Simple Developer Platform · invite-only early access

Stop maintaining the plumbing.

Email verification, a developer MCP, and a public-holiday API: the load-bearing infrastructure every app re-implements. One key. One metered bill.

We'll send your API key when a slot opens.

curl -X POST https://dev-api.meetsimple.co/v1/email/verify \
  -H "Authorization: Bearer sk_live_••••••••••••" \
  -H "Content-Type: application/json" \
  -d '{"email": "sales@example.com"}'

import { createDevApiClient } from "@simple/dev-api-sdk";

const client = createDevApiClient({ apiKey: "sk_live_••••••••••••" });

const result = await client.email.verify({
  email: "sales@example.com",
});

import httpx

response = httpx.post(
    "https://dev-api.meetsimple.co/v1/email/verify",
    headers={"Authorization": "Bearer sk_live_••••••••••••"},
    json={"email": "sales@example.com"},
)
data = response.json()

Response

{
  "email": "sales@example.com",
  "domain": "example.com",
  "tier": "risky",
  "reason": "role_account",
  "signals": {
    "syntaxValid": true,
    "hasMx": true,
    "disposableDomain": false,
    "freeProvider": false,
    "roleAccount": true
  }
}

Illustrative · not a live request

Invite-only early access · email verification + a developer MCP · one key, one metered bill

How it works

01
Get a key

Join the waitlist. When a slot opens, you'll receive one API key that covers every surface: email, MCP, and holidays.
Authorization: Bearer sk_live_…
02
Call an endpoint

Use the SDK, the REST endpoints, or point your AI agent at the MCP server. They all run off the same key and the same quota.
POST /v1/email/verify
03
One metered bill

Every request across every surface lands on a single Polar subscription. Usage warnings fire at 80 % of your quota so nothing cuts out without notice.
dev-api-usage · metered

What's in the platform

Three APIs. One key. The same metered bill.

POST /v1/email/verify

Email Verification API

Checks syntax, MX records via DoH, disposable-domain lists, role-account patterns, and whether the domain is a free provider. Returns a tier (risky, unknown, or invalid) and the signals behind it.

Catch-all and accept-all domains return risky or unknown: we won't claim an inbox exists when the domain can't prove it.

POST /mcp

Developer MCP API

A first-party Model Context Protocol server, shipped and running today. Point your AI agent at /mcp and it gets the same tools, authenticated, quota-governed, and metered identically to the REST endpoints.

Streamable-HTTP transport. Your existing API key is the only credential needed.

GET /v1/holidays/{country}/{year} preview

Public Holiday API

Timezone-aware nationwide public-holiday lookups, plus business-day arithmetic: add business days, check whether a date is a working day, and calculate days between two dates. A bundled data sample is live now; the full licensed dataset ships later.

Preview: fixed nationwide dates only. Moving holidays and regional subdivisions arrive with the full dataset.

Usage-metered. One bill.

Pricing tiers are coming. Here is how the model works today.

Metered by request: Every call to every surface increments the same usage counter. No separate quotas per API.
Warned before you're capped: Usage warnings fire at 80 % and 100 % of your quota. Requests are declined at the hard cap. Nothing drops silently.
One Polar subscription: All API meters (email, MCP, and holidays) roll up to a single subscription. No juggling separate invoices.

Exact pricing tiers are not yet published. Early-access members will receive details before billing is activated.

What it replaces

→ @simple/dev-api-sdk covers every surface. One import, typed sub-clients for email, holidays, and identity.
→ Honest email tiers. We return what we know: risky, unknown, or invalid. No made-up verification figures.
→ Business-day arithmetic built in. Add business days, check working days, and calculate intervals. Holiday-aware and timezone-aware.
→ One key, one console, one bill. No per-API juggling, no separate accounts, no separate invoices.

Data handling. Email addresses submitted to the verification API are processed in-flight and not stored after the response is returned. Waitlist signups store your email address only to send your API key when a slot opens. All API requests are rate-limited and quota-bounded per key. Full privacy policy →

Request early access

Leave your email. We'll send your API key when a slot opens. No credit card required.

Invite-only early access · one API key · one metered bill