Devin vs Junie | agentconfig.ing

Devin vs JunieComparisonUpdated 2026-03-16

SUMMARY

Devin (Agent) uses markdown configuration while Junie (Agent) uses markdown. They differ on 2 of 11 compared features. Both tools provide AI-assisted development but take different approaches to project configuration.

FEATURE COMPARISON

Feature	Devin	Junie	Notes
Config format	markdown	markdown
Hierarchy support	✓	✗	Whether config files can be placed at multiple directory levels
Global config	✗	✗	User-wide configuration outside any project
Project config	✓	✓
Subdirectory scoping	✓	✗	Config files in subdirectories that apply only to that subtree
File inclusion / imports	✗	✗	Ability to include or reference other files from config
Ignore file	✗	✗
IDE integration	Agent	Agent
Schema / structure	Free-form (Markdown)	Free-form (Markdown)	Whether config uses structured schema or free-form content
Git committed	✓	✓	Whether primary config files are intended to be version-controlled
Encoding	UTF-8	UTF-8

FILE MAPPING

Purpose	Devin	Junie
Project instructions	AGENTS.md	.junie/guidelines.md

SIDE-BY-SIDE CODE SAMPLES

Devin

AGENTS.md

markdown

# Agent Instructions

## Setup
- Python 3.12 with uv package manager
- PostgreSQL 16 and Redis 7
- Run: uv sync && uv run alembic upgrade head

## Commands
- Dev server: uv run uvicorn app.main:app --reload
- Tests: uv run pytest -x --tb=short
- Lint: uv run ruff check . && uv run mypy .
- Format: uv run ruff format .

## Code Style
- FastAPI with async endpoints
- Pydantic v2 for all schemas
- SQLAlchemy 2.0 async sessions
- Repository pattern for data access

## PR Guidelines
- Keep PRs focused on a single issue
- Add tests for new functionality
- Run the full test suite before submitting

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

1. Hierarchy support

Devin: Supported. Junie: Not supported.

2. Subdirectory scoping

Devin: Supported. Junie: Not supported.

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use Devin, configure AGENTS.md. 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