# 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 2026-09-16).

Posts a new message to a specific thread on the the402.ai platform using an API key

## Facts

- Endpoint: POST https://api.the402.ai/v1/threads/thread_b4bd1ded4d674d36/messages
- Price: $0.001/call
- Payment: x402
- Status: down
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-the402-ai-384950e8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_JPHI9lqRwceYa1QhEpNCr

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-384950e8 -d '<json body>'
```

Example prompt: Send a message to thread ID thread_b4bd1ded4d674d36 on the402.ai saying 'Please confirm the order has been processed and provide a receipt.'

## When to prefer this

Use this endpoint when you need to send a message to an existing thread on the the402.ai platform and have a valid thread ID. This is suitable for agentic workflows where conversation threads are managed on the402.ai and you need to post follow-up messages, replies, or instructions. It is free with an API key, making it cost-effective for high-frequency messaging within threads.

## Known failure modes

- Missing or invalid thread ID returns an error (400 Bad Request)
- Invalid or missing API key results in authentication failure (401 Unauthorized)
- Thread not found returns 404
- Rate limiting or quota exceeded returns 429
- Malformed request body returns 400

## How this service works

Send thread message (free with API key)

## Output

A confirmation that the message was posted to the specified thread, likely including the message object or message ID, timestamp, and thread reference.

## 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-384950e8/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)