I am interested in understanding how does one go about planning a migration of a dynamic SaaS site to a JAMstack based site.
I am aware that smashing magazine has managed this successfully (they are now really fast). However, they are a media house and do not have interactivity that one expects from a modern SaaS site. What parameters would you use to judge such migration?
JAM stack isn't just for content sites and depending on your site specifically, it may or may not be a good fit. The API layer is not necessarily just HTTP GET /something/.<p>Let's say you run a small SaaS site, let's say it's a geoip lookup service, one of the more feasible type of small SaaS you can run by yourself. The features you may need are, say, a landing page, some documentation, a sign up and login process, accepting payments, and some admin management tool. All of above can reasonably be implemented in a JAM stack site. Things like the admin console page can have a lot of the page's structure statically displayed and dynamic data filled in from API calls.<p>IMO, "migrating" a web app from a traditional web app stack (LAMP, Rails, MERN, etc.) is an architectural redesign and depending on your existing codebase, could be a full rewrite. It's a paradigm shift. You may want to evaluate the cost of that vs the benefit.
I think "JAMstack" is for content, not interactive services. If your 'service' can be reduced to<p>HTTP GET /something/<p>I think JAMstack can do it, but if it involves looking something up in a database, writing something into a database, etc. that is out-of-scope.