If you can’t add any code or HTML to the target URL, you have a few solid options for setting up a conversion event in Facebook:
1. Use Facebook’s Built-in Events from Lead Forms or Instant Experiences
If you’re using Facebook Lead Ads, Instant Forms, or Instant Experiences, Facebook tracks conversions automatically — no extra code needed.
2. Use URL-Based Conversion Tracking (Custom Conversions)
If the target URL redirects to a thank-you page, you can:
Set up a Custom Conversion in Events Manager
Choose your Pixel
Define the conversion by URL contains: thank-you, confirmation, etc.
No code is needed as long as the Facebook Pixel is already installed somewhere on the domain.
3. Use Meta’s Conversions API (if server-side is an option)
If you or a partner can send conversion events from the server, use Conversions API to log conversions — even without client-side pixel code.
If you can’t add code, use Lead Forms, Custom Conversions via URL, or explore server-side options like Conversions API. Let me know your setup — I can suggest the best route!