Application frontends that feel clear, fast, and easy to use.

Application frontends, not marketing sites

Front-end development services cover the engineering of product interfaces, dashboards, customer portals, admin panels, AI assistant UIs, onboarding flows, and the design systems that keep them consistent. That is the work on this page. If what you need is a marketing site, that is a different discipline with different goals, and it lives with our website design team.

The distinction matters because application UI fails differently than a content page. A product screen has state: loading, empty, error, partial, success. It has users with roles and permissions. It has data arriving late, in the wrong shape, or not at all. Most "the app feels slow and confusing" complaints trace back to interfaces built as if none of that would happen.

Entropy & Co. builds the interfaces your customers and teams actually touch, in React and Next.js with TypeScript on every project. We focus on speed, clarity, responsiveness, accessibility, and the small details that make users trust what they see.

What we build

• React and Next.js interfaces. App Router, server components where they actually reduce client work, TypeScript in strict mode, and a folder structure the next engineer can navigate without a tour guide.

• AI assistant and chatbot UIs. Streaming responses, visible tool-call states, conversation history, and honest failure messages, the difference between an AI feature users adopt and one they quietly abandon.

• Internal dashboards. Tailwind, shadcn/ui, TanStack Table and Query, and Recharts, data-dense screens that load fast and stay readable.

• Admin panels. Role-aware views, confirmations on destructive actions, and audit-friendly behavior.

• Customer portals. Authentication with Clerk or Auth0, Stripe billing views, document upload and status tracking.

• Form flows and onboarding screens. React Hook Form and Zod validation, inline errors users can actually recover from, and progress that survives a page refresh.

• Design-system components. Tokenized, documented in Storybook, and versioned so product teams stop rebuilding the same button.

• Responsive UI implementation. Figma to production with fidelity you can check side by side.

• Frontend performance improvements. Bundle audits, code splitting, image and font discipline, Core Web Vitals remediation.

What good frontend work includes

Good frontend work is mostly invisible: the screen loads fast, nothing jumps, and the error message tells you what to do next. This is the checklist we hold every build to:

• Clean, reusable component structure

• Mobile-first responsive layouts

• Accessibility to WCAG 2.2 AA targets, keyboard navigation, focus management, contrast, screen-reader labels

• Core Web Vitals treated as an engineering budget: LCP under 2.5s, INP under 200ms, CLS under 0.1, here is why those numbers decide whether visitors become leads

• Form validation and error states

• Loading, empty, and success states, the three screens most teams never design

• Analytics-ready events (GA4, PostHog) wired in at build time, not retrofitted

• Cross-browser and cross-device QA, automated with Playwright

• Design-to-development fidelity

• Code the next engineer can maintain without a decoder ring

How we work

1. Clarify the user path. We define what the screen needs to help someone do before anyone opens an editor. A few days of focused working sessions, not weeks of discovery theater.

2. Translate design into structure. Reusable components, responsive layouts, and explicit UI states for loading, error, and empty.

3. Connect the frontend to real data. APIs, forms, authentication, AI endpoints, or CMS content, with the failure cases handled, because production data is never as polite as mock data.

4. Test across devices. Mobile, desktop, slow networks, keyboard-only navigation, and the edge states that only appear when a real user does something unexpected.

5. Hand off cleanly. Documentation on what matters: component conventions, state patterns, and how to add a screen without breaking three others.

A component library typically takes one to two weeks. A dashboard or portal MVP usually lands in three to six weeks, depending on integration count. You get a real date after scoping, not a shrug.

The dashboards and portals we build often sit on top of systems we have already automated, lead intake, CRM syncing, client onboarding, order fulfillment, legal operations. When one team designs the interface and the data layer together, the UI stops being a wrapper around a workflow nobody mapped. If the data layer itself is the bottleneck, start with backend development, or take both as one full-stack engagement.

Ready to scope the work? Build a frontend.

Why hire a frontend development company instead of a freelancer

A frontend development company earns its fee when the interface has to outlive any single engineer: multiple screens, a design system, real QA, and a handoff your team can maintain. For a one-screen prototype, a good freelancer is the right call, and we will tell you that in the first conversation.

The cost math deserves honesty. A mid-level frontend engineer in the US runs roughly $120K–$160K a year before benefits, and directory-listed agency rates span roughly $25–$50 per hour for offshore teams to $100–$200 for senior US engineers. We broke down the in-house developer vs agency cost math, the short version is that the right answer depends on whether the work is a project or a permanent function.

What a company gives you that a solo contractor structurally cannot: a second senior engineer reviewing every pull request, continuity when someone leaves, QA that is not the author grading their own homework, and documentation written for the people who come after.

Rescue work: AI-generated and legacy frontends

If you have an app that was built fast with AI tools and now stalls before production, you are in the most common frontend situation of 2026, and it is usually fixable without a rewrite. The failure pattern is consistent: no error boundaries, no loading states, secrets in client code, multi-megabyte bundles, and zero tests. Demo quality, not production quality.

We take these projects on regularly. The approach is staged: stabilize what users touch, add types and tests around the hot paths, then refactor, in that order, because a rewrite resets the clock and tends to reintroduce the same gaps. We published the exact production checklist we run on vibe-coded apps and an honest look at where AI-generated code accumulates technical debt. AI is in our build loop too, the difference is senior review, a test suite, and a budget for the parts of the job an autocomplete cannot see.

What front-end development costs

Market rates first, since almost nobody publishes them: agency rates listed on directories like Clutch run roughly $25–$50 per hour offshore and $100–$200 per hour for senior US engineers, and fixed-scope interface projects span from a few thousand dollars for a component library to six figures for a multi-portal product build. What moves the price on any quote, ours included:

• Scope: number of screens, roles, and UI states

• Design readiness: finished Figma files versus design work still to do

• Integration count: APIs, auth, billing, AI endpoints

• Accessibility and compliance requirements

• Browser and device matrix

• Performance budgets and existing technical debt

We quote fixed scopes after a working session, and the quote names what is explicitly out of scope, the line item most surprises hide behind.

FAQ

Can you work from Figma?

Yes. We can build from existing designs or help refine the UX before development. If the files are incomplete, we fill the gaps, states, breakpoints, edge cases, before they become production surprises.

Can you improve an existing frontend instead of rebuilding it?

Yes. We can improve speed, responsiveness, usability, conversion flow, and component structure. Most engagements start with an audit that tells you what is worth fixing and what is fine as is.

Do you handle backend too?

Yes. If the project needs APIs, authentication, databases, or integrations, Entropy can support the full stack, see backend development and full-stack development.

What stack do you default to?

React, Next.js, TypeScript, Tailwind, and shadcn/ui, deployed on Vercel or your own infrastructure. If you already run Vue, Svelte, or Angular, we maintain and extend rather than push a migration you do not need.

How long does a frontend project take?

A component library: one to two weeks. A dashboard or portal MVP: three to six weeks. A rescue engagement depends on the audit, which is where we always start. You get dates after scoping, and we hold them.

If the interface is slowing users down

We can help make it faster, clearer, and easier to trust. Tell us what your users touch and where it hurts, and we will come back with a scoped plan, an honest timeline, and the first thing worth fixing.

Build a frontend