Aider vs JunieComparisonUpdated 2026-03-16
SUMMARY
Aider (CLI) uses markdown configuration while Junie (Agent) uses markdown. They differ on 4 of 11 compared features. Both tools provide AI-assisted development but take different approaches to project configuration.
FEATURE COMPARISON
| Feature | Aider | Junie |
|---|---|---|
| Config format | markdown | markdown |
| Hierarchy support | ✗ | ✗ |
| Global config | ✓ | ✗ |
| Project config | ✓ | ✓ |
| Subdirectory scoping | ✓ | ✗ |
| File inclusion / imports | ✗ | ✗ |
| Ignore file | .aiderignore | ✗ |
| IDE integration | CLI | Agent |
| Schema / structure | Free-form (Markdown) | Free-form (Markdown) |
| Git committed | ✓ | ✓ |
| Encoding | UTF-8 | UTF-8 |
FILE MAPPING
| Purpose | Aider | Junie |
|---|---|---|
| Project instructions | CONVENTIONS.md | .junie/guidelines.md |
SIDE-BY-SIDE CODE SAMPLES
Aider
CONVENTIONS.md
markdown
# Project Conventions
## Language
- TypeScript strict mode, no `any` types
- Prefer const over let, never use var
- Use template literals over string concatenation
## Architecture
- Feature-based folder structure under src/features/
- Each feature exports through an index.ts barrel file
- Shared utilities go in src/lib/
## Error Handling
- Use Result<T, E> pattern for expected failures
- Throw only for programmer errors
- Always log errors with structured context
## Testing
- Colocate tests next to source files (*.test.ts)
- Use factories for test data, not fixtures
- Integration tests in __tests__/ directories
Junie
.junie/guidelines.md
markdown
# Project Guidelines
## Language & Framework
- Kotlin with Spring Boot 3.x
- Gradle with Kotlin DSL
- JDK 21 with virtual threads
## Architecture
- Hexagonal architecture (ports & adapters)
- Domain events for cross-module communication
- CQRS for read-heavy endpoints
## Code Standards
- Follow Kotlin coding conventions
- Use data classes for DTOs
- Prefer sealed classes for domain errors
- Extension functions over utility classes
## Testing
- JUnit 5 with Kotest assertions
- Testcontainers for integration tests
- MockK for mocking (not Mockito)
## Build & Run
- Build: ./gradlew build
- Test: ./gradlew test
- Run: ./gradlew bootRun
KEY DIFFERENCES
Aider: Supported. Junie: Not supported.
Aider: Supported. Junie: Not supported.
Aider: .aiderignore. Junie: Not supported.
Aider: CLI. Junie: Agent.
WHICH SHOULD I USE?
Choose based on your IDE/CLI preference. If you use Aider, configure .aider.conf.yml. If you use Junie, configure .junie/guidelines.md. Many projects include config files for multiple tools so each team member can use their preferred editor.
PORTABILITY TIP
sync-instructions.sh
bash
# Maintain a single source of truth:
cp AI-INSTRUCTIONS.md CLAUDE.md
cp AI-INSTRUCTIONS.md .cursorrules
cp AI-INSTRUCTIONS.md AGENTS.md
SEE ALSO
File references:
agentconfig.ing2026-03-16COMPARE(1)