Web apps engineered for outcomes. Conversion. Speed. Real usage.
Web platforms, apps, and digital products built to convert — and built to scale with you.
- Fixed scope, fixed price — no scope creep, no surprise invoices
- Performance built into the spec, not patched in after launch
- AI-assisted build and QA — fewer bugs, more product
- Future-ready architecture that scales as you grow
Request a free build review
30 minutes with a senior product engineer. We'll pressure-test your scope, surface the riskiest unknowns, and sketch a delivery path — conversation, not a sales pitch.
Trusted by founders & product teams scaling their next version.
Product, design, engineering, QA, and DevOps — delivering as one squad.
The roadmap is full. The release isn't shipping.
Estimates kept slipping.
Two vendors quoted twelve weeks. Six months later you're still hunting bugs and the launch keeps moving. Fixed scope and fixed price exist for a reason — and most agencies avoid them.
Design and engineering aren't joined up.
Beautiful Figma files, but the build doesn't match. Every round between designers and devs takes weeks, and what shipped looks nothing like what was sold.
Performance is an afterthought.
The product feels slow on real devices. Core Web Vitals are red. By the time anyone notices, half the launch budget is gone and traffic is dropping off before the first conversion.
AI feels mandatory but messy.
You know AI features need to land in the product, but no one on the team owns the integration, eval, or cost path.
Driven by user interactions, built for measurable performance.
Product, design, engineering, QA, and DevOps managed as a single workflow — so you ship in weeks not quarters, and the team that designed it is the team that built it.
Custom website & web application development
Custom-built sites and scalable web applications, designed to reflect your brand, engage users, and convert visitors into customers. Fast, responsive, optimised for every device, and built to handle complex business logic without breaking under load.
iOS, Android & cross-platform apps
Native iOS and Android applications where performance matters — plus cross-platform builds in React Native and Flutter when launch speed and a single codebase matter more. The right approach for your product, not a default stack.
eCommerce & CMS development
Online stores designed to reduce friction, build trust, and convert across devices — built on Shopify, WooCommerce, or custom stacks. CMS implementation across WordPress, Webflow, Sanity, or custom platforms so your team can ship content without engineering bottlenecks.
Portals, dashboards, APIs & integrations
Customer portals, admin dashboards, and internal tools that simplify operations and surface the data your team actually uses. Robust APIs and integrations connecting your stack to payment systems, CRMs, and third-party services without brittle middleware.
Progressive Web Apps & performance
Web applications that deliver app-like speed and functionality directly through the browser — no install required. Performance optimisation and technical audits to improve Core Web Vitals, load time, and the technical health of products already live.
Maintenance, support & continuous development
Ongoing updates, monitoring, and feature enhancements after launch — so the product keeps improving instead of slowly decaying. Available as a retainer or as a clean handover with documentation if you want to manage internally.
Engineered to perform. Built to scale with your business.
Share of projects delivered on or before the agreed deadline over the last five years.
Average improvement in user engagement after rebuilding a legacy digital product with a performance-focused architecture.
From funded startups to global enterprises, across B2B SaaS, consumer apps, ecommerce, fintech, healthtech, and AI — since 2019.
From first review to a product that ships on time.
Free 30-min build review
We walk through your scope, current state, and timeline. You leave with a written read of the riskiest assumptions and a realistic delivery path — written, not pitched.
Discovery & fixed-scope plan
1–2 weeks. Senior product + design pin the scope, user journeys, technical architecture, and milestone plan. You sign off on a fixed scope and a clear delivery plan before code is written.
Design & build in parallel
Design system, prototype, and engineering kick off together. AI-assisted code review and automated tests run inside the build, not bolted on. Weekly demos in staging — what you see is what ships.
Launch, monitor & keep building
App Store / Play Store submission, web go-live, performance monitoring with Sentry, and on-call coverage. Then a clean handover or an ongoing squad — your call.
We'd burned six months and two agencies before Avantus. They scoped the rebuild in a week, shipped our iOS, Android, and web app inside the agreed timeline, and the engineers are still the ones answering our Slack a year later. Best money we've spent.
Request a free
build review.
30 minutes with a senior product engineer. You leave with a written read of your scope, the riskiest unknowns, and a realistic delivery path — whether or not you decide to work with us.
- Pressure-tested scope across web, iOS, Android, and AI
- Risks & unknowns surfaced before they cost you the launch
- Realistic delivery path written up within 48 hours
- Conversation-led, never a hard pitch
Tell us what you're building
A few short questions. We'll be in touch within one business day to set up your review.