Hey there, let's break down why this is happening and how to fix it:

Why This Happens #

Viber's custom URL scheme (viber://) only works if the Viber desktop app is already installed and has registered this protocol with your system. If the app isn't present, your browser/OS has no built-in rule to redirect you to the Viber download page—custom protocols don't come with automatic fallback behavior out of the box.

How to Implement the Fallback You Want #

To get the "redirect to download page when Viber isn't installed" behavior, you'll need to add a bit of frontend JavaScript to handle the link click and fallback logic. Here's how to do it step by step:

• First, replace direct viber:// links with a click handler
  Don't let users click the raw viber:// link directly. Instead, use a button or styled link that triggers a JavaScript function.

• Add the fallback logic code
  Here's a working example you can adapt:

  // Target your link/button by ID
  document.getElementById('open-viber-chat').addEventListener('click', function(e) {
    e.preventDefault();
    
    const targetNumber = '+1234567890'; // Replace with your target number (include country code!)
    const viberDeepLink = `viber://chat?number=${targetNumber}`;
    const viberDownloadPage = 'https://www.viber.com/download/';
  
    // Try to open Viber
    window.location.href = viberDeepLink;
  
    // Set a timer to check if the app opened successfully
    setTimeout(() => {
      // If we're still on the same page, the app didn't open—redirect to download
      window.location.href = viberDownloadPage;
    }, 1500); // 1.5 seconds is enough time for the system to attempt to launch Viber
  });
  

• Tweak for better user experience

  • Add a small loading message like "Opening Viber..." right after the click, so users know something's happening
  • Note that some browsers might block the custom protocol launch—you can add a fallback message like "If Viber doesn't open, click here to download it" alongside the automatic redirect

Quick Notes #

• Make sure your target number includes the full international country code (e.g., +86 for China, +1 for the US) in the deep link—otherwise Viber might not recognize it correctly
• This approach works for most custom app protocols (WhatsApp, Telegram, etc.) since they all have the same "no built-in fallback" limitation

内容的提问来源于stack exchange，提问作者deny Vice