# 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).

Sends a message to a specific thread on the402.ai platform via the x402 payment protocol

## Facts

- Endpoint: POST https://api.the402.ai/v1/threads/thread_5e9fe506b6c04fe6/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-fd74e4b3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_sOghfV-m7o2DjV25ZQ25Z

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-fd74e4b3 -d '<json body>'
```

Example prompt: Send a message to my thread on the402 saying 'Please summarize the latest quarterly report' — use thread ID thread_5e9fe506b6c04fe6.

## When to prefer this

Use this endpoint when you need to post a message to an existing thread on the402.ai platform and have a valid thread ID. It is free with an API key (despite the $0.001 USDC x402 price tag, it is marked free with key), making it suitable for conversational AI workflows, automated messaging pipelines, and agent-to-thread communication on the402 infrastructure.

## Known failure modes

- Invalid or missing API key returns 401 unauthorized
- Thread ID not found or inaccessible returns 404
- Malformed message body returns 400 bad request
- Payment failure via x402 protocol returns 402
- Rate limiting or quota exceeded returns 429
- Network timeout if the platform is under load

## How this service works

Send thread message (free with API key)

## Output

Returns a confirmation that the message was posted to the specified thread, including the message ID, thread ID, and timestamp of delivery.

## 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-fd74e4b3/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)