Here's a list of helpful resources we use ourselves and think you'll find useful.
Email Marketing Customer.io for advanced email marketing and automation, Klaviyo for e-commerce, or EmailOctopus if you're looking for something easy to use and light on the wallet.
Online Courses Thinkific for your standard online course, Clarityflow if you want to include coaching, and ClassroomIO if you want open-source.
Websites For a website that is professionally designed to generate leads, SEO optimised for better rankings, custom coded for lighting fast pages, and includes unlimited website updates—check out What Web Design.
Databases For serious backend work, check out Supabase, or for a no-code solution we recommend Airtable, or for an open-source solution look at Baserow.
Design Figma is becoming the defacto software for web related design and you can start with a free plan. Need something that can open your old photoshop files, then Photopea is a free online, Photoshop-like software.