt Qwen3.5 4B model, generate a reply to this customer message: 'Can you explain how compound interest works in simple terms?' — set max_tokens to 300.

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call OpenAI-compatible chat completion API without a monthly subscription, especially when using USDC on-chain payments (x402 protocol) or when specifically needing Qwen3-family small models (0.6B–4B) for cost-efficient inference tasks.

## Known failure modes

- Insufficient USDC balance causes payment failure and 402 response
- max_tokens too large relative to available budget
- Unsupported model name returns 400 or 422 error
- Malformed messages array causes validation error
- Rate limiting or capacity issues on Watt's fleet return 429 or 503

## Output

Returns an OpenAI-compatible chat completion object containing the assistant's generated message, finish reason, and token usage breakdown (prompt tokens, completion tokens, total tokens).

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/watt-chat-completions-qwen3-5-4b-qwen3-1-7b-0-6b-838a90bf/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from watt.area21.io](https://www.zero.xyz/host/watt.area21.io/llms.txt)