A web app is software you use through your browser instead of a website you just read. It runs on a server, stores data in a database, remembers who you are when you log in, and lets you do things book a room, edit a doc, check a balance rather than only showing you things. If a page lets you change something and that change is saved for next time, you're using a web app, not a website.
If you've ever wondered whether the thing you want to build is "a website" or "an app," this is the question underneath that confusion. The distinction matters because it changes what you need to build it: a database, user accounts, and real backend logic, not just pages and images.
What is a web app, exactly?
A web app (short for web application) is a program that runs inside your browser but behaves like software because it is software. Instead of installing something from an app store, you go to a URL, and the server behind that URL runs code, talks to a database, and sends back a page built specifically for you.
The core technical difference from a plain web page is state and interactivity: a web app remembers things. It knows you're logged in. It knows what you added to your cart. It knows what you changed yesterday. That requires four things working together behind the scenes:
- A frontend — what you see and click in the browser
- A backend — server-side logic that decides what happens when you click
- A database — where your data (accounts, content, orders, messages) actually lives
- Authentication — a way to know who you are across visits
A brochure website doesn't need any of that beyond hosting. A web app needs all four.
Web app vs. website: what's actually different
"Website" and "web app" both live in a browser, which is exactly why people conflate them. The real difference is whether the thing is mostly read or mostly used.
| Website | Web App | |
| Primary purpose | Deliver information | Let users perform tasks |
| Content | Mostly static, same for every visitor | Dynamic, personalized per user |
| User accounts | Usually none | Login, roles, permissions |
| Database | Rarely needed | Core requirement |
| Interaction | Read, click through, maybe fill a contact form | Create, edit, save, delete data |
| Example | A restaurant's menu page | A reservation system with a live table calendar |
| Who "owns" the content | The site owner publishes; visitors just view | Every user can create and edit their own content |
That last row is the clearest test, and it echoes how Bubble.io frames it in its own explainer on the topic: a website effectively has one user, the person who published it while a web app has many users, each doing different things with their own data.
In practice the line blurs. A blog with comments is part website, part app. An e-commerce store with accounts, carts, and order history is really a web app wearing a storefront's clothes. When in doubt, ask: does this need a database and a login to work the way I'm imagining it? If yes, you're building a web app.
Web app vs. native mobile app
This is the second axis of confusion, and it's a different question entirely, not "static vs. dynamic" but "browser vs. installed."
- A web app runs in a browser (desktop or mobile) at a URL. No app store, no install, no approval process. One codebase generally works everywhere there's a browser. It updates instantly for everyone the next time they load the page.
- A native mobile app is downloaded from the App Store or Google Play, installed on the device, and typically has to be built separately for iOS and Android. It gets deeper access to device hardware (camera, notifications, offline storage, biometrics) and users update it manually — or automatically if they've allowed that.
A Progressive Web App (PWA) sits in between: it's still a web app, but it can be "installed" to a home screen, work offline to some degree, and send push notifications, borrowing some native-app conveniences without going through an app store. Twitter and Starbucks have both shipped notable PWAs, which is a useful example if you want to see the line blur in practice.
Most founders don't actually need a native app on day one - they need something people can use immediately without a download, which is exactly what a web app is for. Native makes more sense once you specifically need offline-first behavior, deep hardware access, or app-store discovery as a growth channel.
Got an idea? Build it now!
Just start with a simple prompt. No coding required — Greta.sh turns your idea into a working app in minutes.
Real examples of web apps, by category
Web apps aren't one type of product, they're a delivery mechanism used across almost every category:
- Productivity: Gmail, Google Docs, Notion
- Social/media: Instagram (in-browser), Medium, Twitter/X
- Commerce: Amazon, Shopify storefronts, Airbnb
- Finance: Online banking portals, budgeting tools
- Creative tools: Canva, Figma
- Internal business tools: CRMs, admin dashboards, booking systems, internal ticketing tools
Notice the pattern: every one of these lets a logged-in user create, store, or manipulate their own data, and that data persists the next time they come back. That's the thread connecting all of them, regardless of industry.
How this connects to building your own
If your idea involves user accounts, saved data, or anything that behaves differently for different people, you're not really scoping "a website", you're scoping a web app, and that means you need a real backend and database from day one, not just pages.
This is exactly where most non-technical founders get stuck: they can imagine the screens, but the backend, database schema, and authentication are the part that used to require hiring a developer or learning to code. That's the layer that turns a mockup into a working product, see greta.sh's guide on what backend, database, and auth actually mean for non-technical founders for a deeper walkthrough of that layer specifically.
It's also worth scoping what you're building before you build it — our guide to what an MVP actually is covers how to decide which features of your web app need to exist on day one versus later.
How Greta.sh fits in
Greta.sh is a vibe-coding platform: you describe what you want in plain English, and it builds a real, working web app - frontend, backend, database, and authentication included, not a clickable mockup with no logic behind it. Given the distinctions above, that matters: a lot of no-code and AI website builders stop at the "website" layer — a nice-looking frontend with no persistent data or real user accounts underneath.
greta.sh is built for the other side of that line. If your idea needs logins, saved user data, or anything dynamic per-user — the actual definition of a web app, greta.sh generates the backend logic and database structure alongside the interface, so what you end up with is a functioning application, not a mockup pretending to be one. If you're new to this way of building, our complete guide to vibe coding and our beginner's walkthrough of building your first full-stack app with no code are good next stops.
Got an idea? Build it now!
Just start with a simple prompt. No coding required — Greta.sh turns your idea into a working app in minutes.
Frequently asked questions
Is Instagram a website or a web app?
Both, depending on how you access it - but functionally it's a web app. The browser version at instagram.com requires a login, stores your posts and messages in a database, and shows every user a personalized feed. That interactivity and per-user data is what makes it a web app rather than a static website, even though it also has native iOS and Android apps.
Do I need to know how to code to build a web app?
Not anymore, in most cases. Platforms like greta.sh let you describe the app you want in plain English and generate the frontend, backend, database, and authentication for you. You'll still benefit from understanding the concepts in this article — what a database is for, what authentication does but writing the code yourself is no longer a hard requirement.
What's the difference between a web app and a PWA?
A Progressive Web App (PWA) is a specific type of web app built with extra capabilities, it can be added to a phone's home screen, work partially offline, and send push notifications, mimicking some native-app behavior while still running through the browser and a single shared codebase. Every PWA is a web app; not every web app is built as a PWA.
Can a website turn into a web app over time?
Yes, and it happens constantly. A site that starts as static pages often adds accounts, a dashboard, or saved user data as the product grows, at that point it has functionally become a web app, even if "website" is still what people call it out of habit. E-commerce stores are a common example: they usually start as a catalog and become a full web app once accounts, carts, and order history are added.
