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Software Design Documentation Template

Software design documents explain how a specific piece of software or software feature should be developed. They're important technical documents that focus on the how of the development process. A design documentation template is all you need to write outstanding documentation to impress your clients!
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What is software design documentation?

Software design documents explain how a specific piece of software or software feature should be developed. They’re also referred to as software design specification documents or technical specification documents. Like other technical documentation, it rests in your knowledge base.

Like a product roadmap, technical spec documents are a roadmap of the entire dev process of a software. A comprehensive SDD outlines your software's architecture design, use cases, wireframes, and essential APIs. By defining specs, it ensures that the software development team and testers are aligned throughout the software development lifecycle.

Pro Tip: Software design document is different from software requirements document. The software requirements doc focuses on your product’s capabilities, while SDD focuses on processes.

Why are software design documents important?

Software design documents are important because they align all stakeholders on software design. Based on the software vision, budget, bandwidth, and timelines - software design documents outline all the tech decisions that’ll be needed to deliver the project on time. They’re a smaller part of a team’s overall technical documentation.

If you don’t have software design documents, your team will have issues in ticket measuring, sprint planning, etc. SDDs also help teams forecast likely challenges/roadblocks and thus, pre-emptively plan for the same.

That’s why, you need to have thorough SDDs. With SDDs, you’ll plan your resources better. You’ll set more accurate expectation with your team. This will ensure every other project stakeholder can move things around, if needed.

Who writes software design documentation?

Software design documents are written by product managers, the product owner, software designers, and other high-level design team members.

Essential parts of software design documents

The essential parts of a software design document include:

  • Summary
  • Functional description
  • Developer Guidelines
  • UI/UX Instructions
  • User stories
  • Milestone breakdown
  • Define the system architecture strategy
  • Testing and Maintenance Work-up
  • A 'Best Practices' Glossary

Let’s look at all of them in detail:

Summary and functional description of the software

A general summary of the software and its functionality keeps goals on track and quickly informs new stakeholders of the overall mission. This should include essential components, identifying details, and a description of what the software will do.

A detailed design document template will facilitate the creation of such a summary section.

Developer guidelines

Guidelines provide clear instructions to the development team, ensuring consistency and cohesion. These rules serve as a reference point for coding standards, naming conventions, and architecture decisions. This ensures that the codebase is consistent, maintainable, and scalable.

A well-documented software design template also mitigates risks by outlining assumptions and dependencies, thus facilitating better risk management and change control.

UI/UX instructions

UX (User Experience) and UI (User Interface) instructions are guidelines for designers and developers to help them create effective, user-friendly products. These instructions ensure that the product is intuitive, cognitively sound, and highly useful.

When creating software application design documentation, UX and UI procedures should include design elements, colors, fonts, and code snippets.

User stories

You can gather user experiences from similar existing software products to learn from others' past mistakes. Using hypothetical situations in which users employ the product to achieve a specific goal, developers can understand their decision-making to create a more intuitive product.

A detailed design document template incorporates user stories for an added level of UX improvement.

Breakdown of milestones

When there are clear milestones combined with an outline of functional goals, a detailed design document template doubles as a kind of product roadmap. Milestones such as core app services and data development provide expectations of a healthy timeline while maintaining transparency. Engineers can refer back to software documentation guidelines routinely so as not to stray too far from their foremost goals.

Define the system architecture strategy

The system architecture provides a framework for designing and integrating various subsystems, components, and services to achieve the desired functionality, performance, and scalability. These critical metrics determine the size and scale of the system.

We've provided numerous software design document examples for developers to seek inspiration.

Testing and Maintenance Work-up

Our agile design document templates leave room for testing and maintenance guidelines. It's the manager's responsibility to direct all stages of testing, including:

  1. Unit testing
  2. Integration testing
  3. System testing

A maintenance plan will outline how the system will be monitored, updated, and maintained over time. Ongoing testing should be frequent to ensure the system continues to perform as expected.

A 'Best Practices' Glossary

A system design document template contains a section dedicated to best practices and general guidelines for completion. This glossary outlines details from the brand kit to coding criteria. It might include details on product methodology, algorithms, design patterns, programming languages to be used, etc. The goal of these instructions is to help operations stay efficient and deliberate.

Benefits of software design documentation

Software design documents aren't exactly beloved by software developers and engineers (no one likes to do the work), but they can truly work wonders for your software development process. If you'd enjoy some extra help, our easy-to-use design documentation template takes a lot of the writing burden off your plate. They offer tons of benefits, including:

1. Saved Time

Let's face it, the reason people dislike software design documents is because they force them to put the work in and get organized early in the game. This is actually a great thing. When a development team gets their thoughts down on paper at the outset of a project, it helps everyone get organized and avoid doing unnecessary work. Also, more time is saved when you utilize the fast-tracking benefits of our design documentation template.

2. Increased Transparency

No one likes conflict with clients or other external stakeholders. Putting together a great development guide from a software design template helps avoid just that. A great design doc can act as a kind of informal contract between clients and programmers. You'll both agree on the most important details of your software development at the outset, fostering clear communication on both sides.

Pro Tip: If any client misunderstandings arise in the future, you'll be able to refer back to what you agreed upon in your design docs.

3. Effective Teamwork

Software design documents aren't static files anymore; they're dynamic and foster great collaboration, especially when they're developed on a collaborative platform like Slite. Since the vast majority of software is designed collaboratively, these documents provide a central document for various team members to refer back to. For example, the application design documentation provided by us here on Slite is team-centric, encouraging project managers and lead developers to involve their teams in the writing process.

4. Reveal Hidden Opportunities for Further Innovation

Because the design document lays everything out in one place, it provides a clearer view when making comparisons and evaluating performance. Team members have a visual representation of current operations and can use it to brainstorm new opportunities for innovation.

Slite's free software design documentation template

When looking for a software design document template, one of the most important things to keep in mind is collaboration. As mentioned above, the best software design documentation is written collaboratively, and you'll need to find a platform that facilitates team members working with each other effectively.

That's where Slite comes in. We have a software design doc template that's perfect for all your software project needs. It's free, highly customizable, looks sleek across different devices and browsers, and is easy for anyone to use.

If you're a developer, software engineer, or working on a software engineering team, our software design documentation template is a dream come true.

How to Write a Software Design Document Using our Awesome Template

Creating an SDD is no walk in the park, even for experienced managers. Slite's software design specification template makes writing up a project plan far smoother. Now that you know the essential components, let's cover how to write a software design document.

Title and Document Description

The title and brief description are written on the design documentation template in the default form. You and your team can customise the supporting content to express the aim and summary of the document. This introduction section should be crisp.


Describe what the software will achieve and the problems it will solve. Use visual aids like infographics or even videos here. For text, we recommend using a bulleted or listed format for clarity and scannability.

Problem Statement

What problems will this software solve for users, and what makes it unique? In this section of the system design document template, provide a clear explanation and predict how the system will provide valuable solutions.

How will it work?

Now for the fun part of the detailed design document template: describe how the software accomplishes said problem-solving and explain the features users will interact with. What would a typical user experience look like? How will each feature work? How will our end-user likely use every feature? How will they impact interface design? What data structure will we use under the hood?

Many teams use visual aids to illustrate these things and highlight beneficial UI-UX attributes.

Development Timeline

Milestones should be accompanied by a timeline so that team members understand their expectations and stakeholders remain informed. This could be sorted into weeks, months, or quarters, and should be flexible enough to accommodate changes.

Slite's technical design document template has a chronology section so you don't have to watch tutorials or build complicated calendars to map deliverables.

How Do We Measure Success?

Of course, KPIs and OKRs should be established early on. They can be altered occasionally, but in general, they align with overarching goals and allow teams to spot weaknesses or mitigate risks. Our solution design document template recommends these measurements in a bulleted list, as KPIs should be easily read and understood.

Launch Plan

Launch plan describes how the product will be delivered to customers, including the sign-up process and marketing tactics. Also important to note - how do you plan to repair problems that may arise during launch, and how long will that take? This isn’t found is some SDDs where product, GTM, and dev team work in silos. Depending on your team’s working style, feel free to include/delete it from your doc.

Get our design document template

Getting Started!

From our point of view, every software developer needs great software design documentation skills in their repertoire. If you're ready to write one for your product or software system start by:

Brainstorming With Your Team

When beginning the development of a software or application design documentation, make sure that you get started on a collaborative document. It might feel like a lot of work and meetings early on, but you'll be thankful that you did so further down the road. You'll be able to collect early suggestions and feedback from key team members and establish team workflows that'll serve you well throughout your development process.

Make Your Document Visual & Concise

You'll want your software design document to look like something that someone would want to read. Staring at a page full of text isn't exactly enticing. Be sure to include visual elements when writing about your software project (think photos, charts, and diagrams). This makes your documentation easier to read and can actually help you explain yourself (and the proposed solution) better. If you use a design documentation template like Slite's, you'll enjoy smart prompts for sections that use media and visual aids.

Keep Your Goal In Mind

An excellent software design document has one objective: if someone reads your SDD and isn't able to talk to you in-person or ask any questions, they shouldn't have any trouble getting started developing the piece of software right away. Although this is unlikely to happen in reality, keeping this in mind when writing your document or using design document templates will steer you in the right direction.

Be Clear

Last but not least, make sure to write clearly when writing your software design document. Even if you're using the most solid solution design document template, keep in mind that it should be as accessible as possible. Don't use unnecessarily complicated language, and simplify whenever you can.

Design docs aren't always the easiest read, so this ensures that everyone from a client to a graphic designer to a software developer can read through it and understand the gist.

Remember, technical documentation literally defines your product

Voila! It looks like you're ready to write a high-level software design document. Once written, it’ll help your team make better decisions and better plans. In fact, you should actively encourage every key stakeholder to pitch in their thoughts on the first draft. Since an SDD is iterative in nature, let people work on it in real-time. It doesn’t matter if you’re building for iOS or Windows, your SDD will guide your strategy every step of the way.

If you need guidance, refer back to this article as needed and get ready to soak in the benefits of this effective software documentation tool.

Click here to try Slite's Software Design Documentation Template

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