What is a functional specification?
Functional specification is a document tailored to present a general review of requirements and features of the product to be created. A well-developed functional specification document is crucial for development as it allows for determining a complete volume of work and ensuring a deep comprehension of the product.
A functional spec is a blueprint for software developers enabling them to understand what a stakeholder expects from the software solution in terms of its look, capabilities, and interactions with end users. Functional software specification also aims to ensure a synchronized work of the development, design, and QA teams guided by a project manager.
What should a functional specification document contain?
As a rule, a spec document contains the following elements:
Stakeholders
The opening part of the specifications document should include the names and responsibilities of everyone engaged in the project.
Product overview
It contains information about the target audience of the product, successful use cases, and specific problems that can be tackled with its help.
Project scope
This section of the documentation represents a set of functional and non-functional requirements, order for putting them into practice, and feature specifications previously agreed on with a client. Project deadlines and budget may be also specified here.
Potential project risks
The risks part outlines possible problems that can arise during the software development cycle. The issues may concern technicalities, costs, timelines, or other aspects influencing the product’s functional design.
User journeys
The key players, procedures, data flows, interactions, and exceptional circumstances are set forth in this part of functional spec.
Why create a functional specification documentation?
A software and mobile app specification document ensures a clear understanding of the final product for the clients assisting them in several aspects:
- communicates the idea in a plain way,
- avoids any potential confusion and adds to the project transparency,
- minimizes a number of recurrences,
- quickens product development,
- evaluates the cost of development, and
- mitigates the risk of ending up with low-quality and inefficient products.
How to write a functional specification?
Traditionally, a project manager collaborates with software developers, UI/UX designers, and stakeholders to generate a comprehensive vision of the intended product and its characteristics.
Crafting an effective functional specification document involves taking the following steps:
Introduction to functional specification
First, the aim of the document and a person in charge of it are stated. Second, general information concerning the product, its purpose, and target customers are outlined. Third, specific terms that will be used in a spec document are introduced and explained.
User stories
Software products can have one, two, or even more roles. So, various kinds of potential users are described. User stories are meant to reveal each role specifying how a specific group of customers can benefit from it. Such stories help stakeholders and developers grasp the product functionality from a user’s perspective.
Key screens
This section of the document should characterize every screen of the app. The details to be mentioned include mandatory fields in the form, settings for the switchers by default, and outcomes of clicking a specific link or button.
High-quality design
To come up with a compelling design, it is obligatory to describe the tech stack, prepare a database scheme, select the data structures and storage, decide on the languages, and specify the third party integrations if required.
Functional requirements examples
Functional requirements are meant to give a detailed account of how a system should behave under specific circumstances.
Consider the examples given below to get an idea of such requirements:
- A system sends a confirmation request if a user enters his personal data.
- A ride app enables a driver to mark in the application when the trip is over.
- A search feature allows users to look for a specific invoice if they need to pay an issued invoice.
- A payment system ensures transaction corrections and cancellations.
These examples demonstrate particular functionalities a software product is expected to perform.