Yes, you can absolutely set up Meta’s Conversion API (CAPI) without using Google Tag Manager.
There are several alternative methods depending on your platform and technical resources. If you're using platforms like Shopify, WooCommerce, or BigCommerce, Meta offers direct partner integrations that make CAPI setup simple with just a few clicks—no code needed.
For custom websites, you can implement CAPI manually via server-side integration by sending events directly to Meta’s API, though this does require some backend development.
Another easy option is to use third-party tools like Stape.io, LeadsBridge, or Segment, which offer user-friendly dashboards and prebuilt templates for CAPI setup. You can also use Meta’s Events Manager to walk through partner-based integration flows if you're on a supported CMS.
Overall, there are plenty of reliable CAPI setup routes outside of GTM, so you can choose the one that best matches your tech stack and team capacity.