# Fastsend SMS & Email Messaging API

> Fastsend SMS & Email Messaging API is a paid API for AI agents from fastsend.dev, paid per call via x402, $0.165/call, status unknown (last checked 2026-09-14).

Send an SMS text message or email to a recipient via the Fastsend messaging platform.

## Facts

- Endpoint: POST https://fastsend.dev/api/messages
- Price: $0.165/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastsend-sms-email-messaging-api-262c1939
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_85_MK0qxFX0ELftNNxiEI

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 fastsend-sms-email-messaging-api-262c1939 -d '<json body>'
```

Example prompt: Send an SMS via Fastsend to +12125550199 from +18005550100 saying 'Your order #4821 has shipped and will arrive by Friday.'

## When to prefer this

Choose this endpoint when an AI agent needs to programmatically send a single SMS or email notification and can pay per-message in USDC via the x402 protocol. It is well-suited for transactional alerts, confirmations, or one-off notifications where no existing messaging infrastructure is in place. Prefer this over higher-volume bulk messaging services when simplicity and per-call billing are acceptable.

## Known failure modes

- Invalid or unformatted phone number for SMS channel
- Invalid email address format
- Missing required fields (to, from, channel, content)
- Insufficient USDC balance to cover $0.165 per-call cost
- Unsupported channel value (not 'sms' or 'email')
- Missing subject field when channel is email
- Payment failure via x402 protocol

## How this service works

Send an SMS or email message via Fastsend.

## Output

A confirmation response indicating whether the SMS or email message was successfully dispatched by Fastsend, typically including delivery status or a message ID.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "to": {
   "type": "string"
  },
  "from": {
   "type": "string"
  },
  "channel": {
   "enum": [
    "sms",
    "email"
   ],
   "type": "string"
  },
  "content": {
   "type": "string"
  },
  "subject": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastsend-sms-email-messaging-api-262c1939/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fastsend.dev](https://www.zero.xyz/host/fastsend.dev/llms.txt)