Project Synapse Developer API (v1)

Quickstart

Authenticate every request with your developer key:

Authorization: Bearer <your-api-key>

Example — public holidays for the United States in 2026:

curl https://dev-api.meetsimple.co/v1/holidays/US/2026 \
  -H "Authorization: Bearer <your-api-key>"

TypeScript SDK

Or call the API through the generated client:

npm install @simple/dev-api-sdk

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

const client = createDevApiClient({ apiKey: "<your-api-key>" });
const { data } = await client.holidays.list({ country: "US", year: 2026 });
const check = await client.email.verify({ email: "you@example.com" });
// check.data?.tier is "invalid" | "risky" | "unknown" — never a false "valid".

MCP server

Call the launch domains from a coding agent over the Model Context Protocol. Point your MCP client at the streamable-HTTP endpoint and authenticate with your developer key:

https://dev-api.meetsimple.co/mcp

{
  "mcpServers": {
    "project-synapse": {
      "url": "https://dev-api.meetsimple.co/mcp",
      "headers": { "Authorization": "Bearer <your-api-key>" }
    }
  }
}

Tools: holidays_list, working_hours_is_business_day, working_hours_add_business_days, working_hours_business_days_between, and email_verify. MCP calls are metered and quota-governed exactly like REST and SDK calls, and email_verify never returns a positive valid.

The full machine-readable contract is at /openapi.json.