How to design and engineer a SaaS app is often discussed in terms of visual design (e.g. using Bootstrap and images in web pages) or choosing a tech stack (e.g Ruby on Rails vs. node, NoSQL vs. SQL). These are not an end on itself, these are means to get your SaaS working.
A complementary view is to look at the UI flow and UX design in an early stage and try to build a SaaS app with user flow in mind. UI flow is easy to sketch in text only, and while doing this you’ll notice what kind of data and state your app must keep.
Once you have a sketch of your UI flow, this sketch allows for focused discussion between backend engineering and visual/interaction design.
The most useful resources are:
- My favorite: https://signalvnoise.com/posts/1926-a-shorthand-for-designing-ui-flows . A quick and easy method to define UI flows in text format. Engineers and designers can easily understand this and collaborate on the main SaaS app functions.
- http://conversionxl.com/how-to-design-user-flow/ An overview of how to design user flow, mainly from a conversion perspective.
- How to design UI flow without drawing: http://innovation.avg.com/2014/12/23/jumpstarting-your-app-conception-without-sketching-ui/ This method keeps track of how much information your users have to provide to accomplish a task.
- A more UI content focused approach is described in: https://www.startuprocket.com/articles/why-writing-a-user-interface-spec-is-critical-for-startup-teams . This method makes it easy to communicate with a designer in an early stage, and to roughly generate a visual prototype.
- UX flowchart design as a graphical prototype: https://www.startuprocket.com/articles/the-7-benefits-of-building-a-ux-flow-chart-before-writing-a-line-of-code . This type of UX flowchart is a form of a site map, showing which pages are reachable from which and the main user interactions. You can use this to get a general overview, but don’t put to much detail in this kind of flowchart, as it gets to crowded.
[UPDATE Feb 12th, 2017]
Once you have a prototype of your SaaS (or just your website) running, ask your visitors and customers for feedback. The key is to ask in such a way that it is low effort to give the feedback. One of the best methods is to use NPS (Net Promoter Score), because it is a standard and well-known method. FanExam is a service which can collect NPS for you, both on a public website and on a SaaS. It is very simple to set up and use.