Can I Connect Custom HTTP APIs on Clay's Free or Starter Tier?

Hey good people, I'm currently using Clay's free tier and want to experiment with connecting to additional HTTP APIs beyond the built-in integration. Looking at the pricing page, I see 'Integrate with any HTTP API' is only available starting with the Explorer tier ($349/month). Could you confirm if this means I need to upgrade to Explorer to connect custom APIs, or is there any way to do this within the Starter tier ($149/month)/Free tier?