DEV Community

Cover image for How to Write Architecture Decision Records (ADRs) That Your Team Will Actually Read
klority
klority

Posted on

How to Write Architecture Decision Records (ADRs) That Your Team Will Actually Read

#architecture #software #adr #softwareengineering

Every growing software team has had this conversation:

"Why did we choose DynamoDB over PostgreSQL for the billing service two years ago?"

"I think Dave made that decision before he left."

"Is there a doc explaining why?"

"Maybe somewhere in Confluence... or in a PR comment... or an old Slack thread."

Months or years later, nobody remembers the original constraints, what alternatives were evaluated, or what trade-offs were accepted.

The result? Teams either spend weeks reverse-engineering old decisions or repeat the exact same mistakes.

This is why Architecture Decision Records (ADRs) exist.

What is an Architecture Decision Record (ADR)?

An ADR is a lightweight, version-controlled document that captures a single significant architectural decision along with its context and consequences.

Unlike giant 40-page software architecture specifications that rot the moment they are written, ADRs are short, punchy, and immutable:

  • Short: Usually readable in under 3 minutes (1 to 2 pages max).
  • Context-driven: They explain why you chose Option A over Option B at that specific point in time.
  • Living with code: Typically stored directly in your Git repository under /docs/adr/ or in your engineering knowledge base.

The Anatomy of an Effective ADR

The most popular format is based on Michael Nygard’s structure and the MADR (Markdown Architectural Decision Records) standard.

A great ADR consists of five quick sections:

1. Title & Status

  • Title: ADR-004: Adopt Redis for Session Caching
  • Status: Proposed | Accepted | Superseded | Rejected

2. Context

What is the problem we are solving? What constraints (performance, budget, team skill set) are driving this decision? Keep it objective and factual.

3. Decision & Options Considered

What did we decide to do? Which alternatives were evaluated?

  • Option 1: PostgreSQL Unlogged Tables (Rejected due to connection limits)
  • Option 2: Redis Cluster (Accepted)

4. Consequences & Trade-offs

Every architectural decision has trade-offs. Be honest about them:

  • Positive: Sub-millisecond latency, automatic TTL expiration.
  • Negative: Extra infrastructure cost, memory management overhead.

5. Architectural Diagram (Mermaid.js)

A text-only decision is often hard to visualize. Including a quick sequence or architecture diagram makes the workflow instantly clear to new engineers onboarding six months later.

Why Teams Stop Writing ADRs (and How We Fixed It)

If ADRs are so great, why doesn't every team write them consistently?

Because friction kills documentation:

  1. Copy-pasting empty markdown templates feels like a chore.
  2. Drawing diagrams in separate UI tools (like draw.io or Miro) takes too long.
  3. Formatting markdown tables and trade-off matrices by hand is tedious.

To eliminate this friction, we built a free, browser-based generator:

👉 Try the Free ADR & RFC Generator

Built for Speed and Privacy

We designed this tool with three principles for engineers:

  • Zero Sign-Up & No Paywall: Open the page and start drafting immediately.
  • Native Mermaid.js Diagram Support: Generate sequence and system flow diagrams directly alongside your decision.
  • 100% Client-Side Privacy: Your architectural notes and internal system names never leave your browser or hit external servers.
  • 1-Click Markdown Export: Download a standardized .md file ready to commit to your Git repo or paste into your wiki.

How to Introduce ADRs to Your Team

If your team currently documents decisions in Slack or PR comments, here is a simple 3-step rollout:

  1. Keep the bar low: Don't write an ADR for every small bugfix. Only write one when introducing a new library, changing a database, or altering an API contract.
  2. Review them in PRs: Treat ADRs just like code. Propose the decision in a Pull Request and let the team review it asynchronously.
  3. Never delete an ADR: If a decision changes later, don't edit the old file. Create a new ADR (e.g., ADR-012: Replace Redis with Valkey) and mark the old one as Superseded by ADR-012.

Try it out:

Next time your team debates an architecture change in Slack, capture the decision in 5 minutes using the ADR & RFC Generator.

You can also check out our full collection of client-side planning calculators at the Klority Free Agile Tools Hub.

series: Free Developer Tools

Over to you:

How does your team currently document architectural decisions?

  • In Git repositories as Markdown?
  • In Notion / Confluence?
  • Or in Slack threads and PR descriptions?

Drop your thoughts in the comments below! 👇

Top comments (0)