JavaScript/TypeScript SDK

Complete reference for the SecureLend TypeScript/JavaScript SDK.

Installation

npm install @securelend/sdk

Initialization

Basic Setup

import { SecureLend } from "@securelend/sdk";

// Connects to https://mcp.securelend.ai/mcp by default
const securelend = new SecureLend();

Custom Configuration

import { SecureLend } from "@securelend/sdk";

const securelend = new SecureLend({
  serverUrl: "https://custom-mcp-server.com/mcp", // Optional
  timeout: 30000, // 30 seconds, default: 10000
  retries: 3, // Number of retries, default: 2
});

Most users should use the default configuration. Custom server URLs are for advanced use cases only.

TypeScript Support

The SDK includes complete TypeScript definitions:

import {
  SecureLend,
  BusinessLoanRequest,
  LoanComparisonResponse,
  LoanOffer,
  MortgageCalculationRequest,
  MortgagePaymentResponse,
} from "@securelend/sdk";

// Type-safe requests
const request: BusinessLoanRequest = {
  loanAmount: 200000,
  purpose: "equipment",
  annualRevenue: 1200000,
};

// Type-safe responses
const response: LoanComparisonResponse =
  await securelend.compareBusinessLoans(request);

// Access typed properties
const bestOffer: LoanOffer = response.offers[0];
console.log(bestOffer.interestRate); // Type: number
console.log(bestOffer.lenderName); // Type: string

API Reference

Loan Comparison Methods

compareBusinessLoans()

Compare business loan offers.

const result = await securelend.compareBusinessLoans({
  loanAmount: 200000, // Required: $1,000+
  purpose: "equipment", // Required: string
  annualRevenue: 1200000, // Optional: business revenue
  industry: "technology", // Optional: business industry
  state: "CA", // Optional: 2-letter state code
  creditScore: 720, // Optional: 300-850
});

// Returns
interface LoanComparisonResponse {
  offers: LoanOffer[];
  sessionId: string;
  timestamp: string;
}

interface LoanOffer {
  offerId: string;
  lenderName: string;
  productName: string;
  interestRate: number;
  monthlyPayment: number;
  termMonths: number;
  loanAmount: number;
  approvalLikelihood?: number;
  originationFee?: number;
  prepaymentPenalty?: boolean;
}

comparePersonalLoans()

Compare personal loan offers.

const result = await securelend.comparePersonalLoans({
  loanAmount: 25000, // Required: $1,000-$100,000
  purpose: "debt_consolidation", // Required: enum
  creditScore: 720, // Optional: 300-850
  employmentStatus: "employed", // Optional: enum
  monthlyIncome: 5000, // Optional: USD
  state: "CA", // Optional: 2-letter code
});

// Purpose options
type LoanPurpose =
  | "debt_consolidation"
  | "home_improvement"
  | "major_purchase"
  | "medical"
  | "vacation"
  | "other";

// Employment status options
type EmploymentStatus = "employed" | "self_employed" | "retired" | "unemployed";

compareCarLoans()

Compare auto loan rates.

const result = await securelend.compareCarLoans({
  loanAmount: 35000, // Required: $1,000-$100,000
  isNew: true, // Required: new or used vehicle
  creditScore: 750, // Optional: 300-850
  state: "CA", // Optional: 2-letter state code
});

compareStudentLoans()

Compare student loan options.

const result = await securelend.compareStudentLoans({
  loanAmount: 50000, // Required: $1,000-$250,000
  degreeType: "graduate", // Required: enum
  creditScore: 680, // Optional: 300-850
  coSignerCreditScore: 750, // Optional: 300-850
  state: "CA", // Optional: 2-letter code
});

// Degree type options
type DegreeType = "undergraduate" | "graduate" | "mba" | "medical" | "law";

comparePersonalMortgages()

Compare mortgage rates for home purchases.

const result = await securelend.comparePersonalMortgages({
  loanAmount: 320000, // Required: $50,000-$2,000,000
  loanType: "conventional", // Required: enum
  homePrice: 400000, // Optional: property value
  downPayment: 80000, // Optional: down payment amount
  creditScore: 720, // Optional: 500-850
  propertyType: "primary", // Optional: enum
  state: "CA", // Optional: 2-letter code
});

// Loan type options
type MortgageLoanType = "conventional" | "fha" | "va" | "jumbo" | "refinance";

// Property type options
type PropertyType = "primary" | "secondary" | "investment";

Calculator Methods

calculateLoanPayment()

Calculate monthly payment for any loan.

const result = await securelend.calculateLoanPayment({
  loanAmount: 200000, // Required: loan principal
  interestRate: 7.5, // Required: annual rate (e.g., 7.5 for 7.5%)
  loanTermInMonths: 60, // Required: term in months
});

// Returns
interface LoanCalculation {
  monthlyPayment: number;
  totalInterest: number;
  totalAmount: number;
  amortizationSchedule?: Array<{
    month: number;
    payment: number;
    principal: number;
    interest: number;
    balance: number;
  }>;
}

calculateMortgagePayment()

Calculate PITI (Principal, Interest, Taxes, Insurance) mortgage payment.

const result = await securelend.calculateMortgagePayment({
  propertyValue: 400000, // Required: property value
  downPayment: 80000, // Required: down payment
  interestRate: 6.5, // Required: annual rate
  loanTermInYears: 30, // Required: term in years
  propertyTaxRate: 1.2, // Required: annual tax rate %
  homeInsurance: 1500, // Required: annual insurance cost
});

// Returns
interface MortgagePaymentResponse {
  monthlyPayment: number; // Total PITI payment
  principalAndInterest: number; // P&I portion
  propertyTaxes: number; // Monthly taxes
  insurance: number; // Monthly insurance
  loanAmount: number; // Calculated loan amount
  totalInterest: number; // Over life of loan
}

compareLeaseVsPurchase()

Compare total costs of leasing vs buying a vehicle.

const result = await securelend.compareLeaseVsPurchase({
  purchasePrice: 35000, // Required: vehicle price
  downPayment: 5000, // Required: purchase down payment
  interestRate: 6.0, // Required: purchase loan rate
  loanTermInMonths: 60, // Required: purchase term
  monthlyLeasePayment: 450, // Required: lease payment
  leaseTermInMonths: 36, // Required: lease term
  moneyFactor: 0.0025, // Required: lease money factor
  residualValuePercentage: 55, // Required: 0-100
  salesTaxRate: 7.5, // Required: tax rate %
  expectedOwnershipInMonths: 60, // Required: how long keeping vehicle
  acquisitionFee: 595, // Optional: lease acquisition fee
  securityDeposit: 0, // Optional: lease security deposit
});

// Returns
interface LeaseVsPurchaseResponse {
  leaseTotalCost: number;
  purchaseTotalCost: number;
  costDifference: number;
  recommendation: "lease" | "purchase";
  breakEvenMonth: number;
}

Banking & Credit Card Methods

comparePersonalBanking()

Compare checking and savings accounts.

const result = await securelend.comparePersonalBanking({
  features: [
    // Optional: desired features
    "no_monthly_fees",
    "high_interest",
    "mobile_deposit",
    "atm_access",
  ],
});

compareBusinessBanking()

Compare business banking products.

const result = await securelend.compareBusinessBanking({
  industry: "technology", // Optional: business industry
  monthlyTransactions: 200, // Optional: estimated transactions
});

compareSavingsAccounts()

Compare high-yield savings accounts.

const result = await securelend.compareSavingsAccounts({
  initialDeposit: 10000, // Optional: starting balance
});

comparePersonalCreditCards()

Compare personal credit card offers.

const result = await securelend.comparePersonalCreditCards({
  creditScore: 750, // Optional: 300-850
  rewardsType: "cash_back", // Optional: rewards preference
});

// Rewards type options
type RewardsType = "cash_back" | "travel" | "points";

compareBusinessCreditCards()

Compare business credit card options.

const result = await securelend.compareBusinessCreditCards({
  creditScore: 720, // Optional: 300-850
  annualRevenue: 1000000, // Optional: business revenue
  businessAgeInYears: 3, // Optional: years in business
});

Application Management Methods

Application methods handle sensitive user data. Always obtain explicit user consent before calling these methods.

getOffer()

Submit application to one selected lender.

const result = await securelend.getOffer({
  applicant: {
    firstName: "John",
    lastName: "Doe",
    email: "john@example.com",
    phone: "+1-555-0100", // Optional
  },
  applicationData: {
    // Original loan search parameters
    loanAmount: 200000,
    purpose: "equipment",
    // ... other parameters
  },
  productType: "BUSINESS_LOAN", // Enum: see below
  provider: {
    providerId: "provider-123",
    providerName: "ABC Business Capital",
  },
});

// Product type options
type ProductType =
  | "INSTALLMENT_LOAN"
  | "LINE_OF_CREDIT"
  | "SHORT_TERM_CREDIT"
  | "BNPL"
  | "MORTGAGE"
  | "AUTO_LOAN"
  | "AUTO_REFINANCE"
  | "STUDENT_LOAN"
  | "STUDENT_LOAN_REFINANCE"
  | "BUSINESS_LOAN"
  | "BUSINESS_BANKING"
  | "BUSINESS_CREDIT_CARD"
  | "PERSONAL_BANKING"
  | "SAVINGS_ACCOUNT"
  | "PERSONAL_CREDIT_CARD";

trackOfferStatus()

Check status of submitted applications.

// By application ID
const status = await securelend.trackOfferStatus({
  applicationId: "app-123",
});

// Or by email (returns all applications)
const statuses = await securelend.trackOfferStatus({
  email: "john@example.com",
});

Error Handling

The SDK throws typed errors for different failure scenarios:

import { SecureLend, SecureLendError } from "@securelend/sdk";

const securelend = new SecureLend();

try {
  const loans = await securelend.compareBusinessLoans({
    loanAmount: 200000,
    purpose: "equipment",
  });

  console.log(`Found ${loans.offers.length} offers`);
} catch (error) {
  if (error instanceof SecureLendError) {
    // Structured SecureLend error
    console.error("Error Code:", error.code);
    console.error("Message:", error.message);
    console.error("Details:", error.details);

    // Common error codes
    switch (error.code) {
      case "INVALID_PARAMETER":
        // Handle validation error
        break;
      case "RATE_LIMIT_EXCEEDED":
        // Handle rate limit
        break;
      case "SERVICE_UNAVAILABLE":
        // Handle service outage
        break;
      case "NETWORK_ERROR":
        // Handle network issues
        break;
    }
  } else {
    // Unexpected error
    console.error("Unexpected error:", error);
  }
}

Error Types

interface SecureLendError extends Error {
  code: ErrorCode;
  message: string;
  details?: Record<string, any>;
  statusCode?: number;
}

type ErrorCode =
  | "INVALID_PARAMETER"
  | "RATE_LIMIT_EXCEEDED"
  | "SERVICE_UNAVAILABLE"
  | "NETWORK_ERROR"
  | "TIMEOUT"
  | "PROVIDER_ERROR"
  | "AUTHENTICATION_ERROR";

Platform-Specific Usage

Node.js

Works natively in Node.js 16+:

import { SecureLend } from "@securelend/sdk";

const securelend = new SecureLend();
const loans = await securelend.compareBusinessLoans({
  loanAmount: 200000,
  purpose: "equipment",
});

Next.js

API Routes

// app/api/compare-loans/route.ts
import { SecureLend } from "@securelend/sdk";
import { NextResponse } from "next/server";

export async function POST(request: Request) {
  const body = await request.json();

  const securelend = new SecureLend();

  try {
    const result = await securelend.compareBusinessLoans({
      loanAmount: body.amount,
      purpose: body.purpose,
      annualRevenue: body.revenue,
    });

    return NextResponse.json(result);
  } catch (error) {
    console.error("Loan comparison failed:", error);
    return NextResponse.json(
      { error: "Failed to compare loans" },
      { status: 500 },
    );
  }
}

Server Components

// app/loans/page.tsx
import { SecureLend } from '@securelend/sdk';

export default async function LoansPage() {
  const securelend = new SecureLend();

  const loans = await securelend.compareBusinessLoans({
    loanAmount: 200000,
    purpose: 'equipment'
  });

  return (
    <div>
      <h1>Loan Offers</h1>
      {loans.offers.map(offer => (
        <div key={offer.offerId}>
          <h2>{offer.lenderName}</h2>
          <p>{offer.interestRate}% APR</p>
        </div>
      ))}
    </div>
  );
}

React (Client-Side)

import { useState, useEffect } from 'react';
import { SecureLend } from '@securelend/sdk';

function LoanComparison() {
  const [offers, setOffers] = useState([]);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    const securelend = new SecureLend();

    securelend.compareBusinessLoans({
      loanAmount: 200000,
      purpose: 'equipment'
    })
    .then(result => {
      setOffers(result.offers);
      setLoading(false);
    })
    .catch(console.error);
  }, []);

  if (loading) return <div>Loading...</div>;

  return (
    <div>
      {offers.map(offer => (
        <LoanCard key={offer.offerId} offer={offer} />
      ))}
    </div>
  );
}

Edge Runtime (Vercel, Cloudflare Workers)

The SDK works in edge runtimes:

// Edge API route
import { SecureLend } from "@securelend/sdk";

export const config = {
  runtime: "edge",
};

export default async function handler(req: Request) {
  const securelend = new SecureLend();

  const loans = await securelend.compareBusinessLoans({
    loanAmount: 200000,
    purpose: "equipment",
  });

  return new Response(JSON.stringify(loans), {
    headers: { "Content-Type": "application/json" },
  });
}

Rate Limits

Comparison Tools: 100 requests per minute per IP
Application Tools: 10 requests per minute per email The SDK automatically handles rate limiting with exponential backoff.

const securelend = new SecureLend({
  retries: 3, // Retry up to 3 times on rate limit
  timeout: 30000, // 30 second timeout
});

Best Practices

1. Reuse Client Instances

// ✅ Good: Create once, reuse
const securelend = new SecureLend();

async function compareLoans() {
  return securelend.compareBusinessLoans({ ... });
}

// ❌ Bad: Create new instance each time
async function compareLoans() {
  const securelend = new SecureLend();
  return securelend.compareBusinessLoans({ ... });
}

2. Handle Errors Gracefully

try {
  const loans = await securelend.compareBusinessLoans({ ... });
  return loans;
} catch (error) {
  if (error instanceof SecureLendError) {
    // Log structured error
    logger.error('Loan comparison failed', {
      code: error.code,
      details: error.details
    });
  }
  // Return fallback or rethrow
  throw error;
}

3. Use TypeScript Types

import { BusinessLoanRequest, LoanComparisonResponse } from "@securelend/sdk";

async function getLoans(
  request: BusinessLoanRequest,
): Promise<LoanComparisonResponse> {
  const securelend = new SecureLend();
  return securelend.compareBusinessLoans(request);
}

4. Validate Input Early

function validateLoanRequest(amount: number, purpose: string) {
  if (amount < 1000 || amount > 5000000) {
    throw new Error("Loan amount must be between $1,000 and $5,000,000");
  }

  const validPurposes = ["equipment", "working_capital", "expansion"];
  if (!validPurposes.includes(purpose)) {
    throw new Error(`Invalid purpose: ${purpose}`);
  }
}

Next Steps

Code Examples

Practical examples and patterns

Tool Reference

All 20 tools documented

GitHub Repository

View source and contribute

Support

Get help from our team

Getting Started

Platform

Platform (Advanced)

SDKs

MCP Integrations

APIs

Guides

​JavaScript/TypeScript SDK

​Installation

​Initialization

​Basic Setup

​Custom Configuration

​TypeScript Support

​API Reference

​Loan Comparison Methods

​compareBusinessLoans()

​comparePersonalLoans()

​compareCarLoans()

​compareStudentLoans()

​comparePersonalMortgages()

​Calculator Methods

​calculateLoanPayment()

​calculateMortgagePayment()

​compareLeaseVsPurchase()

​Banking & Credit Card Methods

​comparePersonalBanking()

​compareBusinessBanking()

​compareSavingsAccounts()

​comparePersonalCreditCards()

​compareBusinessCreditCards()

​Application Management Methods

​getOffer()

​trackOfferStatus()

​Error Handling

​Error Types

​Platform-Specific Usage

​Node.js

​Next.js

​API Routes

​Server Components

​React (Client-Side)

​Edge Runtime (Vercel, Cloudflare Workers)

​Rate Limits

​Best Practices

​1. Reuse Client Instances

​2. Handle Errors Gracefully

​3. Use TypeScript Types

​4. Validate Input Early

​Next Steps

Code Examples

Tool Reference

GitHub Repository

Support

JavaScript/TypeScript SDK

Installation

Initialization

Basic Setup

Custom Configuration

TypeScript Support

API Reference

Loan Comparison Methods

compareBusinessLoans()

comparePersonalLoans()

compareCarLoans()

compareStudentLoans()

comparePersonalMortgages()

Calculator Methods

calculateLoanPayment()

calculateMortgagePayment()

compareLeaseVsPurchase()

Banking & Credit Card Methods

comparePersonalBanking()

compareBusinessBanking()

compareSavingsAccounts()

comparePersonalCreditCards()

compareBusinessCreditCards()

Application Management Methods

getOffer()

trackOfferStatus()

Error Handling

Error Types

Platform-Specific Usage

Node.js

Next.js

API Routes

Server Components

React (Client-Side)

Edge Runtime (Vercel, Cloudflare Workers)

Rate Limits

Best Practices

1. Reuse Client Instances

2. Handle Errors Gracefully

3. Use TypeScript Types

4. Validate Input Early

Next Steps