v0 Built Your Frontend. Now You Need a Backend.

Your demo looks incredible.

Pixel-perfect cards. Smooth transitions. A dashboard that feels like it belongs to a Series B company. You pulled it together in an afternoon with v0, and every person you’ve shown it to has said the same thing: “This looks real.”

It does look real. That’s the problem.

Click any button and nothing happens. Submit a form and it goes nowhere. Pull up that analytics chart and the data is hardcoded. Your beautiful frontend is a movie set — all facade, no plumbing.

This isn’t a knock on v0. It’s genuinely impressive at what it does. But what it does is generate UI. React components. Visual layouts. The pixels on the screen. It doesn’t generate the systems those pixels need to connect to in order to actually work.

You don’t have an app. You have a very convincing screenshot that happens to run in a browser.

The good news: that frontend is a real asset. It’s not wasted work. But between where you are now and a product someone can actually use, there’s an entire backend that needs to exist. Data persistence. Authentication. Business logic. API endpoints. Infrastructure. The invisible machinery that makes software actually do things.

If you’re staring at a gorgeous v0 frontend wondering why it feels hollow, you’re not alone. And the path forward is more straightforward than you think.

Why v0 apps feel incomplete

v0 is exceptional at what it does. It takes a prompt and generates clean, well-structured React components. The output uses modern patterns. The styling is polished. For generating UI, it’s one of the best tools available.

The disconnect happens when founders treat v0 output as an app instead of what it actually is: a starting point for the frontend layer of an app.

A web application has layers. The frontend — what users see and interact with — is one layer. Behind it sits an API layer that handles requests. Behind that sits business logic that enforces rules. Behind that sits a database that stores data. Around all of it sits infrastructure that keeps everything running.

v0 generates the first layer. The outermost shell. Everything behind it is up to you.

This isn’t a flaw. v0 is a UI generation tool, and it’s honest about that. The problem is the gap between what v0 produces and what founders think they have. When your dashboard renders beautifully and your components respond to clicks with smooth animations, it feels like you’re 80% done. The reality is closer to 20%.

The frontend is the most visible part of an application. It’s also the smallest part in terms of actual complexity. The hard work — data modeling, authentication flows, authorization rules, API design, error handling, deployment — all lives behind the screen.

We’ve seen this pattern repeatedly. A founder spends a weekend generating screens with v0. By Sunday night they have what looks like a complete product. By the following Friday they realize they can’t ship any of it because none of it connects to anything real. The screens exist in isolation, powered by mock data and placeholder logic.

If this sounds familiar, you’re experiencing the frontend illusion. And the fix starts with understanding exactly what’s missing.

What’s actually missing from your v0 app

Let’s be specific. When we audit v0-generated frontends, we consistently find the same five gaps.

No data persistence. Everything your app “shows” is either hardcoded or stored in component state. Refresh the page and it’s gone. There’s no database. No data model. The user table in your admin panel is a JSON array sitting in a TypeScript file. It looks real, but it’s a prop on a component — not a record in a database.

This matters because the entire point of most applications is to create, store, and retrieve data. Without persistence, your app is a slideshow.

No authentication backend. v0 can generate a gorgeous login form. Email field, password field, submit button, maybe even a “Forgot password?” link. But submitting that form does nothing meaningful. There’s no identity provider. No session management. No password hashing. No token generation. The form exists as UI. The system that actually verifies identity doesn’t.

Some founders wire up a quick auth solution and call it done. But authentication without proper authorization — controlling what authenticated users can actually access — is barely better than no auth at all.

No API layer. Your frontend components expect data. In a real application, they get that data by calling API endpoints. Your v0 app has no endpoints to call. Components render with mock data or hardcoded values. When you try to connect them to a real data source, you realize there’s nothing to connect to.

Building an API layer isn’t just standing up a few routes. It’s designing a contract between your frontend and backend. It’s deciding what data shapes flow in each direction. It’s handling errors, validating input, managing rate limits. It’s a real engineering effort.

No server-side logic. Business rules live on the server. “Users on the free plan can create up to 3 projects.” “Invoices can only be edited before they’re sent.” “Admins can view all records; members can only view their own.” None of this exists in your v0 app. Every rule, every validation, every piece of logic that makes your product your product — it’s all missing.

Client-side validation is a courtesy. Server-side validation is a requirement. Without it, anyone with browser dev tools can do whatever they want.

No infrastructure. Your v0 app runs on localhost or in a preview deployment. There’s no production database. No environment configuration. No CI/CD pipeline. No monitoring. No logging. When something breaks — and it will — you won’t know about it until a user tells you. If you even have users yet, because there’s no deployment strategy to get the app in front of them.

These five gaps are the difference between a frontend and a product. Closing them is the actual work of building software.

What happens when you demo a facade

We worked with a fintech startup last year that learned this the hard way.

The founders had used v0 to generate an investor-facing dashboard. It was sharp. Clean data tables, interactive charts, a sidebar with navigation between different views. They demoed it to three VC firms in a single week.

Two of them wrote checks.

Then the real timeline started. The founders had funding, a launch date they’d committed to, and approximately 40 React components that didn’t connect to anything. The “transaction history” was a hardcoded array. The “user settings” page saved to local state that disappeared on refresh. The charts pulled from a static JSON file.

They’d estimated two weeks to “hook everything up.” It took three months.

Not because they were slow. Because “hooking everything up” meant designing a data model, choosing and provisioning a database, building an API, implementing real authentication, writing business logic for transaction processing, setting up a deployment pipeline, and connecting every single component to real data sources. That’s not integration work. That’s building the product.

The v0 frontend was useful. It saved them real time on UI. But it represented maybe 15% of the total effort. They’d accidentally sold investors on a product that was 15% built.

This story isn’t unusual. It happens every time someone mistakes a frontend for a product. The gap between “looks done” and “is done” is where startups burn runway and blow deadlines.

How to build the rest

You have a v0 frontend. You need a full application. There are three realistic paths forward.

Option 1: Build from scratch behind v0 components. Set up a backend framework, design your data model, build your API, and wire everything together manually. This gives you maximum control and a codebase you fully understand. It’s also the slowest path. If you have backend engineering experience and time, it works. If you’re a solo founder with a launch date, it probably doesn’t.

Option 2: Use a Backend-as-a-Service. Supabase, Firebase, or similar platforms give you a database, auth, and basic API functionality out of the box. You can move fast. The tradeoff is flexibility. BaaS platforms work well for straightforward CRUD apps. The moment your business logic gets complex — and it will — you start fighting the platform instead of building your product. For MVPs and simple tools, this is a reasonable choice. For anything you plan to scale, the constraints will catch up with you. If you’re exploring this route, some of the same challenges apply to Bolt-generated apps and Lovable-generated apps as well.

Option 3: Build a proper backend with v0 as your starting point. This is what we recommend for anything serious. Keep the frontend — it’s good work. But treat it as a head start on the UI layer, not a foundation for the whole app. Design the backend architecture intentionally. Build it to support the product you’re actually creating, not just the screens you’ve generated.

The right choice depends on your timeline, your product complexity, and how far you plan to take this. But for most funded startups building real products, Option 3 is the answer.

How we complete v0 apps

When a founder comes to us with a v0 frontend, we don’t throw it away. We build behind it.

The UI is usually solid. v0 generates clean component structures, reasonable naming conventions, and modern React patterns. That’s real value. What’s missing is everything the UI needs to connect to.

Here’s how we approach it.

First, we audit what exists. We map every component, identify what data it expects, and catalog what interactions it supports. This gives us a clear picture of what the backend needs to provide. We’re reverse-engineering the API contract from the UI.

Then we design the data model. Every entity your app deals with — users, projects, transactions, whatever your domain requires — gets properly modeled. Relationships, constraints, indexes. We think through the data layer before writing a line of backend code. Getting this right early saves weeks later.

Next, we build the API layer. Real endpoints that serve real data. We match the data shapes your v0 components already expect wherever possible, minimizing changes to the frontend. REST or GraphQL, depending on what your product needs. Proper error handling, input validation, pagination.

We add authentication and security. Not just login forms that work, but a complete auth system. Session management. Role-based access control. Row-level security where needed. We make sure users can only see and do what they’re supposed to see and do.

Then we connect everything. Swap mock data for API calls. Replace local state with server state. Wire form submissions to real endpoints. This is where your app transforms from a facade into a product. Components that used to render static data now pull from a live database. Forms that used to go nowhere now create real records.

Finally, we set up infrastructure. Database provisioning, environment management, CI/CD, monitoring, logging. Everything your app needs to run reliably in production.

The result is a full-stack application built on top of the frontend you already have. No wasted work. No starting over. Just a complete product where there used to be a shell. We do this as part of our full-stack development work, and v0 frontends are one of the most common starting points we see.

For tips on getting more out of v0 itself, check out our guide on v0 and Vercel best practices.

Turn the facade into a product

Your v0 frontend isn’t the problem. It’s an asset. The problem is everything that doesn’t exist yet behind it.

You need a data model, an API, authentication, business logic, and infrastructure. You need the invisible 80% that turns a UI into a product people can actually use.

We’ve done this before. We know what’s missing, we know the order to build it, and we know how to keep your existing frontend intact while we do it.

Let’s talk about what goes behind your v0 app.

Have a v0 frontend that needs a backend? Variant Systems helps founders turn beautiful UI into fully functional products.