# the402.ai Thread Message Sender

> the402.ai Thread Message Sender is a paid API for AI agents from api.the402.ai, paid per call via x402, $0.001/call, status down (last checked 2026-09-15).

Posts a new message to a specific AI thread on the402.ai platform, enabling conversational interactions within a persistent thread context

## Facts

- Endpoint: POST https://api.the402.ai/v1/threads/thread_8e346c6da4264b13/messages
- Price: $0.001/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-the402-ai-d4f53485
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_hasURP-2U2cAWqCft0eTC

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 api-the402-ai-d4f53485 -d '<json body>'
```

Example prompt: Send the message 'What are the top 3 trends in renewable energy in 2025?' to my the402.ai thread so I can continue the conversation I started earlier.

## When to prefer this

Use this endpoint when you need to append a user or system message to an existing persistent thread on the402.ai and want a pay-per-use micropayment model via x402 at $0.001 USDC per call. Prefer this over general messaging APIs when working within the the402.ai ecosystem and already have a valid thread ID.

## Known failure modes

- Invalid or missing API key returns 401 Unauthorized
- Thread ID not found returns 404 Not Found
- Malformed message body returns 400 Bad Request
- Insufficient payment or payment failure returns 402 Payment Required
- Rate limiting triggers 429 Too Many Requests
- Thread has been closed or archived returns 403 Forbidden

## How this service works

Send thread message (free with API key)

## Output

Returns a confirmation of the posted message, including the message ID, thread ID, timestamp, and message content as stored within the thread on the402.ai platform.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "id"
 ],
 "properties": {
  "id": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-the402-ai-d4f53485/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.the402.ai](https://www.zero.xyz/host/api.the402.ai/llms.txt)