terminalOS

The browser-based terminal workspace built for AI-native developers. One command. Runs locally. Opens in your browser

The Problem

AI coding tools like Claude Code, Aider, and OpenCode are becoming central to how developers work — but your terminal wasn't built for them.

Running an AI session today means:

• No visibility into token consumption — you discover your API bill at the end of the month.
• No way to tell when AI is "thinking" — your terminal looks the same whether AI is running or idle.
• Context switching hell — juggling docs, code files, and multiple AI sessions across different windows.
• Generic terminals that treat AI tool output as noise — no structured parsing, no error surfacing, no smart detection.

You're using a 1980s tool to run 2025 software.

What terminalOS Does

terminalOS is a browser-based terminal multiplexer purpose-built for AI coding workflows. Run it instantly with a single command — no installation, no download. It understands AI tools natively — detecting when they're running, tracking how much you're spending, and giving you a workspace that matches the way AI-assisted development actually works.

Think iTerm2, but redesigned from scratch around Claude Code, Aider, and OpenCode — and running right in your browser.

Core Features

AI-Aware Session Detection

Every terminal pane detects when an AI coding tool is running. A live color-coded badge shows which tool is active with instant visual feedback when a session starts or ends.

| Tool | Badge Color | | ----------- | ---------------- | | Claude Code | Tan #D4A27F | | OpenCode | Blue #7FB5D4 | | Aider | Purple #A27FD4 | | Continue | Green #7FD4A2 |

Detection works by scanning PTY output directly — no process polling, no shell hooks required. A 3-second grace period prevents false positives when TUI input prompts appear at startup.

Real-Time Token Tracking & Cost Estimation

terminalOS parses token usage directly from CLI output — no API key required, no external service. Token counts and estimated USD cost are surfaced in the status bar as you work.

Supported output formats (all tools, automatically detected):

| Format | Example | | -------- | --------------------- | | OpenCode | 64,101 31% | | Generic | ↑ 5.2k tokens | | Claude | tokens used: 12,345 | | Aider | (5.2k tokens) |

Built-in model pricing:

| Model | Price per 1M tokens | | ----------------------- | ------------------- | | Claude Opus 4 / 4.5 | $15.00 | | Claude Sonnet 4.5 / 4.6 | $3.00 | | Claude Haiku 4.5 | $0.80 |

The status bar shows two counters simultaneously: session tokens (focused pane only) and workspace tokens (all panes in the active tab).

API Error Alerts

Detects and surfaces common AI API errors as visual alerts inside the pane — before they silently fail and waste your time:

• Invalid or missing API key
• Model not found (404)
• Authentication token conflicts (ANTHROPIC_AUTH_TOKEN vs ANTHROPIC_API_KEY)

Multi-Pane Workspace

Split your workspace horizontally or vertically into an unlimited 2D pane tree. Run Claude in one pane, your test suite in another, and a markdown doc in a third — all in a single window.

• Drag-to-resize split handles between panes
• Multiple tabs — each with its own independent layout
• Auto-save — layout (splits, ratios, active pane) saved automatically every 500ms
• Full restore — exact layout reconstructed on every launch

Integrated Markdown Editor

A built-in file editor with live preview designed for reviewing AI-generated docs, editing prompts, and working with code files without leaving your terminal.

• Live markdown preview — rendered side-by-side as you type
• Automatic version history — up to 50 snapshots saved per file, with a sidebar panel to browse, preview, and restore any previous version
• Syntax highlighting for 25+ languages (TypeScript, JavaScript, Python, Rust, Go, C/C++, and more)
• File browser — navigate directories, open files with a single click
• File management — create and rename files and folders inline
• Drag-and-drop file operations within the browser

Version History

Every time you save a file, terminalOS captures a snapshot automatically. A version badge (v{n}) appears in the editor header when history exists.

• Auto-save deduplication — identical content is never stored twice
• Manual saves always create a new version; auto-saves are throttled to 2-minute intervals
• Up to 50 versions per file, stored locally in {userData}/md-versions/
• Restore any version from the sidebar panel with a single click

Command Palette

Open anything instantly with ⌘K. A fuzzy-search interface with score-based ranking covers every action in the app — no mouse required.

Available command categories:

• Pane operations (split right, split below, close)
• Tab management (new workspace)
• AI tool launchers (Claude Code, OpenCode, Aider)
• Markdown editor toggle
• Folder and workspace management
• Settings
• Recent folders (up to 10, instantly accessible)

Terminal Engine

Built on XTerm.js with full modern terminal support:

• Full ANSI/256-color/truecolor escape sequence rendering
• 5,000-line scrollback buffer per pane
• Clickable URLs — detected and linked automatically
• In-terminal search — find text within any pane's output
• Auto-resize — panes reflow instantly on window or split resize
• Mouse selection → clipboard — selected text is auto-copied
• Font support: JetBrains Mono, Meslo LGS NF, Hack Nerd Font

Workspace Management

• Root folder — set once, persists across launches
• Git branch — current branch shown in the status bar
• Conda environment — active conda env detected and displayed
• Recent folders — last 10 workspaces accessible from the command palette
• CWD tracking — current working directory always visible in the status bar

Who This Is For

Primary Audience — AI-Native Engineers

Developers who use AI coding tools every day as a core part of their workflow. They're past the "let me try this AI thing" phase — Claude Code or Aider is open all day, on real production codebases.

Their pain: Standard terminals weren't built for this. They're duct-taping iTerm + Notes + a browser tab to manage their AI sessions.

Why terminalOS: One purpose-built workspace that gives them visibility and control over AI sessions without changing their terminal habits.

Secondary Audience — Engineering Teams Adopting AI Tooling

Team leads and senior engineers rolling out AI coding tools across their org. They care about:

• Cost predictability: Token tracking helps engineers self-regulate API usage.
• Workflow consistency: A shared tool creates a consistent AI dev experience across the team.
• Onboarding: Built-in AI launchers lower the barrier for engineers new to CLI-based AI tools.

Who This Is NOT For (Yet)

• Non-technical users — this is a power-user terminal tool.
• Teams already satisfied with Warp AI or Ghostty — though terminalOS goes deeper on AI-specific tooling.

Why terminalOS vs. Alternatives

| | terminalOS | iTerm2 / Warp | VS Code Terminal | AI IDEs (Cursor) | | ----------------------------------- | ---------- | ------------- | ---------------- | ---------------- | | Native AI tool detection | ✅ | ❌ | ❌ | Partial | | Real-time token tracking | ✅ | ❌ | ❌ | ❌ | | API error alerts | ✅ | ❌ | ❌ | ❌ | | Multi-pane AI sessions | ✅ | Manual | Manual | ❌ | | Integrated markdown editor | ✅ | ❌ | Extension | ❌ | | Markdown version history | ✅ | ❌ | ❌ | ❌ | | Built for CLI AI tools | ✅ | ❌ | ❌ | ❌ | | Works with any AI tool | ✅ | — | — | ❌ (locked in) | | Zero-install, browser-based | ✅ | ❌ | ❌ | ❌ | | 100% local — no cloud, full privacy | ✅ | ✅ | Partial | ❌ |

The key distinction: Warp and others add AI to a terminal. terminalOS is a terminal built for AI.

Installation

npx terminalos

That's it. terminalOS starts a local server on your machine and opens automatically in your browser. Everything runs locally — no cloud, no telemetry, no data sent anywhere. Your terminal sessions, files, and token usage never leave your machine.

Requirements: Node.js 18+, npm 9+

Development (hot reload)

npm run dev

Getting Started

1. Start terminalOS — run npx terminalos in your shell. It opens automatically in your browser. Then use ⌘O or the command palette to set your workspace root.
2. Launch an AI tool — press ⌘⇧C for Claude Code, ⌘⇧O for OpenCode, or type the command manually.
3. Watch the badge appear — terminalOS detects the AI process and shows a live status indicator.
4. Split your workspace — ⌘D to split right, ⌘⇧D to split below. Run your tests alongside AI.
5. Track tokens — token usage and estimated cost appear in the status bar as your AI session runs.

Keyboard Shortcuts

| Shortcut | Action | | -------- | --------------------- | | ⌘K | Open command palette | | ⌘T | New tab / workspace | | ⌘D | Split pane right | | ⌘⇧D | Split pane below | | ⌘W | Close active pane | | ⌘M | Open markdown editor | | ⌘⇧C | Launch Claude Code | | ⌘⇧O | Launch OpenCode | | ⌘O | Open folder | | ⌘S | Save file (in editor) |

On Windows/Linux, replace ⌘ with Ctrl.

Tech Stack

| Layer | Technology | | ------------------- | --------------------- | | Server runtime | Node.js 18+ | | UI framework | React 19 + TypeScript | | Build tooling | Vite 6 | | Terminal emulator | XTerm.js 5.3 | | PTY management | node-pty | | State management | Zustand 5 | | File watching | Chokidar 4 | | Markdown rendering | Marked 17 | | Syntax highlighting | Highlight.js 11 | | Virtualized lists | React Window |

Roadmap

The following are areas actively being explored based on developer feedback:

• [ ] Multi-model token display — differentiate input vs. output token costs
• [ ] Session history and replay — review past AI sessions
• [ ] Prompt scratchpad — dedicated pane for drafting and reusing prompts
• [ ] Team token budgets — per-project spend limits with alerts
• [ ] Plugin API — extend terminalOS with custom AI tool integrations

Contributing

Contributions are welcome. Please open an issue before submitting a PR for significant changes.

npm run dev    # Start development environment with hot reload

License

MIT © terminalOS

Built for the developers who run AI all day.