Devin vs JetBrains AI / Junie

Devin vs JetBrains AI / JunieComparisonUpdated 2026-03-16

SUMMARY

Devin (Agent) uses markdown configuration while JetBrains AI / Junie (IDE) 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	Devin	JetBrains AI / 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	✗	.aiignore
IDE integration	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	JetBrains AI / Junie
Settings / configuration	.devin/wiki.json	.noai

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

JetBrains AI / Junie

.aiassistant/rules/*.md

markdown

# Kotlin Conventions

## Language Features
- Use Kotlin 2.x with coroutines for async work
- Prefer data classes for DTOs and value objects
- Use sealed classes/interfaces for domain errors
- Extension functions over utility classes

## Spring Boot
- Constructor injection (no field injection)
- Use @ConfigurationProperties over @Value
- Prefer WebFlux for reactive endpoints
- Use Spring Security with method-level security

## Testing
- JUnit 5 with Kotest assertions
- MockK for mocking (not Mockito)
- Testcontainers for integration tests
- Use @Nested for test organization

KEY DIFFERENCES

1. Hierarchy support

Devin: Supported. JetBrains AI / Junie: Not supported.

2. Subdirectory scoping

Devin: Supported. JetBrains AI / Junie: Not supported.

3. Ignore file

Devin: Not supported. JetBrains AI / Junie: .aiignore.

4. IDE integration

Devin: Agent. JetBrains AI / Junie: Supported.

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use Devin, configure AGENTS.md. If you use JetBrains AI / Junie, configure .aiassistant/rules/*.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