SMS Validator API
Validate SMS-capable phone numbers -- mobile vs landline detection, carrier type, E.164 format, SMS readiness. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.
Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.
Quickstart -- MCP
Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):
{
"mcpServers": {
"sms-validator": {
"url": "https://sms-validator.api.klymax402.com/mcp"
}
}
}
Quickstart -- HTTP (x402)
curl -X POST "https://sms-validator.api.klymax402.com/api/validate" \
-H "Content-Type: application/json" \
-d '{"phone":"..."}'
# -> 402 Payment Required, with an x402 payment challenge in the response body
Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.
Tools
| Tool | Method | Path | Price | Description |
|---|---|---|---|---|
sms_validate_number | POST | /api/validate | $0.005 | Validate if a phone number can receive SMS |
sms_validate_number
Use this when you need to check if a phone number can receive SMS messages. Returns SMS capability data in JSON.
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
phone | string | yes | Phone number with country code (e.g. +14155551234) |
countryCode | string | no | ISO 3166-1 alpha-2 country code hint (e.g. US, FR, GB) |
Example response:
{"phone":"+14155551234","canReceiveSMS":true,"carrierType":"mobile","e164":"+14155551234","countryCode":"US","numberType":"mobile","carrier":"T-Mobile"}
When to use: sending SMS campaigns, FOR filtering landlines from SMS lists, verifying 2FA phone numbers, and OTP delivery validation.
Not for: full phone validation with carrier lookup (use phone_validate_number), email validation (use email_verify_address), address validation (use address_validate).
Example agent prompts
- "Check if a phone number can receive SMS messages"
Payment
- Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
- Network: Base L2 (
eip155:8453) - Asset: USDC
- Facilitator: Coinbase CDP (primary), PayAI (fallback)
- Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)
Part of klymax402
100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.
- Catalog: https://klymax402.com/llms.txt
- Full API reference: https://klymax402.com/llms-full.txt
- Live stats: https://klymax402.com/stats
License
MIT