Alternative to Sparkloop Magic for One-Click Sign Up

Has anyone:

  1. Come across Sparkloops new tool, Magic, which enables one-click sign up embedded within newsletter (Magic — One-click signup links by SparkLoop). And if so,

  2. Do you know of an alternative? It doesn’t look like it’s compatible with Ghost, and we are running a cross-promotion with another newsletter who wants to embed it with their campaign.

Thanks!