NectoProxy

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Debugging Mobile Apps ​

Difficulty: Intermediate | Time: 15 minutes

This tutorial shows you how to capture and inspect HTTP/HTTPS traffic from iOS and Android devices using NectoProxy. By routing your phone's traffic through NectoProxy, you can see every API call, debug network issues, and even mock or modify responses on the fly.

Prerequisites ​

  • NectoProxy installed on your computer
  • Your computer and mobile device connected to the same Wi-Fi network
  • Physical access to the mobile device you want to debug

Step 1: Start NectoProxy ​

NectoProxy binds to all network interfaces (0.0.0.0) by default, so your phone can connect without any special flags:

bash
nectoproxy start

NectoProxy will display your LAN IP address at startup (e.g., http://192.168.1.42:8888). Note this address -- you will need it to configure your phone.

Security Note

Since NectoProxy listens on all interfaces by default, it is accessible to your entire local network. Only use it on trusted networks (e.g., your home or office Wi-Fi). If you want to restrict to localhost only, use --host 127.0.0.1.

Step 2: Find Your Computer's IP Address ​

You need your computer's local IP address so your phone knows where to send traffic. NectoProxy shows available addresses in the Settings panel.

Via the Web UI ​

  1. Open the NectoProxy Web UI at http://localhost:8889.
  2. Click the gear icon to open Settings.
  3. Scroll down to the Mobile Configuration section.
  4. Your computer's IP addresses and network interfaces are listed there (e.g., 192.168.1.42).

Via the Terminal ​

bash
# macOS
ifconfig | grep "inet " | grep -v 127.0.0.1

# Linux
hostname -I

# Windows
ipconfig | findstr /i "IPv4"

Look for an address on your local network, typically starting with 192.168., 10., or 172.16-31..

TIP

If you have multiple network interfaces (e.g., Ethernet and Wi-Fi), use the IP address of the interface that is on the same network as your phone.

Step 3: Configure Your Phone's Wi-Fi Proxy ​

iOS (iPhone / iPad) ​

  1. Open Settings on your iPhone.
  2. Tap Wi-Fi.
  3. Tap the info button (i) next to your connected Wi-Fi network.
  4. Scroll down to HTTP Proxy and tap Configure Proxy.
  5. Select Manual.
  6. Enter:
    • Server: Your computer's IP address (e.g., 192.168.1.42)
    • Port: 8888 (or your custom proxy port)
    • Authentication: Leave off
  7. Tap Save.

Android ​

  1. Open Settings on your Android device.
  2. Tap Network & Internet (or Wi-Fi, depending on your device).
  3. Long-press on your connected Wi-Fi network, then tap Modify network (or tap the gear icon).
  4. Tap Advanced options (or expand advanced settings).
  5. Change Proxy from None to Manual.
  6. Enter:
    • Proxy hostname: Your computer's IP address (e.g., 192.168.1.42)
    • Proxy port: 8888
    • Bypass proxy for: Leave empty
  7. Tap Save.

WARNING

The exact steps vary slightly between Android manufacturers (Samsung, Pixel, OnePlus, etc.). The general flow is the same: Wi-Fi settings, select your network, set proxy to Manual, and enter the IP and port.

Step 4: Install the CA Certificate ​

Without the CA certificate, your phone will show security errors for all HTTPS traffic. NectoProxy provides two convenient ways to install the certificate.

  1. In the NectoProxy Web UI, open Settings (gear icon).
  2. Scroll down to Mobile Configuration.
  3. A QR Code is displayed that links to the certificate download URL.
  4. Open the Camera app on your phone and point it at the QR code.
  5. Tap the notification/link that appears to open it in the browser.
  6. Follow the prompts to download and install the certificate.

Method B: Manual URL ​

  1. On your phone's browser (with the proxy already configured), navigate to:

    http://<your-computer-ip>:8889/api/certificates/download

    For example: http://192.168.1.42:8889/api/certificates/download

  2. The certificate file will download.

Installing the Downloaded Certificate ​

iOS ​

  1. After downloading, a prompt appears asking to install the profile. Tap Allow.
  2. Go to Settings > General > VPN & Device Management (or Profile & Device Management).
  3. Tap the NectoProxy CA profile and tap Install.
  4. Enter your passcode if prompted, then tap Install again.
  5. Important: Go to Settings > General > About > Certificate Trust Settings.
  6. Toggle Enable Full Trust for the NectoProxy CA certificate.

DANGER

On iOS, you must complete both steps: installing the profile AND enabling full trust. The certificate will not work for HTTPS interception until full trust is enabled.

Android ​

  1. After downloading, you may see a prompt to install the certificate. If so, follow it.
  2. If no prompt appears, go to Settings > Security (or Security & Privacy) > Encryption & Credentials > Install a certificate > CA certificate.
  3. Select the downloaded certificate file.
  4. Confirm the installation.

WARNING

On Android 7.0 (Nougat) and later, user-installed CA certificates are not trusted by apps by default. Apps must explicitly opt in via their network security configuration. System apps and browsers will work, but some apps may still reject the certificate. For those apps, add the domain to SSL passthrough in NectoProxy settings.

Step 5: Browse on Your Phone ​

With the proxy configured and the CA certificate installed, open any app or browser on your phone. You should see traffic appearing in the NectoProxy Web UI in real time.

Things to verify:

  • HTTP requests appear immediately in the traffic list.
  • HTTPS requests appear with full URL, headers, and bodies (not just the CONNECT tunnel).
  • The phone's browser does not show certificate errors for standard websites.

TIP

If traffic is not appearing, double-check:

  1. Your phone is on the same Wi-Fi network as your computer.
  2. The proxy settings are saved (try opening a website in the phone's browser).
  3. NectoProxy is not restricted to localhost (avoid using --host 127.0.0.1 when debugging mobile).
  4. Your computer's firewall is not blocking port 8888.

Step 6: Using the QR Code Feature ​

The QR code in the Settings panel encodes the certificate download URL. This is the fastest way to get the certificate onto your phone:

  1. Open NectoProxy Settings (gear icon).
  2. If you have multiple network interfaces, select the correct one from the dropdown above the QR code.
  3. Point your phone's camera at the QR code.
  4. The URL resolves to http://<ip>:<uiPort>/api/certificates/download.

The QR code updates automatically when you change the selected IP address or UI port.

Cleaning Up ​

When you are done debugging, remember to:

  1. Remove the proxy settings from your phone's Wi-Fi configuration (set proxy back to None).
  2. Optionally remove the CA certificate from your phone if you no longer need it.

Removing the CA Certificate ​

iOS: Settings > General > VPN & Device Management > NectoProxy CA > Remove Profile

Android: Settings > Security > Encryption & Credentials > Trusted Credentials > User tab > NectoProxy CA > Remove

WARNING

Leaving the proxy settings configured on your phone after stopping NectoProxy will cause your phone to lose internet connectivity, because it will try to route all traffic through a proxy that no longer exists.

Tips for Mobile Debugging ​

  • Use the filter bar in NectoProxy to focus on traffic from your app's API domain, reducing noise from background system requests.
  • Create mock rules for APIs your mobile app calls to test edge cases without modifying server code.
  • Use SSL Passthrough for domains you do not need to inspect (e.g., analytics, crash reporting). This avoids certificate pinning issues with SDKs that do not trust user-installed CAs.
  • Check the WebSocket tab if your mobile app uses real-time communications. WebSocket frames are captured alongside regular HTTP traffic.