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Package Installation

FundKit uses a modular architecture where you install only the packages you need.

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Core Package (Required)

The core package contains the main PaymentClient and shared functionality: 
npm install @fundkit/core

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Provider Packages (Choose what you need)

Install the specific payment providers you want to support:
bash npm install @fundkit/honeycoin Supports: Mobile money in Uganda, Kenya, Tanzania Features: Collections, payouts, status checking

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Type Definitions (Optional)

For enhanced TypeScript support: 
npm install @fundkit/types
The types package is automatically included when you install core or provider packages, but you can install it separately if you only need the type definitions.

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Environment Setup

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Node.js Requirements

FundKit supports the following Node.js versions: - Node.js 16.x (Minimum supported) - Node.js 18.x (Recommended) - Node.js 20.x (Latest LTS) - Node.js 22.x (Current)
Node.js versions below 16.x are not supported due to missing ESM and crypto features.
FundKit works in multiple JavaScript runtimes: - Node.js - Full support - Bun - Full support - Deno - Supported with import maps - Cloudflare Workers - Supported - Vercel Edge Functions - Supported - Browser - Core functionality only (no Node.js APIs)

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Environment Variables

Set up your environment variables for API keys and configuration:
.env
# FundKit Configuration
FUNDKIT_API_KEY=fk_test_your_sandbox_key_here
FUNDKIT_ENVIRONMENT=sandbox

# HoneyCoin (if using)
HONEYCOIN_API_KEY=your_honeycoin_api_key
HONEYCOIN_PUBLIC_KEY=your_honeycoin_public_key

# EasyPay (if using)
EASYPAY_SECRET=your_easypay_secret
EASYPAY_CLIENT_ID=your_easypay_client_id

# Tola (if using)
TOLA_API_KEY=your_tola_api_key
TOLA_MERCHANT_ID=your_tola_merchant_id
Use fk_test_ prefixed keys for sandbox testing. These work immediately without provider approval.

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Framework Integration

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Express.js

import express from 'express';
import { PaymentClient } from '@fundkit/core';
import { HoneyCoin } from '@fundkit/honeycoin';

const app = express();
app.use(express.json());

const paymentClient = new PaymentClient({
  apiKey: process.env.FUNDKIT_API_KEY!,
  providers: [
    new HoneyCoin({
      apiKey: process.env.HONEYCOIN_API_KEY!,
      publicKey: process.env.HONEYCOIN_PUBLIC_KEY!,
    }),
  ],
  environment: 'sandbox',
});

app.post('/payments', async (req, res) => {
  try {
    const result = await paymentClient.collection(req.body);
    res.json(result);
  } catch (error) {
    res.status(400).json({ error: error.message });
  }
});

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Next.js

import { NextRequest, NextResponse } from 'next/server';
import { PaymentClient } from '@fundkit/core';
import { HoneyCoin } from '@fundkit/honeycoin';

const paymentClient = new PaymentClient({
  apiKey: process.env.FUNDKIT_API_KEY!,
  providers: [
    new HoneyCoin({
      apiKey: process.env.HONEYCOIN_API_KEY!,
      publicKey: process.env.HONEYCOIN_PUBLIC_KEY!,
    }),
  ],
  environment: process.env.NODE_ENV === 'production' ? 'production' : 'sandbox',
});

export async function POST(request: NextRequest) {
  try {
    const transaction = await request.json();
    const result = await paymentClient.collection(transaction);
    return NextResponse.json(result);
  } catch (error) {
    return NextResponse.json({ error: error.message }, { status: 400 });
  }
}

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Fastify

import Fastify from 'fastify';
import { PaymentClient } from '@fundkit/core';
import { EasyPay } from '@fundkit/easypay';

const fastify = Fastify({ logger: true });

const paymentClient = new PaymentClient({
  apiKey: process.env.FUNDKIT_API_KEY!,
  providers: [
    new EasyPay({
      apiKey: process.env.EASYPAY_SECRET!,
      clientId: process.env.EASYPAY_CLIENT_ID!,
    }),
  ],
  environment: 'sandbox',
});

fastify.post('/payments', async (request, reply) => {
  try {
    const result = await paymentClient.collection(request.body);
    return result;
  } catch (error) {
    reply.code(400);
    return { error: error.message };
  }
});

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TypeScript Configuration

For optimal TypeScript support, ensure your tsconfig.json includes:
tsconfig.json
{
  "compilerOptions": {
    "target": "ES2020",
    "module": "ESNext",
    "moduleResolution": "node",
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "resolveJsonModule": true
  }
}

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Verification

Verify your installation by running a simple test: 
import { PaymentClient } from '@fundkit/core';

console.log('FundKit installed successfully!');
console.log('PaymentClient available:', !!PaymentClient);

// Test basic instantiation
try {
  const client = new PaymentClient({
    apiKey: 'test_key',
    providers: [],
    environment: 'sandbox',
  });
  console.log('PaymentClient instantiated successfully');
} catch (error) {
  console.error('Installation issue:', error.message);
}
Run the test: 
# For TypeScript
npx tsx test.ts

# For JavaScript
node test.js

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Troubleshooting

If you see module resolution errors: 1. Ensure you’re using Node.js 16+ 2. Check that all packages are installed: npm ls @fundkit/core 3. Clear your node_modules and reinstall: rm -rf node_modules package-lock.json && npm install 4. Verify your package.json includes the packages
For TypeScript issues: 1. Update to TypeScript 4.5+: npm install -D typescript@latest 2. Enable esModuleInterop and allowSyntheticDefaultImports in tsconfig.json 3. Use import type for type-only imports from @fundkit/types
For specific runtime environments: Cloudflare Workers: Use import syntax, not require() Vercel Edge: Ensure you’re not using Node.js-specific APIs Browser: Some provider packages use Node.js APIs and won’t work in browsers

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Next Steps

Quick Start

Build your first payment integration

Core Concepts

Learn about PaymentClient and providers

Provider Setup

Configure your chosen payment providers

API Reference

Explore the complete API documentation