apistack-sdk

Official JavaScript client for APIStack: 100+ production APIs (email and phone validation, business days and holidays, loan and mortgage calculators, DNS/SSL/WHOIS, reference data, AI text tools) behind one API key. Free plan: 1,000 calls/month.

npm install apistack-sdk

import { APIStack } from 'apistack-sdk'

const apistack = new APIStack() // reads APISTACK_API_KEY

const email = await apistack.post('/api/utilities/email-address-validator/v1', { email: '[email protected]' })
console.log(email.data.isValid, email.data.typoSuggestion) // false { suggestion: 'gmail.com', ... }

const loan = await apistack.get('/api/finance/loan-calculator/v1/payment', { principal: 350000, rate: 6.5, term: 30 })
console.log(loan.paymentCalculation.monthlyPayment) // 2212.24

Every API's path, parameters and a live tester are in the catalog. Errors throw APIStackError with status, code and the response body. 429 and 5xx responses are retried with backoff (maxRetries, default 2).

AI agents: you don't need this package. Connect the MCP server at https://apistack.online/api/mcp/connect instead (setup).