Web & App Development
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Web development services cover everything needed to put a product on the internet: custom websites, web applications, and mobile apps, plus the APIs, data, and hosting behind them. Opulon designs and builds the whole stack: a Slovakia-based studio with 180+ delivered projects, working for clients across the EU and internationally at fixed scope and fixed price.
What our web development services include
The gap between what was quoted and what the business actually needed kills more web projects than any bug in the code. We close that gap by keeping strategy, design, development, and infrastructure in one team:
- Custom websites: company sites, campaign sites, and content platforms built on modern architecture instead of page-builder templates. Fast by default, structured for search.
- Custom web application development: dashboards, customer portals, booking and filing systems, SaaS products. Front end, back end, and the API layer between them.
- Mobile apps: designed and built alongside the web platform they share data with, so the two never drift apart.
- E-commerce: stores and checkout flows, delivered through our dedicated e-commerce development practice.
- Integrations and APIs: payments, authentication, CRMs, invoicing, and the third-party tools your operations already run on.
- Hosting, deployment, and care: edge deployment, monitoring, backups, and updates after launch. A live product, not a handover ZIP.
Companies call a web development agency at different moments: a template site the business has outgrown, a product that has to exist by a specific date, an internal process held together with spreadsheets. The common thread is that the software has a job to do, and “it looks fine” is not the job.
How we take a project from brief to launch
- Scope. A discovery conversation, then a written scope: what ships, by when, at what fixed price. If part of your idea shouldn’t be built yet, we say so before you pay for it.
- Design. Structure and interface are decided before code, through our UI/UX design practice, so the build executes decisions instead of debating them.
- Build. Development in short cycles, with a staging link you can click from the first weeks. No six-week silence ending in a big reveal.
- Test. Performance budgets, accessibility checks, and QA on real devices: slow phones and weak connections included, because that is where users actually are.
- Launch and grow. Deployment, redirects, analytics, monitoring, then maintenance and a roadmap. The products that win keep shipping after launch day.
Website builder or custom development: which do you need?
The honest answer: if you need five static pages and nothing custom, a website builder is cheaper, and we will tell you so. Custom development earns its price when requirements outgrow templates: flows no builder can model, integrations with the systems you already run, hard performance targets, multilingual SEO architecture, or a product where the website is the business itself. That is the work we take on: projects where the difference between adequate and well-built shows up in revenue.
Built for Core Web Vitals and the European Accessibility Act
Performance is measurable, so we treat it as a requirement rather than a hope. Only about 45% of mobile home pages pass all three Core Web Vitals, according to the HTTP Archive Web Almanac, 2025. Most of the web fails Google’s own bar. And the bar has moved: since March 2024, the Interaction to Next Paint metric measures how a page responds when users interact with it, no longer only how fast it first loads (Google Chrome UX Report release notes, 2024). The commercial case is blunt. Deloitte research compiled in 2025 found that a 0.1-second improvement in mobile load time lifts e-commerce conversions by around 8.4%, and that a one-second delay can cut conversions by roughly 7%.
Compliance is the second non-negotiable. The European Accessibility Act has applied since 28 June 2025: websites, apps, and e-commerce services placed on the EU market must be accessible in all 27 member states, with pre-existing services given until 2030 to comply (European Commission, 2025). Enforcement is no longer theoretical: the first lawsuits under the Act were filed in France in November 2025, as reported by UsableNet. As a Slovakia-based studio building for EU and international clients, we treat accessibility as part of the build from the first component, where it costs the least.
A stack chosen for speed and for whoever maintains it after us
We build front ends with Astro and React, back ends on Node.js, and deploy to Cloudflare’s edge network, the same stack opulon.org runs on. The choice is deliberate. Node.js and React are the two most-used web technologies among the roughly 49,000 developers surveyed in the Stack Overflow Developer Survey, 2025 (48.7% and 44.7% respectively), which means the hiring pool for your product stays deep for years. You receive the repository, the infrastructure access, and the documentation: no proprietary platform, no dependency on us that you didn’t choose.
How much does custom web development cost?
Four variables move the number: how many unique pages and flows, how much custom design they need, how much logic sits in the back end, and what has to migrate from the old system. A company site and a multi-country web application are different orders of magnitude. Anyone quoting either without a written scope is guessing with your money. So we fix scope first: every engagement is priced as fixed deliverables at a fixed price, agreed before work starts. And if you are building a product, the right way to start is rarely the full vision: a scoped MVP puts the core in front of real users while the expensive decisions can still change.
If there is a website or a product on your roadmap, tell us what it needs to do. We will come back with a scope and a number, not a slide deck.
Frequently asked questions
How much does it cost to pay someone to build a website?
Cost tracks scope: the number of unique pages and flows, the depth of custom design, and how much back-end logic sits behind the interface. A five-page company site and a web application are different projects with different budgets. We scope every project to fixed deliverables at a fixed price before work starts, so you know the number before we write code.
What is the difference between a website and a web application?
A website presents content, and every visitor sees broadly the same pages. A web application does work: users sign in, create data, and change what they see: dashboards, portals, calculators, SaaS products. The distinction matters commercially, because applications need back-end architecture, testing, and ongoing maintenance that content sites don't.
Will AI replace web developers?
AI has changed how code gets written, not whether products need engineering. We use AI tooling where it genuinely speeds up the mechanical parts of a build; architecture, security, performance, and the judgment about what to build stay human. What is disappearing is the market for slow, generic websites, not the market for well-built products.
Do you build mobile apps as well as websites?
Yes. We develop mobile apps alongside the web platforms they usually connect to, so the API, data model, and design language are shared rather than duplicated. Most products we build start web-first and extend to mobile once the core is proven.
Can you rebuild my website without losing Google rankings?
Yes. Rankings survive a rebuild when migration is treated as part of the project rather than an afterthought. We map existing URLs, set redirects, preserve metadata and structured data, and watch Search Console after launch. Done properly, a rebuild is an opportunity: most sites fail Google's Core Web Vitals bar, and the new build is the moment to fix that.
Do you provide maintenance and support after launch?
Yes. Launch is the midpoint of a product's life, not the end, so we offer ongoing care: dependency and security updates, monitoring, backups, content changes, and new features as the product grows. You own the codebase and can take it in-house at any time. We document it with that in mind.