Overcoming Geolocation Barriers: Building Open Source APIs for Testing Geo-Blocked Features

In the realm of software development and testing, geo-restrictions often pose significant challenges. Many streaming services, APIs, and online features are geo-blocked, making it difficult for researchers and developers to evaluate their functionality across different regions. This blog explores how a security researcher can leverage open source tools to develop APIs that simulate different geographic locations, effectively bypassing geo-blocking restrictions during testing.

The Challenge of Geo-Blocked Features

Geo-restrictions are implemented to enforce regional licensing, security policies, or compliance measures. Testing these features across various jurisdictions requires either complex VPN configurations or access to regional user data, which can be cumbersome and inconsistent.

Solution Overview

The goal is to create a lightweight, reliable API that can:

• Mimic different geolocations based on user requests
• Intercept and modify outgoing requests to simulate geographic origin
• Integrate seamlessly with existing testing frameworks

Open source tools such as Node.js, Express, and GeoIP databases can facilitate rapid development of such an API.

Implementation Strategy

Below is a step-by-step methodology for building a location simulation API:

1. Setup a Basic API Server

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

app.use(express.json());

app.post('/simulate-location', (req, res) => {
  const { ipAddress } } = req.body;
  // Placeholder for GeoIP lookup and request forwarding
  res.send({ message: `Simulating location for IP: ${ipAddress}` });
});

app.listen(3000, () => {
  console.log('API server running on port 3000');
});

2. Integrate GeoIP Database

Use open source MaxMind GeoIP2 databases to determine geographic information from IP addresses.

const maxmind = require('maxmind');

const lookup = maxmind.openSync('./GeoLite2-City.mmdb');

app.post('/simulate-location', (req, res) => {
  const { ipAddress } } = req.body;
  const geoInfo = lookup.get(ipAddress);
  res.send({ geoInfo });
});

3. Proxy Requests with Geo-Location Headers

Use request-promise or axios to forward requests, adding headers or modifying the origin as needed.

const axios = require('axios');

app.post('/simulate-location', async (req, res) => {
  const { targetUrl, ipAddress } } = req.body;
  const geoInfo = lookup.get(ipAddress);
  const fakeHeaders = {
    'X-Forwarded-For': ipAddress,
    'X-Geo-Region': geoInfo && geoInfo.country ? geoInfo.country.iso_code : 'US'
  };
  try {
    const response = await axios.get(targetUrl, { headers: fakeHeaders });
    res.send(response.data);
  } catch (error) {
    res.status(500).send({ error: 'Failed to fetch target URL' });
  }
});

Usage and Testing

Testers can now send POST requests with the target URL and desired IP address, and the API will simulate responses as if they originated from the specified region. For example:

{
  "targetUrl": "https://example-streaming-service.com/api/feature",
  "ipAddress": "192.0.2.1"
}

This setup allows a security researcher to verify how geo-restricted features behave without deploying or relying on VPNs. It also enables automated testing scripts to simulate multiple regional scenarios efficiently.

Conclusion

By leveraging open source tools such as Node.js, MaxMind GeoIP, and proxy libraries, security researchers can create a flexible, scalable API to emulate different geolocations. This approach reduces dependency on costly VPN services, accelerates testing cycles, and enhances the robustness of geo-restricted feature verification.

Implementing such solutions ensures compliance with licensing, boosts testing coverage, and improves understanding of geo-restriction mechanisms in modern web applications.

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🛠️ QA Tip

To test this safely without using real user data, I use TempoMail USA.