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Technical design document template

Six linked documents that take a system from requirements to rollout: the context, the architecture, the data and interfaces, how it runs and fails, and the options you turned down. Download them as Markdown files: they open in any editor, sit next to the code in a repository, draw their diagrams on GitHub and in Obsidian, and import into Nodary as a map.

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6 Markdown files in a .zip, 5 kB

Free, no account, no email. Use it, change it, share it.

Technical design documentContext and requirementsArchitectureData and interfacesOperationsAlternatives and risks

Read every page before you download

The overview fits on one screen and links to five parts, so a reviewer reads the summary, then goes straight to the part they own. Italic lines say what to write; the examples follow one sample feature, share links that expire.

Documents

File Technical design document template/Technical design document.md

Technical design document

How to use this template: italic lines are guidance. Replace them with your own words, then delete them. Values in square brackets are yours to fill in. Keep this page to one screen: a reviewer should know from it what they are approving.

At a glance

FieldThis design
System or feature[Name]
Author[name]
Reviewers[names]
Status[draft, in review, approved, built]
Requirements[link to the PRD]
Target release[date or version]

Summary

Three sentences: what you will build, why, and the one decision a reviewer should look at first.

Example (a sample feature): Share links get an optional end date. Every request checks the date, so a link stops working the moment it ends. A scheduled job revokes expired links every minute; it only cleans up, so a late run changes nothing for the person opening the link.

[Your summary]

Goals and non-goals

  • Goal: [...]
  • Goal: [...]
  • Non-goal: [...]
  • Non-goal: [...]

The rest of the design

Each part is its own document. Link to it rather than copy from it, so every fact lives in one place.

This template is free to use, change and share. It comes from Nodary, where these files import as a map of linked documents.

Download the template6 Markdown files in a .zip, 5 kB

How to use it

  1. Start from the requirements

    Link the product requirements in the context page and list the ones that shape the design. A design that answers no requirement is a refactoring in disguise.

  2. Draw, then write

    Draw the components and the calls between them before the prose. Reviewers spot a missing box faster than a missing paragraph.

  3. Write down what you rejected

    Fill in the alternatives with the options you seriously considered. It saves the review from reopening them one by one.

  4. Update it after the build

    When the code ships, mark what changed from the plan. The next person reads the design to learn how the system works, not how it was imagined.

Import it into Nodary as a map

Nodary is an AI-native workspace where a team’s documents link instead of piling up. Import the .zip and the design arrives with its five parts filed under it, its links kept and its diagram drawn as a Mermaid diagram you can edit. Reviewers comment on a passage or on an element of a diagram, the author asks for an approval, and coding agents such as Cursor, Claude Code or VS Code, connected over MCP, read the design before they write the code.

  1. Open a project’s map and choose Import.
  2. Choose the Folder or ZIP tab, then Choose a ZIP.
  3. Pick the downloaded file, check the tree, and import.

The Free plan holds ten documents per workspace, the project’s own page included: the template’s six leave room for three more. Nodary also has a one-page Technical Design template built in.

Connect Cursor, Claude Code or VS Code to Nodary
A project on Nodary’s map: 43 documents grouped around eight area hubs, linked by hierarchy lines and labeled links, with teammates’ pointers on the map; the sample project shown is a game.

Writing a design document reviewers can approve

A technical design document fails when reviewers cannot tell what they are approving, or when the system it describes is not the one that shipped. These habits prevent both.

Lead with the decision

Say in the summary what you will build and the one choice a reviewer should look at first. Nobody should reach page three to find it.

Draw before you write

A diagram of six boxes and their calls beats six pages of prose, and shows the missing piece at once.

Name what you will not do

Non-goals keep the review on the design at hand instead of the one someone wishes you were writing.

Show the options you turned down

For each significant choice, say what else you considered and why not. Reviewers then argue with your reasons, not with your conclusion.

Plan for failure

Say what happens when each part fails, how you will notice, and how you recover. Operations is part of the design, not an appendix.

Keep it true after the build

Mark what changed during the build and link the decisions behind it. A design that matches the code is documentation; one that does not is a trap.

Questions about technical design documents

What is a technical design document?

A technical design document, or TDD, describes how a system or a feature will be built before the code is written: its context and requirements, its architecture, its data and interfaces, how it is deployed and monitored, the risks and the alternatives considered. Engineers write it so that others can review the approach while it is still cheap to change.

What should a technical design document include?

A summary with goals and non-goals, the current state and the requirements, the components and how they talk to each other, the data model and the APIs, deployment, monitoring, security and failure modes, the alternatives considered, the risks, the rollout plan and the open questions. This template has a document for each group.

What is the difference between a technical design document and a PRD?

The product requirements document says what the feature must do and why. The technical design document says how the system will do it. Write the PRD first, then link it from the design so each requirement can be traced.

When does a change need a design document?

When it touches several components or teams, changes data that already exists, is hard to undo, or carries a risk worth a second pair of eyes. A small change inside one component usually needs a good pull request, not a design document.

Who should review a technical design document?

The engineers who will build and run it, an engineer from each system it touches, and someone responsible for security when it handles personal data or access. Ask for the review early, before most of the code exists.

Do game teams write technical design documents too?

Yes. The game design document template has a technical design part for the engine, targets and pipeline; a large system such as networking, saves or tools deserves a full technical design document of its own, linked from it.

Read next

Keep the design next to the people and agents who build it.

Import the template into Nodary and the design becomes a map that your team and your coding agents read before they change the system. Free with two members, one project and ten documents, no card needed.

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