SHORTLIST
Open-source AI coding tools, and how to audit one in twenty minutes
Both Cline and Aider are Apache-2.0 and free to use, with cost moving to your model provider. Roo Code is the same licence and adds configurable per-mode permissions, but it is the one here where maintenance activity is worth checking before you standardise.
What the licence actually buys you
It buys auditability and the right to fork. It does not buy privacy: an Apache-2.0 client talking to a hosted model still sends your source code to that model's operator.
That distinction is where most "open-source AI tool" comparisons go wrong. The client's licence and the inference path are two separate decisions, and only the second one governs where your code ends up.
The three that qualify
Cline is the largest project of the three by community size, and ships as an extension, a CLI and a desktop app. Aider is the terminal-native option with a commit-per-change workflow. Roo Code is the Cline-lineage fork with configurable modes.
All three are bring-your-own-key. None includes model credits, so budget the inference separately from the tool.
A twenty-minute audit
Read the licence file in the repository, not the marketing page — check whether it is Apache-2.0, MIT, or a custom source-available term.
Search the source for telemetry and analytics calls, then run the tool with outbound traffic logged for one session. Watch for calls on startup and on error paths, which are the easy ones to miss.
Confirm whether the agent executes shell commands by default or only after approval, and whether that setting can be changed by a model rather than by you.
| Tool | Price | Open source | Platforms | Runs commands | Audit log |
|---|---|---|---|---|---|
| Cline | Free / BYO key | Yes | VS Code | Yes | none |
| Aider | Free / BYO key | Yes | macOS | Yes | none |
| Roo Code | Free / BYO key | Yes | VS Code | Yes | none |
FAQ
Are these tools really free?
The clients are. Inference is not. Every tool in this list requires a model, either through a paid API key or a local model that consumes your own hardware. The licence removes the software cost, not the compute cost.
Which one has the safest default behaviour?
Both Cline and Aider gate file writes and command execution behind approval by default. Neither ships an OS-level sandbox, so the approval prompt is the boundary — which means a user who clicks through prompts has no boundary.
Does open source mean I can self-host the model too?
The client can point at a local server, yes. Whether quality is acceptable depends on the model you can run locally; smaller models are noticeably worse at multi-file edits, which is where agent value concentrates.
Last checked 2026-11-02. Prices and feature gates change; each tool page links to its vendor pricing page so you can confirm before committing.