Aider vs Codex CLI
Aider and Codex CLI side by side: what each one is, verified plan pricing and install commands where we have them, and the full review of each.
Aider
Open-source AI pair programming in your terminal. Works with any LLM - Claude, GPT, Gemini, local models. Git-aware editing with automatic commits.
Codex CLI
OpenAI's open-source (Apache-2.0) terminal coding agent, built in Rust. Included with ChatGPT Plus from $20/mo or usable with an API key. Defaults to GPT-6.1 Sol.
At a glance
| Field | | |
|---|---|---|
| Category | AI Coding | AI Coding |
| Website | aider.chat | github.com |
| Pricing | Free and open source (Apache-2.0); No paid tier - bring your own API keys and pay your LLM provider directly | Plus - $20/mo: Codex in the CLI, IDE extension, web, and iOS, plus cloud code review and Slack; Pro - $100, $200, or $500/mo: everything in Plus with no five-hour limit; Ultrafast mode on Pro $500; Business - $20/user/mo billed annually ($25 monthly), 2+ users; Enterprise and Edu - contact sales; API key - pay per token at OpenAI API rates; no cloud features; Free and Go ($8/mo) - GPT-6 Luna in the desktop app only, subject to rollout |
| Install | curl -LsSf https://aider.chat/install.sh | sh or uv tool install --force --python python3.12 --with pip aider-chat@latest or pipx install aider-chat | curl -fsSL https://chatgpt.com/codex/install.sh | sh or npm install -g @openai/codex or brew install --cask codex |
| Models | Aider connects to most LLMs - Anthropic, OpenAI, Gemini, DeepSeek, xAI, OpenRouter, Azure, Bedrock, Vertex AI, GitHub Copilot, and local models through Ollama, LM Studio or any OpenAI-compatible API. You choose the model with --model at startup (for example aider --model sonnet --api-key anthropic=<key>) or switch mid-session with /model, and its own LLM leaderboards rank which models edit code best. | GPT-6.1 Sol is the default as of CLI 0.161.0, with GPT-6 Astra, GPT-6 Sol, and GPT-6 Luna also available on ChatGPT plans. API-key sessions get whichever models the key can access, and custom Responses-compatible providers can be configured. |
| Last verified | October 17, 2026 | October 17, 2026 |
In Depth
Aider
Aider is an open-source terminal-based pair programming tool that connects to any LLM provider. You add files to the chat, describe changes, and Aider edits them directly in your repo with clean diffs. It understands your git history and automatically creates well-formatted commits for every change. The repository map feature lets it understand code structure across large projects without stuffing everything into the context window. It supports Claude, GPT, Gemini, and local models via Ollama or LM Studio. Aider publishes its own code-editing leaderboards across models and has an active open-source community.
Codex CLI
Codex CLI is OpenAI's coding agent for your own machine. Run `codex` in a repository and it opens a full-screen terminal UI where it reads the code, proposes and applies edits, runs commands inside a sandbox with approval controls, and keeps a resumable session history. It is open source under Apache-2.0 and written in Rust, and the same agent also ships as an IDE extension (VS Code, Cursor, Windsurf), a desktop app (`codex app`), and a scriptable `codex exec` mode for CI. Sign in with ChatGPT to use the usage allowance on a Plus, Pro, Business, Edu, or Enterprise plan, or sign in with an API key and pay standard API rates instead (API-key sessions skip the cloud features such as GitHub code review and Slack). Project instructions live in AGENTS.md, and MCP servers, skills, plugins, and subagents extend what it can do. OpenAI ships CLI releases fast - four landed between October 1 and October 8, 2026 - so the changelog is worth watching. Pick Codex CLI over Codex cloud when local services, your own toolchain, and immediate feedback matter more than async background runs.
FAQ
Answers taken from each tool's verified fact sheet, with the date it was last checked.
How much does Aider cost?
As of October 17, 2026: Free and open source (Apache-2.0); No paid tier - bring your own API keys and pay your LLM provider directly. Source: Aider installation docs, Aider release history, Aider-AI/aider releases, Aider-AI/aider README and license, Connecting to LLMs.
How do I install Aider?
Official install commands as of October 17, 2026: curl -LsSf https://aider.chat/install.sh | sh or uv tool install --force --python python3.12 --with pip aider-chat@latest or pipx install aider-chat.
Which models does Aider use?
As of October 17, 2026: Aider connects to most LLMs - Anthropic, OpenAI, Gemini, DeepSeek, xAI, OpenRouter, Azure, Bedrock, Vertex AI, GitHub Copilot, and local models through Ollama, LM Studio or any OpenAI-compatible API. You choose the model with --model at startup (for example aider --model sonnet --api-key anthropic=<key>) or switch mid-session with /model, and its own LLM leaderboards rank which models edit code best.
How much does Codex CLI cost?
As of October 17, 2026: Plus - $20/mo: Codex in the CLI, IDE extension, web, and iOS, plus cloud code review and Slack; Pro - $100, $200, or $500/mo: everything in Plus with no five-hour limit; Ultrafast mode on Pro $500; Business - $20/user/mo billed annually ($25 monthly), 2+ users; Enterprise and Edu - contact sales; API key - pay per token at OpenAI API rates; no cloud features; Free and Go ($8/mo) - GPT-6 Luna in the desktop app only, subject to rollout. Source: openai/codex README, Codex pricing, Codex changelog.
How do I install Codex CLI?
Official install commands as of October 17, 2026: curl -fsSL https://chatgpt.com/codex/install.sh | sh or npm install -g @openai/codex or brew install --cask codex.
Which models does Codex CLI use?
As of October 17, 2026: GPT-6.1 Sol is the default as of CLI 0.161.0, with GPT-6 Astra, GPT-6 Sol, and GPT-6 Luna also available on ChatGPT plans. API-key sessions get whichever models the key can access, and custom Responses-compatible providers can be configured.
