If you've ever needed an AI agent to validate a WhatsApp number, build a wa.me
link, or generate a QR code on the fly, you've probably hand-rolled it: scrape a regex off Stack Overflow, write your own phone-format validator, maybe hit some undocumented endpoint. We got tired of watching that happen and shipped a small, open MCP server that does it directly.
WhatsUsernames.link already runs a free public REST API for validating WhatsApp usernames/phone numbers and generating wa.me
links + QR codes. We just exposed the same logic over the Model Context Protocol, so Claude, and any other MCP client, can call it as native tools instead of you writing a fetch wrapper.
Endpoint:
https://whatsusernames.link/api/mcp
No API key. No account. No signup form. Same open, IP-rate-limited model as the REST API (60 req/min for JSON tools, 20 req/min for QR generation, sliding window via Upstash Redis).
| Tool | What it does |
|---|---|
validate_username |
|
Checks WhatsApp username (@username ) format |
|
validate_phone |
|
| Checks phone number format (8–15 digits, international) | |
username_link |
|
Builds a wa.me link (+ short link) from a username, optional prefilled text |
|
phone_link |
|
Builds a wa.me link from a phone number, optional prefilled text |
|
qr_code |
|
Renders a QR code (PNG or SVG) for a wa.me link, custom size/colors |
Every tool wraps the exact same services/
and validate-*
functions the REST API uses — there's no separate business logic to drift out of sync. If the REST endpoint says a number is valid, the MCP tool agrees, because it's the same code path.
Drop this into your MCP client config:
{
"mcpServers": {
"whatsusernames": {
"url": "https://whatsusernames.link/api/mcp"
}
}
}
That's it. No stdio process to spawn, no local install — it's a stateless Streamable HTTP transport running on Vercel, same domain as the site.
Two reasons.
Practical: every agent that needs to hand a user a "message me on WhatsApp" link ends up reimplementing username/phone validation and QR generation, badly, from scratch. That's a solved problem now — call the tool instead.
Strategic: we think a lot of AI-agent traffic is going to route through MCP servers the same way search traffic routes through APIs today. Being an early, documented, zero-friction MCP endpoint in the WhatsApp-tooling space is a cheap way to be the thing an agent reaches for, rather than something it reinvents.
Deliberately scoped down:
stdio
/local package distribution — remote HTTP only, for now.bsuid
parsing, webhook normalization) — those are more niche and will only get built if there's real demand for the current five.If you build something with it — or find an edge case it doesn't handle — we'd like to hear about it.
WhatsUsernames.link is a free tool for validating WhatsApp usernames/numbers and generating wa.me links and QR codes. REST API and MCP server are both public and free to use.