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SideCar — AI Coding Assistant for VS Code

SideCar is a free, self-hosted VS Code extension that serves as a drop-in replacement for GitHub Copilot and Claude Code. Use local Ollama models, the Anthropic API, OpenAI, Fireworks AI, OpenRouter, Google Gemini, Groq, Kickstand (self-hosted), or any OpenAI-compatible server (LM Studio, vLLM, llama.cpp) for AI-powered coding — with full agentic capabilities, inline completions, and tool use.

A free, open-source, local-first autonomous AI agent for coding. Full agent loop, not just chat. No subscriptions, no data leaving your machine.

SideCar will always be free, tips not required but appreciated.

Why SideCar?

Most local AI extensions for VS Code are chat wrappers or autocomplete plugins. SideCar is a full agentic coding assistant — closer to Claude Code or Cursor than to a chatbot, but free, open-source, and model-agnostic.

vs. Local Extensions

Capability	SideCar	Continue	Llama Coder	Twinny
Autonomous agent loop	Yes	Yes	Partial	No
File read/write/edit tools	Yes	Yes	Yes	No
Run commands & tests	Yes (persistent shell)	Yes	Yes	No
Web search	Yes (DuckDuckGo / Tavily / Brave)	Yes	Yes	No
Security & secrets scanning	Yes (Problems panel)	Partial	No	No
MCP server support	Yes	Yes	No	No
Git integration (commit, PR, releases)	Yes	Partial	No	No
Diff preview & undo/rollback	Yes	Yes	No	No
Plan mode	Yes	Yes	No	No
Review mode (accept/discard per file)	Yes	Partial	No	No
Pending-change file decorations	Yes	No	No	No
Activity-bar review badge	Yes	No	No	No
Native lightbulb code actions	Yes	Partial	No	No
Built-in skills (8)	Yes	Yes	No	No
Tree-sitter AST parsing	Yes	Yes	No	No
Codebase indexing	Yes	Yes	No	No
Spending budgets	Yes	No	No	No
Session spend tracker (status bar)	Yes	No	No	No
Hybrid cost-aware delegation	Partial	No	No	No
Getting-started walkthrough	Yes	No	No	No
Conversation steering (type while processing)	Yes	No	No	No
Free & open-source	Yes	Yes	Yes	Yes

vs. Pro Tools

Capability	SideCar	Copilot	Cursor	Claude Code
Autonomous agent loop	Yes	Yes	Yes	Yes
Model agnostic (any provider)	Yes	Partial	Partial	No
Fully offline / self-hosted	Yes	No	No	No
HuggingFace model install	Yes	No	No	No
Custom skills system	Yes	Yes	Yes (.cursorrules)	Yes
Context compaction (manual + auto)	Yes	Yes	Yes	Yes
Spending budgets & cost tracking	Yes	Yes	Yes	Yes
Hybrid local-worker delegation	Partial	No	No	No
Prompt pruner & pre-request caching	Yes	No	No	Partial
Plan-then-execute mode	Yes	Yes	Yes	Yes
Review mode (batch diff review)	Yes	No	Partial	No
Native Problems panel integration	Yes	No	No	No
Status bar health indicator	Yes	Partial	No	No
Getting-started walkthrough	Yes	Yes	No	No
Native modal approval for destructive tools	Yes	No	No	Partial
Conversation steering (type while processing)	Yes	No	Yes	Yes
Works in your existing VS Code	Yes	Yes	No (fork)	Yes (extension + CLI)
Monthly subscription	Free	$10-39/mo	from $20/mo	Usage-based / from $20/mo

What sets SideCar apart

True agentic autonomy — reads code, edits files, runs tests, and iterates until the task is done across cautious / autonomous / manual / plan / review / audit modes.
No vendor lock-in — Ollama, Anthropic, OpenAI-compatible (LM Studio, vLLM, OpenRouter), Kickstand, or GGUF directly from HuggingFace.
Feels first-party — status bar health indicator, native error toasts, lightbulb code actions, Problems panel integration, file decorations, activity-bar badge, and a SideCar: command palette category.
Hybrid cost-aware — Anthropic prompt caching + 90%-reduction prompt pruner + delegate_task to a local Ollama worker + session spend tracker + daily/weekly budgets + architect/editor model split (sidecar.editorModel) that auto-routes execution turns to a faster/cheaper model.
Security from the ground up — OS keychain key storage, secrets detection, vuln scanning, path traversal protection, workspace hook warnings, macOS Seatbelt sandbox for agent shell commands.
Extensible — MCP (stdio / HTTP / SSE), custom skills via markdown, 8 built-in skills, NoSQL quick-install for MongoDB + Redis.
Production-grade safety — review mode, audit mode (atomic flush), shadow workspaces, completion gate, cycle detection, stub validator, regression guards.

Features

Feature	Description
65 built-in tools	File ops, shell, git, web search, database (SQLite/PG/MySQL/DuckDB), screenshot, doc-to-test synthesis, code profiling, LaTeX compilation, MCP task delegation, and more — full list
Review / Audit modes	Buffer all writes in-memory; review per-file diffs before anything touches disk. Audit adds atomic flush + deletion coverage
Shadow Workspaces	Run tasks in an ephemeral `git worktree` — main tree untouched until you accept
Typed Sub-Agent Facets	Dispatch named specialists (`test-author`, `security-reviewer`, etc.) in parallel, each with its own tool allowlist and preferred model
Fork & Parallel Solve	`/fork <task>` runs N parallel agent approaches; pick-the-winner review UI
NotebookLM research mode	`/notebook` — source-grounded chat with mandatory inline citations and five study-aid generators
Project Knowledge Index	Semantic search over every function/class in your workspace via tree-sitter + MiniLM embeddings; chunk-level retrieval for prose docs
Active file context bar	Pill above the chat input — one click includes or excludes the currently open file from agent context
Adversarial Critic	Second LLM call after every edit that finds bugs, regressions, and security issues — blocks the turn on high-severity findings
Completion gate	Blocks the agent from declaring done until lint and colocated tests for edited files have actually run
SIDECAR.md	Path-scoped project instructions — sections inject only when the active file matches their `@paths` glob; per-directory files cascade root-to-leaf; falls back to `AGENTS.md` / `CLAUDE.md` / `.cursorrules` when no SIDECAR.md is present
DESIGN.md	Always-injected architecture / style guide — place `.sidecar/DESIGN.md` (or `DESIGN.md`) to keep domain knowledge in every system prompt without SIDECAR.md boilerplate
Inline completions	Copilot-style autocomplete via Ollama FIM or Anthropic (opt-in via `sidecar.enableInlineCompletions`)
Inline chat	`Cmd+I` — edit code in place; lightbulb integration surfaces Fix / Explain / Refactor on diagnostics
Model Arena	`/arena` opens a side-by-side panel comparing 2–4 models on the same prompt with live ELO ratings; `/arena agent` runs a task through different models via fork dispatch
Selective regeneration	Select any text in an assistant response → a bar appears to rewrite just that section with optional instruction, in-place
Background agents	`/bg <task>` spawns parallel autonomous agents with a status dashboard; toast notification + status bar spinner on completion
External context providers	Pull live GitHub Issues, Linear, or Jira tickets into every agent system prompt via `sidecar.contextProviders`
macOS Seatbelt sandbox	`sidecar.sandbox.enabled` wraps agent shell commands with a deny-default SBPL profile — writes restricted to the workspace + `/tmp` + build caches
Dependency Drift Alerts	Scans `package.json`, `requirements.txt`, `Cargo.toml`, and `go.mod` for outdated and vulnerable deps — CVE/GHSA IDs from the OSV API surface in the Problems panel; `check_dependencies` agent tool for on-demand reports
Security scanning	Secrets, SQL injection, XSS, eval — findings in VS Code Problems panel (`source:sidecar-*`)
Doc sync	Checks JSDoc `@param` staleness and README call-site arity on every save
MCP	stdio / HTTP / SSE transports, per-server tool allowlist, `sidecar.noSql.install` for one-click MongoDB + Redis
Skills	8 built-in skills (review-code, debug, refactor, write-tests, break-this, explain-code, create-skill, mcp-builder) + custom markdown skills
Slash commands	`/model`, `/fork`, `/notebook`, `/bg`, `/pr`, `/review`, `/ci`, `/memories`, `/commit`, `/doc`, `/spec`, `/revise`, and 25+ more with autocomplete

Requirements

Visual Studio Code 1.88.0 or later
Ollama installed and in your PATH (for local models only)

Getting Started

Ollama (local, free)

Install Ollama if you haven't already
Install the SideCar extension
Click the SideCar icon in the activity bar
Start chatting — SideCar launches Ollama automatically and downloads a starter model

Recommended models: qwen3-coder:30b (coding), gemma4:e4b (fast + accurate), ministral-3:latest (best agentic score at 6 GB)

Anthropic (Claude)

Click the ☰ menu in the chat header → Anthropic Claude under Backend
SideCar prompts for your API key on first switch — paste it and you're done

Or manually: sidecar.baseUrl = https://api.anthropic.com, run SideCar: Set / Refresh API Key, set sidecar.model = claude-sonnet-4-6.

SideCar uses Anthropic's prompt caching automatically — subsequent turns in a session cost ~90% less on input tokens.

OpenAI

Set sidecar.baseUrl to https://api.openai.com
Run SideCar: Set / Refresh API Key and paste your OpenAI key
Set sidecar.model to gpt-5 (recommended — higher TPM than mini models)

Note: gpt-4o-mini and gpt-4.1-mini share a 200K TPM org-level cap. At ~23K tokens per request (system prompt + tools), the budget exhausts after ~8 requests. Use gpt-5 or a model with a higher TPM allocation.

Fireworks AI

Fireworks offers fast inference for large open-source models including DeepSeek and Llama variants.

Set sidecar.baseUrl to https://api.fireworks.ai/inference
Run SideCar: Set / Refresh API Key and paste your Fireworks key
Set sidecar.model to accounts/fireworks/models/deepseek-v4-pro (recommended)

OpenRouter

OpenRouter provides a single API key for 100+ models across providers.

Set sidecar.baseUrl to https://openrouter.ai/api
Run SideCar: Set / Refresh API Key and paste your OpenRouter key
Set sidecar.model to e.g. x-ai/grok-3-mini or google/gemini-2.5-flash

Google Gemini

Set sidecar.baseUrl to https://generativelanguage.googleapis.com/v1beta/openai
Run SideCar: Set / Refresh API Key and paste your Gemini API key
Set sidecar.model to gemini-2.5-flash

Groq

Groq offers very fast inference for open-source models via their LPU hardware.

Set sidecar.baseUrl to https://api.groq.com/openai
Run SideCar: Set / Refresh API Key and paste your Groq key
Set sidecar.model to e.g. llama-3.3-70b-versatile

Note: Groq's free tier (12K–30K TPM) is exhausted after 1–2 requests from SideCar's system prompt + tool schemas. A paid tier is required for reliable use.

Kickstand (self-hosted manager)

Kickstand is a self-hosted model manager that wraps Ollama with a management API, model registry, and load/unload controls.

Run Kickstand locally — it auto-generates a bearer token at ~/.config/kickstand/token
Set sidecar.baseUrl to your Kickstand URL (default http://localhost:4000)
SideCar reads the token file automatically — no API key prompt needed

Other OpenAI-compatible servers

LM Studio, vLLM, llama.cpp, and other OpenAI-compatible servers work out of the box:

Set sidecar.baseUrl to your server URL (e.g. http://localhost:1234)
Set sidecar.model to the model name on your server
Run SideCar: Set / Refresh API Key if your server requires authentication

SideCar auto-detects the provider from the URL. Override with sidecar.provider: "openai" if needed.

VS Code Copilot Chat & Agents Window

SideCar registers as a native VS Code chat participant — type @sidecar in the Copilot Chat panel to talk to your configured backend without opening the SideCar sidebar. Slash commands /review, /fix, /explain, and /commit-message are available.

VS Code Agents Window (Preview): To use SideCar in the dedicated Agents Window, add the following to your VS Code settings.json:

"extensions.supportAgentsWindow": {
    "nedonatelli.sidecar-ai": true
}

The extension must be installed in your default VS Code profile.

Keyboard Shortcuts

Shortcut	Action
`Cmd+Shift+I` / `Ctrl+Shift+I`	Toggle SideCar chat panel
`Cmd+I` / `Ctrl+I`	Inline chat (edit code in place)
`Cmd+L` / `Ctrl+L`	Clear chat
`Cmd+Shift+U` / `Ctrl+Shift+U`	Undo all AI changes
`Cmd+Shift+E` / `Ctrl+Shift+E`	Export chat as Markdown

Extension Settings

Core settings — full reference at nedonatelli.github.io/sidecar/settings.

Setting	Default	Description
`sidecar.baseUrl`	`http://localhost:11434`	API base URL
`sidecar.model`	`qwen3-coder:30b`	Model for chat
`sidecar.agentMode`	`cautious`	`cautious` / `autonomous` / `manual` / `plan` / `review` / `audit` or a custom mode name
`sidecar.agentMaxIterations`	`50`	Max agent loop iterations
`sidecar.agentMaxTokens`	`200000`	Max tokens per agent run
`sidecar.mcpServers`	`{}`	MCP server definitions (or use `.mcp.json`)
`sidecar.toolPermissions`	`{}`	Per-tool overrides: `allow` / `deny` / `ask`
`sidecar.hooks`	`{}`	Pre/post execution hooks per tool
`sidecar.completionGate.enabled`	`true`	Block agent finish until lint + tests pass
`sidecar.enableInlineCompletions`	`false`	Copilot-style autocomplete (opt-in)
`sidecar.mcpDelegation.enabled`	`false`	Enable `delegate_to_mcp` tool (agent → MCP server)
`sidecar.mcpDelegation.allowedServers`	`[]`	Allowlist of servers `delegate_to_mcp` may target (empty = all)
`sidecar.mcpServer.enabled`	`false`	Expose SideCar's agent loop as a local MCP server
`sidecar.mcpServer.port`	`3457`	Port for the SideCar MCP server (127.0.0.1 only)
`sidecar.mcpServer.requireAuth`	`false`	Require bearer token for inbound MCP requests
`sidecar.dailyBudget`	—	Daily spend cap in USD (paid backends)
`sidecar.weeklyBudget`	—	Weekly spend cap in USD (paid backends)

API keys are stored in VS Code SecretStorage (OS keychain) — set via SideCar: Set / Refresh API Key, never in plaintext settings.

Documentation

Full documentation: nedonatelli.github.io/sidecar

SECURITY.md — threat model, secret-pattern catalog, vulnerability disclosure
docs/extending-sidecar.md — skills, custom tools, MCP servers, policy hooks
CHANGELOG.md — per-release notes
Architecture diagrams: agent loop · tool dispatch · context pipeline · MCP lifecycle

Support & Contact

Bug reports & feature requests: GitHub Issues
Security issues: private disclosure via SECURITY.md — please don't open public issues for vulnerabilities
Email: sidecarai.vscode@gmail.com
Documentation: nedonatelli.github.io/sidecar

Disclaimer

SideCar is an independent project by Nicholas Donatelli and is not affiliated with, endorsed by, or sponsored by Ollama, Anthropic, Meta, Mistral AI, Google, GitHub, or any other company. All product names are trademarks of their respective holders.

License

MIT