Quickstart: build your first app
In shortCreate a free account, type what your app should do into the box on Projects and press Build it. MonstarX plans the features, writes the app and shows it running in the preview, usually within a few minutes. Try it, ask for changes in the chat, then click Publish to put it online at your-app.monstarx.app.
In the next few minutes you will build a real web app — with pages, a database and sign-in — and put it on the internet. You do not need to write any code. All you need is an idea you can describe in a sentence or two.
We will build a booking site for a yoga studio as the example. Use your own idea if you have one.
Before you start
Section titled “Before you start”- A computer or a phone with a modern browser (Chrome, Safari, Edge or Firefox).
- About ten minutes.
Step 1: Create a free account
Section titled “Step 1: Create a free account”-
Go to monstarx.com and click Start building, or Sign in if you already have an account.
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Create your account with your email address, or with Google or GitHub if they are offered. The Free plan needs no credit card.
Your MonstarX account is separate from the apps you build: each app gets its own sign-ins for its own users.
Step 2: Describe your app
Section titled “Step 2: Describe your app”After you sign in you land on Projects, your home in MonstarX. The big box at the top asks What are we building next?
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Click the box and describe your app in plain words: who it is for, and what people should be able to do in it.
A booking site for my yoga studio: a weekly class timetable, a spot limit for each class, member sign-in, and a confirmation email when someone books.
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Press Build it, or press Enter. (Shift Enter starts a new line.)
Not sure what to write? Click one of the ideas under the box — Client portal, Booking site, Internal tool, AI assistant or Marketplace app — to fill it in, then change the words to fit you. When you stop typing, Auto Enhance with AI offers to turn a rough idea into a detailed request — see Auto Enhance.
Options you can leave for now
Section titled “Options you can leave for now”Under the box are a few switches. You do not need any of them for your first app:
| Option | What it does |
|---|---|
| Plan first | MonstarX asks you a few questions — who uses the app, its name, its look — before it builds. See Plan first. |
| Design first | Shows you a few finished-looking first screens; the one you pick sets the look of the whole app. See Design first. |
| Auto (the model) | Picks the best AI model for each request. See Choose a model. |
| The paperclip | Attach screenshots, mockups, documents or a spreadsheet. See Attach files. |
| Import | Bring in an app you already have — from GitHub, Lovable, a .zip or a public website. See Import an app. |
| Figma | Turn a Figma design into a working app. See Build from Figma. |
| Your agent | Send an app you built in Claude Code, Codex or Cursor to MonstarX. See Start from your coding agent. |
Step 3: Watch it being built
Section titled “Step 3: Watch it being built”MonstarX creates your project and opens it. From here on the work happens on MonstarX’s cloud, not in your browser.
Here is what you see:
- Your request at the top of the chat, and under it what MonstarX is doing right now — “Reasoning…”, “Planning the features…”, “Writing code…”.
- A plan of features — a short checklist of what it will build, such as “Weekly class timetable” and “Member sign-in and sign-up”. It ticks each one off as it goes. The Features bar at the top of the chat shows how many are built.
- The preview on the right. Until there is something to show, a card says Building your app… with a timer, above Monstar Run, a small game you can play while you wait (press Space to jump).
A first build usually takes a few minutes. Bigger apps take longer.
Step 4: Try your app
Section titled “Step 4: Try your app”When the build is done, your app appears in the preview. It is the real app, running: click around it, fill in its forms and sign up, as a visitor would.
In the chat, look for:
- Demo account ready — an email and password MonstarX made so you can sign in to your app straight away (when your app has sign-in). Copy them with the buttons beside them.
- Everything on the plan is built — a short summary of what the app does now.
- Ideas for what’s next — suggestions for the next features. Click Add to put one on the plan (or Add all), then Build it. They are optional.
MonstarX also gives the project a short name and description based on what it built. You can change them at any time by clicking the name at the top.
Step 5: Change anything by asking
Section titled “Step 5: Change anything by asking”Keep going in the same chat. Type what should change, in plain words, and press Send.
Some good first changes:
- “Make the header dark green and use a serif font for the headings.”
- “Add a page about our teachers, with a photo and a short bio for each.”
- “When a class is full, show a Join waitlist button instead of Book.”
Would you rather point than describe? Click Edit above the preview, click the part of the page you want changed, and say what should change there. See Edit mode.
Every change is saved as a version. If you do not like a change, open Versions at the top and restore the one before. See Versions.
Step 6: Publish it
Section titled “Step 6: Publish it”When you are happy, put your app on the internet.
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Click Publish at the top right of the project.
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Click Publish site. The menu shows the progress — Preparing your site, Building your site, Putting your site online — and you can close it while it works.
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Click Visit site to open it, or Copy link to share it.
Your app is now live at its own address, made from the project’s name — like yoga-studio-booking.monstarx.app — with HTTPS. When you change the app later, click Publish and Republish to update the live site — your visitors never see a half-finished change. See Publish your app.
Want your own name, like sagebrookyoga.com? You can buy a domain in a few clicks or connect one you own.
What next?
Section titled “What next?”- Test it properly. MonstarX can test your app in real browsers and fix what fails. See QA testing.
- Look at your data. The Admin tab shows who signed up and every booking, in plain forms. See The Admin panel.
- Get better results from your requests. See Prompting tips.
- Learn your way around. See the Tour of the workspace.
Frequently asked questions
Section titled “Frequently asked questions”How long does the first build take?
Usually a few minutes. A big app with many features takes longer. You can close the tab while it builds: the build keeps running on MonstarX, and you can get a notification when it is done.
What should I write in my first request?
Who the app is for and what people should be able to do in it, in one to three sentences. You can add everything else later. See Prompting tips.
Does building my first app cost anything?
Not on the Free plan: every request uses some of your plan's usage, and the Free plan has enough to build and publish a small app. See Usage and limits.
Can I stop a build?
Yes. Click the red Stop button in the prompt box. What was built so far is kept, and you can carry on with a new request.
Is my app public as soon as it is built?
No. Until you click Publish, it is not on the internet at its own address: only you, the people you share the project with, and anyone you send the preview's link to can see it.
Something went wrong. What do I do?
Tell MonstarX in the chat what you see, or restore an earlier version from Versions. See Troubleshooting.