Any CLI. Instant GUI. One command.

As featured in The Register ·

Turn any command-line tool into a clean local web form — no config, no code changes to the tool.

npx instagui ffmpeg

That's it. instagui reads the tool's --help, turns it into a web form, opens your browser, and (when you click Run) executes the command locally and streams the output back — while always showing you the exact command it will run, so it teaches you the CLI instead of hiding it.

Thousands of powerful CLIs (ffmpeg, pandoc, yt-dlp, curl, imagemagick…) are unfriendly to anyone who doesn't live in a terminal — and even experts re-read man pages to recall flag syntax. Tools like Gooey require the tool's author to change their code. instagui needs nothing from the tool: it parses the tool's own --help text with AI into a structured schema and renders that as a form.

The demo tools ship with bundled schemas, so they work instantly with no API key:

npx instagui ffmpeg      # video/audio transcoding
npx instagui yt-dlp      # download media
npx instagui pandoc      # convert documents

More common tools are bundled too — curl, jq, tar, magick, and zip — and are just as keyless. For any other tool, instagui extracts the schema on first run using the Claude API (see How it stays free):

export ANTHROPIC_API_KEY=sk-ant-...    # POSIX
$env:ANTHROPIC_API_KEY="sk-ant-..."    # Windows / PowerShell
npx instagui wget

Get a key at https://console.anthropic.com. The first extraction is cached, so every launch after that is instant and free.

Fresh extraction (a tool that isn't bundled or cached) needs an AI engine, but you rarely have to pick one yourself: instagui auto-detects what you already have.

Selection order (first hit wins):

1. --engine <name> on the command line
2. INSTAGUI_ENGINE environment variable
3. default in ~/.instagui/config.json
4. auto-detect — a set API key wins; otherwise a logged-in CLI:
   1. ANTHROPIC_API_KEY → OPENAI_API_KEY → GEMINI_API_KEY → DEEPSEEK_API_KEY (first that's set)
   2. else claude → codex → gemini (first CLI found on PATH)

So if you already have a Claude/ChatGPT/Gemini API key exported, or you're logged into the claude, codex, or gemini CLI, instagui just uses it — no flags needed. A set API key always wins over a logged-in CLI, so existing key-based setups keep working exactly as before.

Run instagui --engines to see every configured engine and whether it's ready right now — for each one it says exactly why (which key is set or not, or whether the CLI is on your PATH). It never prints a key value, only its status:

$ npx instagui --engines
Available instagui AI engines (● = ready now):

  ○ anthropic  anthropic          ANTHROPIC_API_KEY: not set
  ● openai     openai-compatible  OPENAI_API_KEY: set
  ○ google     openai-compatible  GEMINI_API_KEY: not set
  ○ deepseek   openai-compatible  DEEPSEEK_API_KEY: not set
  ● ollama     openai-compatible  local endpoint (http://localhost:11434/v1) — no key needed
  ○ claude     cli                claude CLI — not found on PATH
  ● codex      cli                codex CLI — found on PATH
  ○ gemini     cli                gemini CLI — not found on PATH

So instagui never asks you to put a key in a file — you set the relevant environment variable (the one named in each row), and --engines confirms it's picked up.

Pick one explicitly with --engine <name>:

npx instagui wget --engine claude    # use the claude CLI (no API key needed, just `claude` login)
npx instagui wget --engine openai    # use the OpenAI API (needs OPENAI_API_KEY)

Built-in engine names, no config required:

To add another provider (e.g. Kimi/Moonshot, a hosted vLLM/LM Studio endpoint), change a default model, or set a default engine, create ~/.instagui/config.json:

{
  "default": "claude",
  "engines": {
    "claude":   { "kind": "cli", "binary": "claude", "model": "sonnet" },
    "anthropic":{ "kind": "anthropic", "keyEnv": "ANTHROPIC_API_KEY", "model": "claude-haiku-4-5" },
    "openai":   { "kind": "openai-compatible", "baseURL": "https://api.openai.com/v1", "keyEnv": "OPENAI_API_KEY", "model": "gpt-4o-mini" },
    "google":   { "kind": "openai-compatible", "baseURL": "https://generativelanguage.googleapis.com/v1beta/openai/", "keyEnv": "GEMINI_API_KEY", "model": "gemini-2.5-flash" },
    "ollama":   { "kind": "openai-compatible", "baseURL": "http://localhost:11434/v1", "model": "llama3.1" },
    "kimi":     { "kind": "openai-compatible", "baseURL": "https://api.moonshot.cn/v1", "keyEnv": "MOONSHOT_API_KEY", "model": "moonshot-v1-8k" }
  }
}

engines entries are merged over the built-ins (same name overrides). keyEnv names an environment variable that holds the key — instagui never reads a raw key from disk, and a config that puts a plaintext key in the file is rejected with an error pointing you back to keyEnv.

None of this applies to the bundled tools (ffmpeg, yt-dlp, pandoc, curl, jq, tar, magick, zip): they resolve from shipped schemas and need no engine at all, ready or not.

1. Capture — run <tool> --help (falling back to -h, help, then the man page), reading both stdout and stderr, under a timeout and size cap so a misbehaving tool can't hang the launch.
2. Extract — send the help text to the Claude API (claude-haiku-4-5) and get back a validated JSON schema of the tool's options (name, flag, type, description, enum values, required, grouping) plus positional arguments. Invalid output is retried once, then fails clearly.
3. Serve — render the schema as a single-page form on http://127.0.0.1, grouped, with the right control per type (checkbox / dropdown / number / text).
4. Preview — show the exact command as you edit the form, one-click copyable.
5. Run — execute the command with spawn (arguments array, never a shell string) and stream stdout/stderr live into the page until it exits.

instagui resolves a schema in this order, and only the last step costs an API call:

So the demo tools are free forever, any tool you've used once is free forever after, and you only need a working engine the first time you point instagui at a brand-new tool. A friendly message tells you exactly what to do if none is configured — you're never dropped into a stack trace.

• --refresh re-extracts and overwrites your cache entry.
• --schema ./mytool.json uses a hand-tuned schema and skips capture and the AI entirely.

instagui <tool>                 resolve <tool>'s Schema and serve the Form (auto-opens the browser)
instagui <tool> --print         resolve and print the Schema JSON instead of serving
instagui <tool> --schema <path> use a hand-supplied Schema file (no capture, no AI)
instagui <tool> --refresh       ignore cache + bundled and re-extract fresh
instagui <tool> --help-file <p> extract from a captured help-text file
<tool> --help | instagui <tool> or pipe help text on stdin

  --port <n>     preferred port for the Form server (default 5177; falls back if busy)
  --no-open      do not auto-open the browser (still prints the URL)
  --model <id>   extraction model (default: claude-haiku-4-5)
  --engine <name> AI engine: anthropic | openai | google | deepseek | ollama | claude | codex
                 | gemini | any engine in ~/.instagui/config.json. Default: auto-detect.
  --engines      list engines + whether each is ready (which key is set / CLI on PATH), then exit
  -v, --version  print the instagui version
  -h, --help     show help

The form is served on 127.0.0.1 on the remote machine, so opening a browser there is useless. When instagui detects an SSH session (SSH_CONNECTION / SSH_TTY) it skips the browser auto-open and prints a copy-ready port-forward hint after the listening line:

$ instagui ffmpeg
http://127.0.0.1:5177/
instagui: Running over SSH. On your local machine run:
  ssh -L 5177:127.0.0.1:5177 <user>@<host>
then open http://127.0.0.1:5177

Run that ssh -L command in a terminal on your local machine, then open http://127.0.0.1:5177 there — the tunnel forwards your local port to the remote form. <host> is filled in from SSH_CONNECTION when available; <user> (and an unknown host) stay as placeholders for you to edit. The forwarded port always matches the port instagui bound (pass --port <n> to pick it; it falls back to a free port if busy). Nothing about the binding changes — the server is still 127.0.0.1-only, reachable only through your own tunnel.

Plain ssh -L is fine for a quick session, but the tunnel dies with the connection. For a long-lived tunnel to a box you keep coming back to, use autossh instead:

autossh -M 0 -N -f -L 5177:127.0.0.1:5177 <user>@<host>

It re-establishes the forward automatically after a network drop, so the form stays reachable without you re-running the command each time.

instagui is a local, single-user tool. Be clear-eyed about what it does:

• It runs commands you compose. The whole point is to execute a real CLI with the arguments you set in the form. Treat the form like your own terminal — don't run something you wouldn't type.
• The exact command is always shown before you Run it. No hidden arguments; preview is generated from the same argument array that Run executes, so what you see is what runs.
• Arguments are passed as an array to spawn, never concatenated into a shell. A value containing spaces, quotes, ;, or && is passed verbatim as a single argument — there is no shell to interpret it, so form input can't inject extra commands.
• The server binds 127.0.0.1 only. It is not reachable from your network.
• State-changing requests fail closed. POST /run and POST /stop require a matching Origin header; a missing or foreign origin is rejected (CSRF protection). Exactly one run at a time, and closing the tab (dropping the stream) kills the child process — no orphans.
• Your API key is never logged, echoed, or embedded in any served page. The only data that leaves your machine is the tool's help text, sent to your selected AI engine for extraction (nowhere, for a local ollama engine). No telemetry.

Want a tool to work keyless for everyone, like the demo tools do? Bundled schemas live in schemas/ and are generated from captured --help fixtures:

1. Capture the tool's help into test/fixtures/<tool>-help.txt.
2. Add the tool to scripts/gen-bundled-schemas.ts.
3. Regenerate with your key: ANTHROPIC_API_KEY=sk-ant-... npx tsx scripts/gen-bundled-schemas.ts (a hallucination guard + golden check run before anything is written).
4. Open a PR with the fixture and the generated schemas/<tool>.json.

Each generated schema is validated so every flag appears verbatim in the source help text — no hallucinated options. See schemas/README.md for provenance details.

• Node.js ≥ 22
• An AI engine — an API key (ANTHROPIC_API_KEY, OPENAI_API_KEY, GEMINI_API_KEY, ...) or a logged-in CLI (claude, codex, gemini) — only for extracting a tool that isn't bundled or cached. See Choosing an AI engine.

Deliberately out of scope to keep it small and sharp: interactive/TUI programs (vim, top, REPLs); subcommand trees (flat tools only — git commit vs git push is v0.2); native file-picker dialogs; a hosted version, auth, telemetry, or a plugin system.

If instagui saves you time, you can sponsor development on GitHub. Starring the repo and contributing schemas helps just as much.

MIT © Omar