SharePoint Hosted Add-In or Plain Old JavaScript / HTML5 / CSS?

When Microsoft released the SharePoint App-model (meanwhile renamed to Add-In model), it almost instantaneously became the preferred and dominant development approach for SharePoint customization. Now several years later, and the hype is gone, the question arises whether the Add-In model is the right answer for all SharePoint customization scenarios.

I dare to say no. And feel myself strengthened in that opinion by Microsoft’s latest and greatest SharePoint development approach: the SharePoint Framework. Yes, the Add-In model brings a lot of value, but at the expense of additional development, maintenance and runtime (performance) costs. In case you can bring the same functional value via a strict JavaScript + HTML5 + CSS setup, you can avoid these additional costs. Simple deploy the functionality via resource files, upload to a document library, and include them in the runtime SharePoint page context via a ScriptEditor. Much simpler to develop and deploy than a SharePoint hosted Add-In. And not hindered by iFrame boundaries.

Does this mean I see no value at all for the SharePoint-hosted Add-In model? No, there are definitely scenarios. A clear one is that of a software vendor: with an Add-In the vendor has a self-contained package that buyers can install in their SharePoint site. Another example is for a piece of functionality that is reused throughout the site structure, and that needs per usage its own storage in SharePoint. The Add-In model can provision this per Add-In installation in either the hostweb or the appweb.