Codex vs JetBrains AI Assistant / Junie: Side-by-Side Comparison 2026

Codex is an AI agent and a CLI-based coding agent from OpenAI — asynchronous autonomous coding agent. JetBrains AI Assistant / Junie is an editor extension from JetBrains — native ai assistant for jetbrains ides.

Codex🏆 Approved

OpenAI's autonomous coding agent. Available via web, desktop app (macOS), CLI (macOS/Linux/Windows), and VS Code extension.

✓ Code completions
✓ AI chat
✓ Agentic mode
✓ Multi-file editing
✓ Terminal commands

Free / $8/mo · 6 plans

JetBrains AI Assistant / Junie

JetBrains AI Assistant / Junie — AI Code Assistant from JetBrains. IDE-Integrated AI.

✓ Code completions
✓ AI chat
✓ Junie (autonomous agent)
✓ Multi-file editing
✓ Terminal commands

Free / $10/mo · 3 plans

Feature	Codex	JetBrains AI Assistant / Junie
Category	Agent / CLI	Extension
Starting Price	Free	Free
Model Family	GPT / Codex	Multi-model
Open Source	Yes (CLI)	No

Key Differences

Category: Codex is an AI agent and a CLI-based coding agent; JetBrains AI Assistant / Junie is an editor extension.
Starting price: Codex starts at $8/mo; JetBrains AI Assistant / Junie starts at $10/mo.
Model family: Codex uses GPT / Codex; JetBrains AI Assistant / Junie uses Multi-model.
Open source: Codex: Yes (CLI). JetBrains AI Assistant / Junie: No.
Platforms: Codex runs on Linux, Web, Windows (experimental), macOS; JetBrains AI Assistant / Junie runs on Linux, Windows, macOS.
Provider: Codex is built by OpenAI; JetBrains AI Assistant / Junie is built by JetBrains.

Which Should You Choose?

Choose Codex if you want asynchronous coding tasks you can fire off and review when ready. Choose JetBrains AI Assistant / Junie if you want native AI assistance with multi-model choice and agentic capabilities. Read our full reviews to see which fits your workflow.