17 May 2019

Differences between functional and technical specifications

When engaging in any sort of digital product build or transformation project, it’s important to put time into laying down your requirements. Let’s discuss two key documents involved in this process: functional specifications and technical specifications.

Although the two are used in conjunction to develop digital products, it’s important to articulate each set of requirements well, and to not confuse them. 

In this article, we look at how the two types of specifications differ, how they work together, and why they’re so essential to the digital process.


What is a functional specification?

Functional specifications describe, in plain English, the functionality your users should experience. This doesn’t include design elements or technical information, such as what software will be used, just the basic functional requirements. It needs to be looked at from the user’s perspective, with an understanding of potential features, screens, menus and dialogue. 

For example, a GP practice may be looking to build a new online booking system. The functional specifications for this project will include considerations such as:

  • What fields need to be included on the form?
  • What happens when a user enters the wrong information? 
  • What is displayed if an error occurs?
  • What does the user see when they click the submit button? Does this lead to a ‘success’ message or pop-up? 
  • What page will the user be directed to next? 

Your functional specification won’t include details like, ‘we’ll use X software’, or ‘we’ll put our logo here’. The idea is to keep it simple, straightforward and user-centric. Once you have this information, software can be developed to meet your functional specifications.

Outlining functional considerations effectively will ensure that your developer builds a product that actually works and does what you want it to do. 

Once you’ve outlined your functional requirements, you need to look at the technical aspects of the project. 


What is a technical specification?

Your technical specifications will detail how the product will be built. This is where we talk about technology, software and capabilities. It will include considerations like what technology will be used or how data will be collected and stored. Because of the technical nature of this document, it needs to be written by a technical person – someone who understands the language and can communicate the requirements to a developer.

If we again look at the example of the GP practice implementing an online booking system, the technical specs will outline things like:

  • How can we implement calls to the server?
  • How will the data collected from the booking form be saved to a database?
  • Will the patient form have server-side validation when the form is submitted, or client-side validation?

Technical specs can be relatively straightforward, as in the example above, or they can be incredibly complex. We’ve worked on big projects where these have included hundreds of lines of technical requirements.

While it may be tempting to add technical details to your functional specifications, it’s important to separate the two. They will, however, be used in conjunction.


How do they work together?

While technical and functional specifications work closely together, they need to be separate documents. Functional specs that include lots of technical information can confuse the process, forcing people to begin talking about software capabilities before the user experience is properly mapped out from a functionality perspective.

In saying that, the two do work very closely together. For example, when a developer is building your online booking form, they can go back to the functional specification to understand the ‘why’ and what functionality you want the user to experience.

Both functional and technical specifications should be developed by people who understand the unique challenges your organisation is facing, as well as the needs of your users. The technical spec also needs to be written specifically by a technical person who understands the language. For this reason, you should consider having an expert help you get this process right.


Why are they important?

If you don’t take the time to outline your specifications, you may not obtain the end result you’re hoping for. This process can be performed with the help of a digital agency like Tadashi.

We see many organisations approach agencies with their idea of a digital product solution. For example, ‘we’d like a website with five pages and it must be blue’. You should approach us before this stage, as we’ll break down the digital process for you and develop the specifications you need to meet both your organisation’s and users’ needs.

This is a particular challenge in the tender process, as clients often document what they think they need, and agencies can only respond to that. It’s much more useful for us to work with you to define what you actually need to build, and the steps required before development.


Having helped many organisations execute digital projects, we’re well-versed in functional and technical specifications processes. We can help your organisation clearly articulate what your needs are, ensuring a smooth digital product build. Get in touch with us to kickstart a conversation about your next project.

If you liked this article you can share it here

Scroll Up Button