Cline vs Roo Code vs Aider: Open-Source Coding Agents

Pick Aider if you work in a terminal and want every AI edit to land as its own git commit. Pick Cline if you work in VS Code and want to approve each file edit and shell command before it happens. Pick Roo Code only if you plan to write your own modes, because out of the box it behaves like Cline with more settings. All three are free, Apache 2.0 licensed, and run on an API key you bring, so the software costs nothing and the model provider bills you per token.

These are the agents people reach for when they do not want another subscription, or when they want to point the same tool at Anthropic on Monday and a local model on Tuesday. That flexibility is the whole appeal. It also means the price is open-ended, which is the first thing this page deals with. If you are weighing subscription agents instead, our ranked list of AI coding agents covers Claude Code, Cursor and Windsurf, and Claude Code vs Codex covers the two flat-fee terminal agents.

AI Tools Digest does not make, sell or earn from any of these three tools. The verdicts below are sorted by how you work. None of the three is ranked first.

Cline, Roo Code and Aider compared

Tool	Runs in	Best for	Before an edit or command	Undo	Project rules	Price	Key trade-off
Cline	VS Code and VS Code forks	Developers who want to see and approve every step	Shows a diff and asks, by default; auto-approve is opt-in per action type	Checkpoints after each step, kept outside your git history	.clinerules	Free; you pay your model provider	Clicking approve dozens of times a task, or turning it off and losing the point
Roo Code	VS Code and VS Code forks	Teams that want a planning mode that cannot touch code	Same approval model as Cline, with per-mode file and tool limits	Checkpoints, as in Cline	.roo/rules/ and .roomodes	Free; you pay your model provider	More settings to learn before it does anything Cline does not
Aider	Your terminal, beside any editor	Git-first developers who review commits after the fact	Applies edits straight away and commits them; asks before running a shell command it suggests	/undo reverts the last Aider commit	Any file passed with --read, such as CONVENTIONS.md	Free; you pay your model provider	Skips your pre-commit hooks by default (--git-commit-verify is off)

Details are from each project's documentation as of October 2026. All three move fast, so check the release notes for the version you install.

What you actually pay

The tool costs nothing. Your model provider sends the bill.

Cline and Roo Code send a long system prompt describing their tools on every request, then add whatever files the agent decides to read, and an agentic loop that reads, edits, runs tests and reads again can make a dozen or more model calls for one bug fix. Both extensions show a running API cost for the current task in the panel, which is the number to watch during your first week. Aider is leaner by design. It sends a compact map of your repository built with tree-sitter, plus only the files you have added to the chat with /add, and it prints the tokens sent, tokens received and cost after every message.

Our view: if you code with an agent most of the day, a flat subscription usually wins. Claude Pro is $20 a month, or $17 billed yearly, and includes Claude Code, so heavy daily use on a per-token key can overtake that quickly. The open-source agents win when your use is bursty or your employer already pays for API access. They also win outright if you need a model the subscription tools do not offer, including one running on your own machine through Ollama or LM Studio. Local models cost nothing per token. On multi-step agent work, they are also noticeably weaker than the frontier models, so expect more retries.

Aider in daily use

Aider is the one we would install first, with one setting changed on day one.

Every edit Aider makes becomes a git commit with a message it writes itself. That sounds like noise until you need to back something out. /undo reverts the last Aider commit, git log shows exactly what the model touched and when, and you can squash the lot before you open a pull request. Nothing reaches your branch that git does not know about.

The catch sits in a default. Aider commits with --no-verify unless you set --git-commit-verify, which means your pre-commit hooks (a linter, a secret scanner, whatever you have wired up) do not run on its commits. On a repository where those hooks are the safety net, that is the wrong default. Put git-commit-verify: true in .aider.conf.yml and forget about it. Pre-push hooks are unaffected, since Aider does not push.

The rest is quieter. You choose which files are in play with /add and /drop, which keeps cost down and keeps the model away from files you did not mean to share. --architect splits a request between a reasoning model that plans and a cheaper model that writes the edits. --watch-files lets you leave a comment ending in AI! in your editor and have Aider act on it, which is the closest it gets to an IDE integration. And Aider's maintainer, Paul Gauthier, publishes the polyglot benchmark that many people use to compare models for code editing: 225 Exercism exercises across C++, Go, Java, JavaScript, Python and Rust. That leaderboard is useful even if you never run Aider.

What Aider lacks is a live diff. If you want to watch each change appear in your editor and accept or reject it hunk by hunk, it will feel like working blind.

Cline in daily use

Cline began life as Claude Dev, a VS Code extension for one model, and it still carries that hands-on character. It has two modes. Plan reads your code and talks through an approach without changing anything. Act carries it out, and by default it stops before each file edit to show you a diff, and before each terminal command to ask.

That approval loop is the reason to choose Cline, and also its main cost in patience. A ten-step task means ten decisions. Cline lets you auto-approve by category, so you can let it read files freely and still make it ask before running commands, which is the split we would use on any repository with a database behind it. Checkpoints save the workspace after each step in a separate shadow repository, so you can compare or restore without anything showing up in your own git history.

Cline also has the most polished support for MCP servers of the three, with a marketplace inside the extension. If your agent needs to query a database or drive a browser, Cline gets you there with the least setup.

A note on the name

Roo Code shipped as Roo Cline before it was renamed, which tells you most of what you need to know about where it came from.

Roo Code in daily use

Roo Code started as a fork of Cline, and the shared ancestry shows in the approval prompts and checkpoints. What it adds is modes. It ships with Code, Architect, Ask, Debug and Orchestrator, and each mode can be limited to certain tools and certain files. Architect, for example, can only edit Markdown files by default, so a planning session cannot wander into your source tree. Orchestrator breaks a large task into subtasks and hands each one to the right mode.

You can define your own in .roomodes and commit it, so a team shares the same "reviewer" or "docs writer" mode with the same limits. That is a real reason to choose Roo Code over Cline.

If you will not write a mode, choose Cline.

Where each option fits (and where it does not)

Aider fits developers who live in the terminal and treat git history as the record of what happened. It also tends to run the smallest token bill of the three. It does not fit anyone who wants to approve changes before they reach disk, or a repository that relies on pre-commit hooks, until you turn --git-commit-verify on.

Cline fits VS Code users who want to see every diff and every command first, and anyone wiring an agent to MCP servers. It does not fit long unattended runs, since the approval prompts are the product, and turning them all off removes the reason to pick it.

Roo Code fits teams that want enforced roles, such as a planning mode that cannot edit code or a docs mode limited to Markdown, written down in a file everyone shares. It does not fit a solo developer who wants a working agent in five minutes. Cline gets there with fewer decisions.

Where the alternatives win: a subscription agent such as Claude Code or Codex is usually cheaper for all-day use, and both run headless in CI without extra setup. Cursor and Windsurf give you tab completions, which none of these three offers. For how Claude Code, Cursor and Windsurf handle a gated repository, see Cursor vs Claude Code vs Windsurf for Production Repos. Every comparison we publish is in the article index, and the coding-tool head-to-heads are also collected under comparisons.

Frequently Asked Questions

Which is better, Cline, Roo Code or Aider?

It depends on where you work. Aider is the best fit in a terminal, because every edit becomes a git commit you can review or undo with /undo. Cline is the best fit in VS Code if you want to approve each edit and command first. Roo Code is the best fit for teams that will define custom modes with their own file and tool limits.

Are Cline, Roo Code and Aider free?

Yes. All three are open source under the Apache 2.0 license and free to install. You pay your model provider for the tokens each task uses, or nothing per token if you run a local model through Ollama or LM Studio.

Is Roo Code the same as Cline?

No. Roo Code started as a fork of Cline and shares its approval prompts and checkpoints. It adds built-in modes (Code, Architect, Ask, Debug and Orchestrator) and custom modes defined in a .roomodes file, each of which can be limited to certain tools and files.

Does Aider run my git pre-commit hooks?

Not by default. Aider commits with --no-verify unless you set --git-commit-verify, so linters and other pre-commit hooks are skipped on its commits. Add git-commit-verify: true to .aider.conf.yml to turn them back on.

Is a bring-your-own-key agent cheaper than Claude Code?

For light or occasional use, usually yes. For all-day agent work, usually no: Claude Pro is $20 a month, or $17 billed yearly, and includes Claude Code, while a per-token key has no ceiling. Cline and Roo Code show the running cost of each task, and Aider prints the cost after every message, so a week of normal work will tell you which side of that line you are on.

Can Cline, Roo Code or Aider use local models?

Yes. All three can connect to a model running locally through Ollama or LM Studio, which removes the per-token cost. Local models are weaker at multi-step agent work than frontier models, so expect more retries and smaller tasks.