# DeepSeek V4 Flash Chat Completions via x402 (x402donghang)

> DeepSeek V4 Flash Chat Completions via x402 (x402donghang) is a paid API for AI agents from x402donghang.duckdns.org, paid per call via x402, $0.003/call, status down (last checked 2026-10-19).

Runs a DeepSeek V4 Flash chat completion request via an OpenAI-compatible API, billed at $0.003 USDC per call using the x402 payment protocol — no signup required.

## Facts

- Endpoint: POST https://x402donghang.duckdns.org/x402/v1/models/deepseek-v4-flash/chat/completions?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: down
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/deepseek-v4-flash-chat-completions-via-x402-x402donghang-aafdfccb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Qjhzwubb4taBn1AvtXk_Z

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 deepseek-v4-flash-chat-completions-via-x402-x402donghang-aafdfccb -d '<json body>'
```

Example prompt: Ask DeepSeek V4 Flash to explain the difference between proof-of-work and proof-of-stake in simple terms — keep the response under 300 tokens.

## When to prefer this

Choose this endpoint when you need a low-cost ($0.003/call), no-signup, pay-as-you-go LLM for chat completions that is OpenAI-compatible and settles instantly via USDC on x402. It is ideal for AI agents that need to avoid subscription lock-in, prototype quickly with crypto micropayments, or embed inference steps inside automated pipelines without credential management overhead. Prefer alternatives if you need GPT-4-class reasoning, image inputs, or function calling.

## Known failure modes

- Payment not included or insufficient USDC — returns HTTP 402 with payment instructions
- Invalid or missing 'messages' array — returns 400 validation error
- Model field not set to 'deepseek-v4-flash' — may return 404 or model-not-found error
- Upstream DeepSeek service unavailable — returns 502 or 503
- max_tokens too large for model context — may truncate or return error
- Network timeout if streaming is enabled but client disconnects early

## How this service works

Fresh crypto narrative research with market context and verifiable source URLs. Free BTC sample; custom radar $0.02/call via x402 USDC.

## Output

Returns a standard OpenAI-compatible chat completion JSON object containing an 'id', 'model' (deepseek-v4-flash), 'object' (chat.completion), and a 'choices' array with the assistant's reply message, its role, content string, and a 'finish_reason' field (e.g. 'stop').

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Use \"deepseek-v4-flash\""
  },
  "stream": {
   "type": "boolean"
  },
  "messages": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "role",
     "content"
    ],
    "properties": {
     "role": {
      "type": "string"
     },
     "content": {
      "type": "string"
     }
    }
   }
  },
  "max_tokens": {
   "type": "number"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "chatcmpl-x402",
  "model": "deepseek-v4-flash",
  "object": "chat.completion",
  "choices": [
   {
    "index": 0,
    "message": {
     "role": "assistant",
     "content": "Hello!"
    },
    "finish_reason": "stop"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/deepseek-v4-flash-chat-completions-via-x402-x402donghang-aafdfccb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402donghang.duckdns.org](https://www.zero.xyz/host/x402donghang.duckdns.org/llms.txt)