Slemma offers Free Trial, but Authorize.Net does not.
Authorize.Net is designed for Large Enterprises, Medium Business and Small Business.
Slemma is designed for Medium Business and Small Business.
Pricing for Authorize.Net Starts at $25/Month whereas for Slemma Starts at $89/Month when Billed Yearly.
Some top alternatives to Authorize.Net includes Stripe Payments, QuickBooks Payments, PayorCRM, UniPay Gateway, NETELLER, NextPay Payment Gateway, Airpay, Better Payment, aPay Payment Gateway Systems and PayNet.
Some top alternatives to Slemma includes Alteryx, iDashboards, DataHero, Databox, DashThis, Klipfolio Dashboard, myDATA3, Easy Insight, AppInsights and Analytics Canvas.