Official Shopify guides and articles
Good overview covering the overall process - start here.
Good beginners level article demystifying the app dev process
Some excellent in-depth guides
A selection of great articles from his newsletter
Eyal Toledano’s documentation around his journey growing his Shopify App portfolio
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Slightly outdated (2017) guide about buying/selling Shopify Apps, still useful though
Four useful blog articles
Useful blog posts from Baremetrics
Great in-depth blog posts around revamping an acquired Shopify app
Useful App Store insights from the masterful Daniel Sim
Tutorials for Shopify app development | Nozzlegear Software
Thanks to recent changes to the HTTP Cookie SameSite spec, Asp.Net cookies and AntiForgery tokens have stopped working in Shopify embedded apps and iframes. Shopify has deprecated the first version of their API, necessitating a new major release of ShopifySharp.
Tutorials and essays for building Shopify applications with C#, ASP.NET, F#, .NET Core and more.
Other miscellaneous articles and blog posts