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The Importance of Software Design Documentation in Development Projects/



Michael is a software engineer and startup growth expert with 10+ years of software engineering and machine learning experience.

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The Importance of Software Design Documentation in Development Projects
The Importance of Software Design Documentation in Development Projects

If you’re an experienced developer, you’ve probably progressed from being a humble tester to a senior developer, and if you’re a freelancer, you’ve made another leap, perhaps the biggest of them all, when you started working with clients directly. Some clients aren’t in the software business; they’re in an entirely different industry that needs a piece of software, and they don’t have a clear and precise vision of what they want from you. This is a far greater challenge than it appears, and here’s what you can do to improve client communication and project documentation.

Congratulations, you have become a skilled and capable independent developer. You have come a long way from your early days as a tester and have progressed to working as a team developer, a senior developer, and now, to the most significant leap of working directly with clients.

However, unlike the linear progression of your past transitions, this last one has been exponential. You are now responsible for all aspects of the project that were once divided between expert-testing and program management, among others. Furthermore, you are now working with clients who are not software experts and may have difficulty expressing their needs clearly. This presents a significant challenge that requires careful handling.

To overcome this challenge, it is important to improve communication with clients and enhance project documentation. This will ensure better collaboration and a clear understanding of the project requirements.

The Importance of Software Design Documents

Before diving into coding, clear and agreed-upon design goals are essential for a successful project. A specification document must be established, even if the client hasn’t provided one. If a client refuses to create a design document, it’s best to walk away from the project as trouble is ahead.

The software design document need not be lengthy but should include the user interface and wireframes (if there’s a UI component). It’s also important to set completion milestones. Without this document, disagreements will arise, leading to arguments, disputes, and revisions that will ultimately waste time and money.

However, with a software design document, disagreements can be addressed by referring to the agreed-upon specification. Amendments and clarifications can be made to the document, and the client will apologize for the imprecision.

To achieve a satisfactory outcome, a friendly working relationship, and pride in a job well-done, it’s essential to have clarity on what the job entails. If a client is reluctant to create a design document, explain that it’s necessary to avoid any misunderstandings or revisions later on. If a client still refuses, it’s better to walk away than enter an unworkable relationship.

Importance of the Software Design Specification and Its Content

Importance of the Software Design Specification and Its Content

Before starting a new software project, it’s crucial to establish clear design goals and create a specification document. This document should outline the desired application, criteria for completion, and project milestones. It serves as a requirements and function document and not an implementation specification, leaving the choice of implementation up to the developer.

User Interface Considerations

Most projects are applications, and the user interface is the most complex component of a design document. It often leads to misunderstandings between clients and developers, especially when the client provides graphic illustrations that don’t convey all the necessary details. These illustrations may lack information on animations, control states, or button actions, causing confusion during the development process.

Importance of Functionality in Software Design Specification

When creating a software design specification, it’s important to clearly define the application’s functionality, possible failure conditions, one-time operations, and limitations on user entries. Being detailed and thorough is crucial to avoid errors and misunderstandings that could lead to rewriting code.

Milestones are also a critical component of a software design specification, as they provide a clear metric toward completion. Milestones should be agreed upon with the client and should be approximately equal in duration. They may include billing thresholds and can be in terms of functionality and/or components, even separate applications for larger projects.

It’s important to note that the user interface is often the most problematic component of a design document template. If a client provides illustrations of the user interface, it’s crucial to discuss animations, control states, and button actions to avoid misunderstandings.

By creating a clear and detailed software design specification that defines functionality and milestones, you can avoid errors and misunderstandings that could lead to time-consuming code rewrites.

Example Software Design Specification

The following is an example structure for a software design document. Keep in mind that this template can be adjusted as needed. For an additional example, take a look at Joel Spolsky’s sample specification, which is based on this write-up. Although he takes a slightly different approach to the document, his sentiment is similar.

  • Objectives: Provide a brief paragraph that describes the project and its target audience.
  • Functionality: Description What does the application do? What are the high-level descriptions of the primary user scenarios that the user will encounter?

For instance, your functional description could resemble:

First Run Creating a New ____ (game, search, etc.) Operations Background and Foreground Behaviour

  • User Interface: Include wireframes for each page, with detailed descriptions of:

Every control, including its enabled/disabled/highlighted states and operations. Supported transitions and orientations between them. Functionality that is represented. Error handling. Dimensions and constraints.


As described above, deadlines for completion and expected deliverables. For example, the milestones section in your design document template might look like:

  1. Facade Application showing screen and with temporary transitions and example images/text
  2. Communication Protocol: application connects to network/server
  3. Functional Milestone 1: …
  4. Alpha Application (with full functionality)
  5. Stability
  6. Release

Ensuring Relevance of Software Documentation

Ensuring Relevance of Software Documentation

The software design process doesn’t end with an agreed-upon specification document. Often, there are details that you and the client may have overlooked or encountered new ideas, design changes, and unexpected design flaws during the development process. Thus, it’s important to capture all these changes in your document.

Regular communication with the client is also essential. It’s recommended to touch base several times a week, report on progress, ask for clarifications, and ensure you both have the same vision for the project. To test your communication, try to ensure that you and your client give the same answers to the following questions:

  • What was the developer working on?
  • What is the developer working on now?
  • What will the developer work on next?