Build real apps by describing what you want. No coding experience required.
SynthOS is a local AI-powered environment where you create fully functional applications — tools, games, dashboards, utilities — just by chatting. Describe what you need, refine it conversationally, and watch it appear in real time. Every app is a living page that you can save, share, and keep evolving.
Most "no-code" tools give you templates and drag-and-drop. SynthOS gives you a conversation. Tell it what you want in plain English and it builds it — HTML, CSS, JavaScript — all running live in your browser. You don't need to understand the code. But if you're curious, it's all right there, teaching you as you go.
- Zero programming knowledge needed — just describe what you want
- Unlimited flexibility — if you can imagine it, SynthOS can build it
- Learn by doing — every app you create is real, inspectable code
- Runs locally — your data and API keys never leave your machine
- Iterative refinement — keep chatting to tweak, extend, and polish
Anything that runs in a browser. Here are a few examples:
Build JSON formatters, unit converters, note-taking apps, task managers — any productivity tool you can describe.
From arcade shooters to text adventures — SynthOS ships with Neon Asteroids (a synthwave space shooter) and Oregon Trail (complete with an AI trail guide named Dusty).
Interactive charts, maps, and dashboards powered by D3.js. Describe the data you want to see and SynthOS builds the visualization.
Create rich learning experiences with built-in AI. Solar Explorer lets you click through a 3D-style solar system to learn about planets and orbital mechanics. Oregon Trail teaches frontier history through an AI guide that answers kids' questions at every stop. Western Cities 1850 pairs an interactive map with an AI historian at each location.
Your apps are saved as HTML pages that run within SynthOS. Share them with anyone else running SynthOS, or keep building on them later.
You'll need Node.js v20 or later.
npm install --global synthos
synthos startThis starts the SynthOS server at http://localhost:4242. Keep the terminal open while you work.
On your first launch, SynthOS walks you through a guided setup experience. It will help you configure your AI model, enter your API key, and learn the basics of building with SynthOS. No reading docs, no guesswork — you'll be creating your first app within minutes.
| Provider | Recommended Model | Get an API Key |
|---|---|---|
| Anthropic | Claude Opus | platform.claude.com |
| OpenAI | GPT-5.2 | platform.openai.com |
| Fireworks AI | GLM-5 | fireworks.ai |
Don't let "API key" scare you. Signing up for a developer account is just like signing up for any other online service. Create an account, generate a key, and paste it in. Many providers, like Anthropic, offer free credits to new developers — just start with those. Familiarize yourself with your provider's dashboard and keep an eye on your spending for the first few weeks.
Type what you want to create. That's it.
Use the controls above the chat box to save your app, reset the viewport, or browse your pages gallery.
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Claude Opus is recommended for the best experience overall. It produces the highest quality apps right out of the box.
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Using GPT-5.2 or GLM-5? Start with Brainstorming Mode. Click the brainstorm icon in the chat input to open an AI-powered ideation assistant that helps you explore and refine your idea before building. It generates a clean, optimized build prompt that gets dramatically better results from any model. This is especially useful with non-Opus models where prompt quality makes a bigger difference.
- Save often, reset freely. Save your app whenever you hit a version you like. Use Reset to return to your last save point and take things in a different direction. Think of it like checkpoints — experiment boldly knowing you can always go back.
You describe what you want
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AI writes the code
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App appears instantly
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You refine with chat
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Save & reuse
Every app is a self-contained HTML page. Behind the scenes, SynthOS sends your conversation and the current page state to your chosen LLM, which returns precise, surgical edits — not a full rewrite. The page updates in place — no reloads, no lost state.
SynthOS ships with starter templates so you don't have to start from scratch:
| Template | Best For |
|---|---|
| Application | Tools, utilities, single-pane apps |
| Two-Panel Page | Side-by-side layouts with a draggable splitter |
| Sidebar Page | Content with navigation or controls on the side |
| US Map | Interactive D3.js map visualization as a starting point |
Plus ready-to-use apps like My Notes (a full note-taking app with rich text editing), Neon Asteroids, and Solar Explorer — all built entirely within SynthOS.
Everything SynthOS creates lives in a .synthos folder wherever you started the server. Apps are plain HTML files you can:
- Open directly in any browser
- Copy to another machine
- Edit by hand if you want to
- Delete when you're done
SynthOS ships with dark and light themes out of the box:
- Nebula Dusk — a synthwave dark theme with glowing purple and magenta accents
- Nebula Dawn — a soft pastel light theme with the same color palette
Switch themes in Settings and every page adapts automatically.
Your apps can save and retrieve data locally — no database setup needed. Just call synthos.data.save("tasks", {title: "Buy milk"}) and it works. Build todo lists, note-taking apps, inventory trackers, and more.
Apps can make their own AI calls using synthos.generate.completion(). This is how Oregon Trail's "Dusty" guide and Western Cities' AI historian work — your apps can talk back to users intelligently.
Create shell scripts that your apps can invoke. Start builds, run Git commands, call APIs — extend SynthOS to automate anything on your machine.
Test and explore all of SynthOS's built-in APIs interactively from the APIs system page.
Connect your apps to real-world APIs without writing any authentication code. SynthOS handles credentials and proxies requests automatically.
Search & News — Brave Search, NewsAPI, RSS2JSON Developer Tools — GitHub, Jira Social Media — Instagram (full OAuth2) Databases — Airtable, Notion Communication — Twilio, SendGrid, Resend, ElevenLabs Maps & Weather — Mapbox, OpenWeatherMap Media — Unsplash, Pexels, Imgur, Giphy, Cloudinary, Stability AI Finance — Alpha Vantage, Open Exchange Rates Knowledge — NASA, Wolfram Alpha, YouTube Data, Hugging Face, DeepL Food — Spoonacular
Configure a connector in Settings, and the AI automatically knows how to use it when building your apps.
Integrate external AI agents into your apps. SynthOS supports two protocols:
- A2A (Agent-to-Agent) — standard HTTP-based agent communication with streaming support
- OpenClaw — WebSocket-based protocol with session management, chat history, and SSH tunnel support for secure remote agents
Your apps can send messages to agents, stream responses in real time, and maintain conversation history — all through synthos.agents.*.
SynthOS isn't just a tool — it's a bridge. You never need to look at the code, but the skills you build while using SynthOS are real programming skills:
- Break problems down — you'll learn to describe what you want in smaller, concrete pieces
- Think in components — headers, sidebars, buttons, data — you'll start seeing how apps are assembled
- Iterate and refine — building through conversation teaches you the same feedback loop every developer uses
- Debug by describing — when something isn't right, you'll get better at pinpointing what to change
- Build confidence — every app you ship is proof that you can create real software
You don't have to become a programmer. But if you want to, SynthOS meets you where you are.
This is an open-source project. Contributions are welcome.
The repo includes a SHARED-MEMORIES.md that gives AI coding assistants (like Claude Code) full project context. If you're contributing with Claude Code:
- Clone the repo
- Ask Claude: "Initialize my personal MEMORY.md file using SHARED-MEMORIES.md"
- Start building
MIT
Ready to build something?
npm install --global synthos
synthos start