Describe it. Forge builds it.
Forge plans, writes, runs and fixes a real full-stack app on your own computer, with a live preview as it works.
Free to download · Version 0.1.0 · Windows 10 or 11
From idea to running app in three steps
Step 1: Describe what you want
Type it in plain words, or drop in a spec, a spreadsheet or a mockup.
Step 2: Forge builds it while you watch
It plans the work, asks only what it must, and builds in a private sandbox.
Step 3: Preview, refine, publish
See it live, ask for changes, then publish to GitHub or deploy to Vercel in one click.
Everything you need to ship a real app
Plain words first. Open “For developers” on any card for the technical detail.
Real apps, not mockups
Frontend, backend and database, all running, not a picture of an app.
+ For developers− For developers
Generates and runs the full stack in the project sandbox, with a real database behind it.
Private by design
Forge runs on your computer. Your code and keys stay with you.
+ For developers− For developers
API keys are kept in the operating system's secure store, not in project files.
Live preview
Watch the app appear as it's built, at desktop, tablet and phone sizes.
+ For developers− For developers
The preview pane runs the real dev server and switches between device widths.
It fixes itself
Forge watches the running app and repairs problems on its own. You can always go back to the last version that worked.
+ For developers− For developers
Self-healing handles known problems automatically; an AI healer takes on code errors; roll back to the last working version.
A team of agents
Specialists check the testing, the design and the security. Bigger builds get several helpers working at once.
+ For developers− For developers
Specialist agents for testing, design review and backend security review; parallel agents for larger builds.
Plan first, if you like
Read the plan and approve it before anything changes.
+ For developers− For developers
Optional plan-approval step: nothing is written until you accept the plan.
Your choice of AI
Use the AI you already trust, including models that run on your own machine.
+ For developers− For developers
Claude, OpenAI and Gemini models, local models through Ollama, or your existing Claude subscription.
Stays under budget
Set a spending limit and watch a live cost meter for each project.
+ For developers− For developers
Per-project spend limits and a live cost meter.
Undo anything
Every step is saved, so you can go back or try a different direction.
+ For developers− For developers
Checkpoints after every step; roll back or branch off at any point.
Ship it
Publish your code to GitHub and put your app online with Vercel in one click.
+ For developers− For developers
Publish to GitHub even without Git installed; deploy frontend and backend to Vercel, with automatic diagnosis when a deploy fails.
Works with your tools
Bring in an existing project and connect the services you already use.
+ For developers− For developers
Import any folder or private GitHub repository; connect Vercel, AWS, Supabase, Cloudflare, Netlify, Railway, Fly.io and Stripe.
Starters for every kind of app
Pick a starting point that fits: a website, a business tool, an interactive app or a quick prototype.
+ For developers− For developers
Websites and SaaS (Next.js), business apps (Python + PostgreSQL), interactive apps (TypeScript), flexible data (MongoDB), quick prototypes.
See it work
From one sentence to a live, published app, in three steps.
Illustrative walkthrough. The app and its content are an example.
How Forge compares
Other tools are good at what they do. Here is where Forge is different, with sources for every claim.
Mitsumi Forge
Best for: Anyone who wants a finished, running app, built on their own computer.
Emergent
Best for: People with no coding background who want a hosted service that turns a description into a live app.
OpenAI Codex
Best for: ChatGPT users and developers who want a coding agent across app, terminal, IDE and cloud.
Claude Code
Best for: Developers and teams who want an agentic coding tool across terminal, IDE, desktop and web.
T3 Code
Best for: Developers who already use agent command-line tools and want one open-source interface over them.
OpenCode
Best for: Developers who want an open-source coding agent that works with any model provider, including local models.
| Feature | Mitsumi Forge | Emergent | OpenAI Codex | Claude Code | T3 Code | OpenCode |
|---|---|---|---|---|---|---|
| Made for non-developers (no terminal needed) | Yes | Yes Aimed at non-programmers | Partly Desktop app; positioned as a coding agent | Partly Desktop app works without a terminal; positioned as a coding tool | Partly Most agents need their command-line tool set up first | Not stated |
| Desktop app with a visual interface | Yes | Not stated Web platform; no desktop app mentioned | Yes | Yes | Yes | Yes Desktop app listed as beta on its repository |
| Runs on your own computer (code stays local) | Yes Keys in the OS secure store | No Preview and publishing run on Emergent's hosting | Yes Model calls go to the provider | Yes Model calls go to the provider | Yes | Yes |
| Builds full-stack apps from a description (frontend, backend, database) | Yes | Yes Hosting, databases and APIs set up | Partly Builds and fixes code; no database or hosting set-up described | Partly Builds from plain language; no database or hosting set-up described | Not stated An interface for other coding agents | Not stated |
| Live preview while it builds | Yes Desktop, tablet and phone sizes | Yes | Not stated | Yes Browser pane in the desktop app | Not stated | Not stated |
| Isolated sandbox per project | Yes Docker sandboxes | Partly Isolation described per deploy run | Partly Isolated VM per cloud task; local sandbox | Partly Not on native Windows; cloud sessions use VMs | Not stated | Not stated |
| Database included per project | Yes | Yes | Not stated No project database described | Not stated No project database described | Not stated No project database described | Not stated No project database described |
| Plan approval before changes | Yes Optional | Yes | Partly Approval policies documented | Yes Plan mode | Partly Asks before edits in Supervised mode | Yes Plan agent |
| Parallel agents for large builds | Yes | Not stated | Yes | Yes | Not stated | Yes |
| Specialist testing and review agents | Yes Testing, design and backend security review | Partly Testing step documented; review agent not stated | Partly /review and GitHub review; no built-in reviewer agent | Partly /code-review and custom agents | Not stated | No Built-in agents don't include testing or review |
| Self-healing of the running app | Yes Automatic fixes, plus an AI healer for code errors | Not stated | Not stated | Not stated | Not stated | Not stated |
| Checkpoints and one-click rollback | Yes After every step; branch off too | Yes Database records aren't restored | Partly Revert per change; docs suggest manual Git checkpoints | Partly Doesn't track shell-command edits | Not stated | Partly /undo needs a Git repository |
| One-click deploy (frontend and backend) | Yes Vercel, with automatic diagnosis of failed deploys | Yes Publish button on its own hosting | Not stated No deploy feature described | Not stated No deploy feature described | Not stated One-click pull request; no deploy described | Not stated No deploy feature described |
| Publish to GitHub without Git installed | Yes | Partly Save to GitHub on paid plans; Git not mentioned | Not stated | Partly Cloud sessions use a GitHub App; desktop features need gh | No Docs say Git must be installed | Not stated |
| Import private GitHub repositories | Yes | Partly Can pull a repository; private not stated | Not stated | Yes | Not stated | Not stated |
| Choice of AI provider, including local models | Yes Claude, OpenAI, Gemini, Ollama | Not stated | Yes Ollama and LM Studio | Partly Cloud providers and gateways; local models not stated | Partly Choice among agents; local only if the agent supports it | Yes 75+ providers, plus local |
| Use an existing Claude subscription | Yes | Not stated | Not stated | Yes | Yes Through your own Claude Code sign-in | Partly Docs list it but note Anthropic's restrictions |
| Budget limits and cost tracking | Yes Per-project limits and live cost meter | Yes | Partly Credits shown; budget cap not stated | Yes | Not stated | Partly Spend cap on Zen models |
| Price | Free You pay your AI provider | Credit-based plans Free tier available | Included in ChatGPT plans Extra use through credits or API rates | Claude subscription Or pay-per-token API | Free Bring your own provider | Free software Model costs paid separately |
| Open source | Not stated To be confirmed | Not stated | Partly The command-line tool is; the rest isn't stated | No Anthropic terms apply | Yes MIT | Yes MIT |
Comparison based on public information as of 17 October 2026. Products change; check each vendor's site.
Which one fits you?
For each tool: when it is the better pick, and when Forge is.
Emergent
Official sitePick Emergent if
You want a hosted service where preview, database and publishing live in one place, with plan approval, checkpoints and credit budgets.
Pick Forge if
- Your code and keys stay on your computer. Emergent's preview and publishing run on its own hosting.
- You choose your AI provider, including local models. We couldn't find a provider choice stated on Emergent's site.
- Forge is free to download and you pay your AI provider directly; Emergent uses credit-based plans.
OpenAI Codex
Official sitePick OpenAI Codex if
You want a coding agent with a documented local sandbox, local-model support, parallel subagents and built-in code review.
Pick Forge if
- A complete app studio in one window: live preview, a sandbox and database per project, and deploys, not only a coding agent.
- Built for people who don't code. Codex describes itself as a coding agent.
- Self-healing of the running app, which Codex's docs don't mention.
Claude Code
Official sitePick Claude Code if
You want a general coding agent in the terminal, IDE or desktop app, with /rewind checkpoints, plan mode, parallel subagents and your Claude subscription.
Pick Forge if
- Forge includes a database per project and one-click deploys of frontend and backend. Claude Code's docs describe neither.
- Ready-made specialist agents for testing, design review and backend security review. Claude Code offers /code-review and lets you write your own agents.
- Works with Claude, OpenAI, Gemini and local models through Ollama, as well as a Claude subscription.
T3 Code
Official sitePick T3 Code if
You already use agent command-line tools and want one open-source (MIT) interface over them, with a branch per thread and one-button pull requests.
Pick Forge if
- A full builder with its own agent team, sandboxes and self-healing, rather than an interface on top of other agents.
- Publishes to GitHub even without Git installed. T3 Code's docs say Git must be installed.
- Nothing else to install first. T3 Code needs the agent tools you want to use to be set up and signed in.
OpenCode
Official sitePick OpenCode if
You are a developer who wants an open-source (MIT) agent with 75+ providers, including local models, and you're happy in the terminal.
Pick Forge if
- A complete app studio with live preview, sandboxes, a database and deploys, not only a coding agent. No terminal needed.
- Checkpoints after every step that don't depend on a Git repository. OpenCode's /undo needs one.
- Specialist testing, design and security review agents are built in.
For developers
What's under the hood, in short.
- Agent harness
- One agent loop plans, edits files, runs commands and reads the results, with specialist agents for testing, design review and backend security review.
- Docker sandboxes
- Each project runs in its own isolated sandbox with its own database. Docker Desktop is recommended on Windows.
- Context compaction
- Long sessions are compacted so the agent keeps working on big projects without losing the thread.
- Parallel tool runs
- Independent tool calls run at the same time, and bigger builds can split across several agents.
- Open model choice
- Claude, OpenAI and Gemini models, local models through Ollama, or your existing Claude subscription.
- Self-healing and checkpoints
- Known runtime problems are fixed automatically, an AI healer handles code errors, and every step is a checkpoint you can roll back to.
Free to download. You pay only your AI provider.
Forge costs nothing. You pay your AI provider directly for what you use, or use your existing Claude subscription.
Forge for Windows
Free
- Download and use Forge at no charge
- Bring your own AI key, or sign in with Claude
- Set a spending limit for each project
Questions, answered
Do I need to know how to code?
No. You describe what you want in plain words and Forge builds it. You never need a terminal. If you do code, you can read and change everything it writes.
Where does my code live?
On your own computer. Your code and your keys stay with you, and keys are kept in your operating system's secure store. Your chosen AI provider only sees what is sent to it to do the work.
Which AI models work?
Claude, OpenAI and Gemini models, local models through Ollama, or your existing Claude subscription.
What does it cost?
Forge is a free download. You pay your AI provider directly, or use your Claude subscription. You can set a spending limit per project and watch a live cost meter.
Does it work offline?
Only with a local model. Cloud AI models need an internet connection.
Is there a Mac or Linux version?
Coming soon. Leave your email on the download page and we'll let you know.
How is this different from Emergent?
Forge runs on your own computer, so your code and keys stay with you, and you choose your AI provider. Emergent describes itself as a hosted platform. See the comparison for the details and sources.
Describe your first app today.
Free to download. Runs on your own computer.