Documents significant architectural and technical decisions with full context, alternatives considered, trade-offs analyzed, and consequences understood. Creates a decision trail that helps teams understand why decisions were made. Use when choosing between technology options, making infrastructure decisions, establishing standards, migrating systems, or when user mentions ADR, architecture decision, technical decision record, or decision documentation.
Each ADR captures: Context (what situation necessitates this decision), Decision (what we're choosing), Alternatives (other options considered), Consequences (trade-offs and implications), and Status (proposed, accepted, deprecated, superseded).
Quick Example:
# ADR-042: Use PostgreSQL for Primary Database
**Status:** Accepted
**Date:** 2024-01-15
**Deciders:** Backend team, CTO
## Context
Need to select primary database for new microservices platform.
Requirements: ACID transactions, complex queries, 10k+ QPS at launch.
## Decision
Use PostgreSQL 15+ as primary relational database.
## Alternatives Considered
- MySQL: Weaker JSON support, less robust constraint handling
- MongoDB: No ACID across documents, eventual consistency issues
- CockroachDB: Excellent but adds operational complexity we can't support yet
## Consequences
✓ Strong consistency and data integrity
✓ Excellent JSON support for semi-structured data
✓ Team has deep PostgreSQL experience
✗ Vertical scaling limits (will need read replicas at 50k+ QPS)
✗ More complex to shard than DynamoDB if we need it
Copy this checklist and track your progress:
ADR Progress:
- [ ] Step 1: Understand the decision
- [ ] Step 2: Choose ADR template
- [ ] Step 3: Document the decision
- [ ] Step 4: Validate quality
- [ ] Step 5: Deliver and file
Step 1: Understand the decision
Gather decision context: what decision needs to be made, why now, who decides, constraints (budget, timeline, skills, compliance), requirements (functional, non-functional, business), and scope (one service vs organization-wide). This ensures the ADR addresses the right problem.
Step 2: Choose ADR template
For technology selection (frameworks, libraries, databases) → Use resources/template.md. For complex architectural decisions with multiple interdependent choices → Study resources/methodology.md. To see examples → Review resources/examples/ (database-selection.md, microservices-migration.md, api-versioning.md).
Step 3: Document the decision
Create adr-{number}-{short-title}.md with: clear title, metadata (status, date, deciders), context (situation and requirements), decision (specific and actionable), alternatives considered (with pros/cons), consequences (trade-offs, risks, benefits), implementation notes if relevant, and links to related ADRs. See Common Patterns for decision-type specific guidance.
Step 4: Validate quality
Self-check using resources/evaluators/rubric_adr_architecture.json. Verify: context explains WHY, decision is specific and actionable, 2-3+ alternatives documented with trade-offs, consequences include benefits AND drawbacks, technical details accurate, understandable to unfamiliar readers, honest about downsides. Minimum standard: Score ≥ 3.5 (aim for 4.5+ if controversial/high-impact).
Step 5: Deliver and file
Present the completed ADR file, highlight key trade-offs identified, suggest ADR numbering if not provided, recommend review process for high-stakes decisions, and note any follow-up decisions needed. Filing convention: Store ADRs in docs/adr/ or architecture/decisions/ directory with sequential numbering.
For technology selection:
For architectural changes:
For standards and conventions:
For deprecations:
Do:
Don't:
resources/template.mdresources/methodology.mdresources/examples/database-selection.md, resources/examples/microservices-migration.md, resources/examples/api-versioning.mdresources/evaluators/rubric_adr_architecture.jsonADR Naming Convention: adr-{number}-{short-kebab-case-title}.md
adr-042-use-postgresql-for-primary-database.md