Demo Apps & Examples - KillB Documentation

Overview

Explore our collection of demo applications and code examples to accelerate your integration with KillB API.

Sample Applications

On-Ramp Demo

Complete on-ramp flow from fiat to crypto

Off-Ramp Demo

Convert crypto back to local fiat currency

Savings Dashboard

Custodial savings account interface

Webhook Listener

Handle real-time event notifications

On-Ramp Demo

A complete implementation of the on-ramp flow (COP/MXN → USDC).

Features

User creation and KYC
Real-time quotation display
PSE/SPEI payment integration
Transaction status tracking
Webhook handling

Code Example

import { useState } from 'react';

function OnRampWidget() {
  const [quote, setQuote] = useState(null);
  const [amount, setAmount] = useState('');

  const getQuote = async () => {
    const response = await fetch('/api/v2/quotations', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${accessToken}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        fromCurrency: 'COP',
        toCurrency: 'USDC',
        amount: parseFloat(amount),
        amountIsToCurrency: false,
        cashInMethod: 'PSE',
        cashOutMethod: 'POLYGON'
      })
    });
    
    const data = await response.json();
    setQuote(data);
  };

  const createRamp = async () => {
    const response = await fetch('/api/v2/ramps', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${accessToken}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        quotationId: quote.id,
        userId: currentUser.id,
        accountId: walletAccount.id
      })
    });
    
    const ramp = await response.json();
    // Redirect to PSE payment URL
    window.location.href = ramp.paymentInfo[0].url;
  };

  return (
    <div>
      <input
        type="number"
        value={amount}
        onChange={(e) => setAmount(e.target.value)}
        placeholder="Amount in COP"
      />
      <button onClick={getQuote}>Get Quote</button>
      
      {quote && (
        <div>
          <p>You will receive: {quote.toAmount} USDC</p>
          <p>Rate: {quote.rate}</p>
          <button onClick={createRamp}>Continue to Payment</button>
        </div>
      )}
    </div>
  );
}

View Full Demo

See the complete on-ramp demo application on GitHub

Off-Ramp Demo

Convert cryptocurrency back to local fiat currency.

Features

Wallet balance check
Quote calculation
Bank account validation
Transaction monitoring
Receipt generation

Code Example

export default function OffRampPage() {
  const createOffRamp = async (formData) => {
    // Step 1: Get quote
    const quoteRes = await fetch('/api/v2/quotations', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${token}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        fromCurrency: 'USDC',
        toCurrency: 'COP',
        amount: formData.amount,
        amountIsToCurrency: false,
        cashInMethod: 'POLYGON',
        cashOutMethod: 'PSE'
      })
    });
    const quote = await quoteRes.json();

    // Step 2: Create ramp
    const rampRes = await fetch('/api/v2/ramps', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${token}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        quotationId: quote.id,
        userId: formData.userId,
        accountId: formData.bankAccountId
      })
    });
    const ramp = await rampRes.json();

    // Step 3: Show payment instructions
    return ramp;
  };

  return (
    <form onSubmit={(e) => {
      e.preventDefault();
      createOffRamp(formData);
    }}>
      {/* Form fields */}
    </form>
  );
}

Savings Demo

Implement a custodial savings account interface.

Code Example

// Create savings account
const createSavingsAccount = async (userId) => {
  const response = await fetch('/api/v2/savings', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${token}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      userId: userId,
      acceptedTermsAndConditions: true
    })
  });
  
  return await response.json();
};

// Get balance
const getBalance = async (savingsAccountId) => {
  const response = await fetch(
    `/api/v2/savings/${savingsAccountId}/balance`,
    {
      headers: {
        'Authorization': `Bearer ${token}`
      }
    }
  );
  
  return await response.json();
};

// Get deposit instructions
const getDepositInstructions = async (savingsAccountId, type) => {
  const response = await fetch(
    `/api/v2/savings/${savingsAccountId}/deposit-instructions/${type}`,
    {
      headers: {
        'Authorization': `Bearer ${token}`
      }
    }
  );
  
  return await response.json();
};

Webhook Listener Demo

Handle real-time webhook events from KillB.

Code Example

const express = require('express');
const crypto = require('crypto');

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

app.post('/webhooks/killb', (req, res) => {
  // Verify webhook signature
  const signature = req.headers['x-signature-sha256'];
  const payload = JSON.stringify(req.body);
  
  const expectedSignature = crypto
    .createHmac('sha256', process.env.WEBHOOK_SECRET)
    .update(payload)
    .digest('hex');
  
  if (signature !== expectedSignature) {
    return res.status(401).json({ error: 'Invalid signature' });
  }
  
  // Process webhook event
  const { event, data } = req.body;
  
  switch(event) {
    case 'ramp.completed':
      handleRampCompleted(data);
      break;
    case 'ramp.failed':
      handleRampFailed(data);
      break;
    case 'user.kyc_updated':
      handleKYCUpdate(data);
      break;
  }
  
  res.status(200).json({ received: true });
});

app.listen(3000);

Learn More

Read the complete webhook security guide

Code Snippets

User Management

const createUser = async (userData) => {
  const response = await fetch('/api/v2/users', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${token}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      type: 'PERSON',
      externalId: userData.externalId,
      data: {
        firstName: userData.firstName,
        lastName: userData.lastName,
        email: userData.email,
        phone: userData.phone,
        dateOfBirth: userData.dateOfBirth,
        address: userData.address,
        document: userData.document
      }
    })
  });
  
  return await response.json();
};

Account Creation

const createWalletAccount = async (userId, walletAddress) => {
  const response = await fetch('/api/v2/accounts', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${token}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      type: 'WALLET',
      userId: userId,
      externalId: `wallet-${userId}`,
      data: {
        firstName: 'John',
        lastName: 'Doe',
        email: '[email protected]',
        phone: '+573001234567',
        currency: 'USDC',
        network: 'POLYGON',
        address: walletAddress,
        countryCode: 'CO',
        document: {
          type: 'PASSPORT',
          number: 'AB123456',
          issuedCountryCode: 'CO'
        }
      }
    })
  });
  
  return await response.json();
};

Ramp Creation

const executeRamp = async (userId, accountId, amount, direction) => {
  try {
    // 1. Create quotation
    const quote = await fetch('/api/v2/quotations', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${token}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        fromCurrency: direction === 'ON' ? 'COP' : 'USDC',
        toCurrency: direction === 'ON' ? 'USDC' : 'COP',
        amount: amount,
        amountIsToCurrency: false,
        cashInMethod: direction === 'ON' ? 'PSE' : 'POLYGON',
        cashOutMethod: direction === 'ON' ? 'POLYGON' : 'PSE'
      })
    }).then(r => r.json());

    console.log('Quote:', quote);

    // 2. Create ramp
    const ramp = await fetch('/api/v2/ramps', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${token}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        quotationId: quote.id,
        userId: userId,
        accountId: accountId
      })
    }).then(r => r.json());

    console.log('Ramp:', ramp);
    
    return ramp;
  } catch (error) {
    console.error('Ramp creation failed:', error);
    throw error;
  }
};

Testing in Sandbox

Use these helper functions to test your integration:

Simulate Cash-In

curl --request POST \
  --url https://teste-94u93qnn.uc.gateway.dev/api/v2/faker/cash-in \
  --header 'Authorization: Bearer YOUR_ACCESS_TOKEN' \
  --header 'Content-Type: application/json' \
  --data '{
    "rampId": "ramp-id-here"
  }'

Simulate Cash-Out Completion

curl --request POST \
  --url https://teste-94u93qnn.uc.gateway.dev/api/v2/faker/cash-out \
  --header 'Authorization: Bearer YOUR_ACCESS_TOKEN' \
  --header 'Content-Type: application/json' \
  --data '{
    "rampId": "ramp-id-here"
  }'

Faker endpoints only work in sandbox environment and are used for testing purposes.

Integration Checklist

Set Up Authentication

Implement login and token refresh logic

Create User Management

Build user creation and KYC submission flows

Implement Account Creation

Add bank account and wallet management

Build Quotation UI

Show real-time prices to users

Handle Ramp Flow

Create and monitor ramp transactions

Set Up Webhooks

Receive real-time status updates

Add Error Handling

Implement proper error handling and retry logic

Test Thoroughly

Use sandbox environment for end-to-end testing

Additional Resources

API Reference

Complete API documentation

Webhooks Guide

Set up real-time notifications

Error Handling

Best practices for error management

Best Practices

Tips for production-ready integration

Have a demo app to share? Contact us at [email protected] to have it featured!

Get Started

Core Concepts

Users & KYC

Accounts

Pre-Funded Accounts

On/Off Ramps

Savings & Custodial

Webhooks

Resources

​Overview

​Sample Applications

On-Ramp Demo

Off-Ramp Demo

Savings Dashboard

Webhook Listener

​On-Ramp Demo

​Features

​Code Example

View Full Demo

​Off-Ramp Demo

​Features

​Code Example

​Savings Demo

​Code Example

​Webhook Listener Demo

​Code Example

Learn More

​Code Snippets

​User Management

​Account Creation

​Ramp Creation

​Testing in Sandbox

​Simulate Cash-In

​Simulate Cash-Out Completion

​Integration Checklist

​Additional Resources

API Reference

Webhooks Guide

Error Handling

Best Practices

Overview

Sample Applications

On-Ramp Demo

Features

Code Example

Off-Ramp Demo

Features

Code Example

Savings Demo

Code Example

Webhook Listener Demo

Code Example

Code Snippets

User Management

Account Creation

Ramp Creation

Testing in Sandbox

Simulate Cash-In

Simulate Cash-Out Completion

Integration Checklist

Additional Resources