Run Aider on a Local Model — Pair-Program Offline on Your Mac

Aider — the terminal pair-programmer — pointed at a model on your own Mac. Two env vars and it reads, edits, and rewrites your files locally. Private, offline, no per-token bill.

Aider is a terminal-first pair-programmer: it reads your file, sends it to the model with a plain-English instruction, and applies the returned edit blocks locally. It drives models through LiteLLM, so any OpenAI-compatible endpoint works — including a rapid-mlx server on your own Mac.

Fourth in the series on running your favorite agent locally (after Claude Code, Cursor, and Codex). About five minutes.

• Your code stays local. Aider stops sending your files to the cloud.
• No meter. Edit all day for the cost of electricity.
• Forgiving with small models. Aider uses SEARCH/REPLACE edit blocks, not function calling — so even reasoning-only models pass. The signal is "did it rewrite the file correctly," and that works broadly.

The whole thing

1. pip install aider-chat
2. brew install rapid-mlx → rapid-mlx serve qwen3.6-35b-4bit
3. export OPENAI_API_BASE=http://localhost:8000/v1

1 · Install Aider + rapid-mlx

pip install aider-chat
brew install rapid-mlx    # in Homebrew core — no tap, no trust

2 · Serve a model that fits your Mac

rapid-mlx serve qwen3.6-35b-4bit

3 · Point Aider at it

Set two env vars, then run Aider on a file:

export OPENAI_API_BASE=http://localhost:8000/v1
export OPENAI_API_KEY=not-needed

aider --model openai/qwen3.6-35b-4bit main.py

Prefer per-invocation flags instead of env vars? That works too:

aider \
  --model openai/qwen3.6-35b-4bit \
  --openai-api-base http://localhost:8000/v1 \
  --openai-api-key not-needed \
  main.py

4 · Pair on it

> add input validation to parse_config() and a test for the bad-path

Aider reads main.py, proposes the edit as a diff, and applies it in place — locally.

Honest expectations

A model on your Mac isn't a frontier cloud model, but Aider's plain-text edit format is unusually tolerant — it leans on the model rewriting code, not on brittle tool-call JSON. Great for private/offline edits and the everyday 80%; point --model back at a cloud provider for the hard 20%.

Where to go next

• Full Aider guide — the LiteLLM openai/ prefix, recommended aliases, and edit-format notes.
• Claude Code → local · Cursor → local · Codex → local
• Install rapid-mlx — Homebrew or one curl. Apache 2.0.