Get In Touch
Ground Floor,Kitab Mahal 192,
D. N. Road, Azad Maidan,
Fort, Mumbai, Maharashtra India
Ph: +91.981.993.3339
Work Inquiries
info@catalystmi.com
+91.22.460.16261

Web Application Development

Custom web apps for SaaS, customer platforms and internal tools

Building for the Modern Web

We architect the platform before we write a line of frontend code

Wireframes and UI/UX first, scope and data points documented, then a build that separates the frontend cleanly from the API behind it.

We design the interface, then engineer the platform underneath it. Every screen is wireframed, the user experience is thought through, and scope and data points are documented before we build. The result is a custom web application built on a multi-tier architecture – a precise frontend consuming secure APIs – not a template stretched to fit.

Design and Scope -   Modern Apps for the  Modern  Web
Build,   where the  frontend and the  APIs come together
Launch and Scale,  bringing  it  all  together

Design and Scope -
Modern Apps for the
Modern
Web

We wireframe the screens, design the UI and UX, and document the full scope and data points. Clients see exactly what the platform does before we build it, and UI/UX is where we do our sharpest work.

Build,
where the frontend
and the
APIs come together

We code the frontend precisely to the design, build APIs to an OpenAPI spec with web SDKs, integrate third parties securely, and drive content through our Admin Portal.

Launch and Scale,
bringing it
all
together

QA testing, performance tuning, responsiveness checks and security scans run before anything ships. Then we deploy through CI/CD to a cloud setup that scales.

Design and Scope -   Modern Apps for the  Modern  Web

Design and Scope -
Modern Apps for the
Modern
Web

We wireframe the screens, design the UI and UX, and document the full scope and data points. Clients see exactly what the platform does before we build it, and UI/UX is where we do our sharpest work.
Build,   where the  frontend and the  APIs come together

Build,
where the frontend
and the
APIs come together

We code the frontend precisely to the design, build APIs to an OpenAPI spec with web SDKs, integrate third parties securely, and drive content through our Admin Portal.

Launch and Scale,  bringing  it  all  together

Launch and Scale,
bringing it
all
together

QA testing, performance tuning, responsiveness checks and security scans run before anything ships. Then we deploy through CI/CD to a cloud setup that scales.

Why go Custom?

Because API-first, security, processes & UX matter

We build web applications the way a product team would, not the way a template shop does. The architecture is API-first and multi-tier, so the frontend, the APIs and the data layer are separated cleanly and each can scale or change without breaking the others. APIs are built to an OpenAPI spec with web SDKs, which makes integrations predictable and the platform easier to extend later. Security is designed in, not bolted on afterward.Our approach to mobile app development builds in React Native because it puts iOS and Android on a single codebase without the wrapped-website feel that users notice in a second. The performance reads as native. Where a feature demands genuine native code, we write it. That is the honest version of cross-platform – one team, one vision, one build that behaves like two.

Documentation is a first-class deliverable here, not a nicety. Every build ships with functional and technical documentation, so your team can operate, extend and hand over the platform without reverse-engineering it. Our processes are documented for the same reason. And the interface itself gets real attention – the UI and UX are where a lot of web apps fall down, and where we spend the effort to make the platform genuinely usable. This is Software Product Development discipline applied to the web, drawn from web application development experience in India and Europe across BFSI, finance, consulting and sports and entertainment. Delivery is AI-augmented across planning, coding, testing and documentation, with every output human validated before it ships, and we hold an 80%+ test coverage baseline on the code we write.

What We Offer

We cover the full build - design, engineering, integration, deployment and long-term care.

Mobile app strategy and platform consulting session

Wireframing & UX Design

Screens wireframed, flows designed, scope set up front

React Native and Expo mobile app development

API & Backend Development

OpenAPI-spec APIs and web SDKs on a multi-tier backend

Mobile app QA and security testing

Secure Integrations

Third-party services integrated securely end to end

Mobile app maintenance support and over-the-air updates

Cloud Deployment & CI/CD

CI/CD pipelines deploying to a cloud setup that scales

Mobile app UI and UX design in Figma

Frontend Engineering

Frontend coded precisely to the signed-off design

Scalable mobile app backend and API development

Admin Portal & CMS

Content and platform run through a custom Admin Portal

Mobile app maintenance support and over-the-air updates

QA, Performance, Security

QA, performance tuning and security scans before launch

Mobile app maintenance support and over-the-air updates

Maintenance & Support

AMC options for long-term platform care after launch

What Sets Us Apart

Every choice on the build serves the platform your users touch and your team runs.We build apps that hold up under real money, real users, and real store review.

API-first, multi-tier architecture that scales

Security designed into the platform, not bolted on

UI and UX we genuinely sweat over

Responsive across every screen it runs on

Third-party integrations built to hold up in production

Functional and technical documentation with every build

80%+ test coverage baseline on the code we write
AI-augmented delivery, every output human validated

Statistics are a great icebreaker... here are a few opening numbers

0
App of the Day wins
0 m
App Downloads
0
Technologies
0
Pipelines Deployed
How we work

Some of the Recent Work crafted by our team

Jebel Ali Racecourse Website

CMI, Web & Mobile Application

Jebel Ali Racecourse Mobile App

CMI, Web & Mobile Application

Elevate Golf Mobile App

CMI, Web & Mobile Application

Kyoho.io Marketing Website

CMI, Web & Mobile Application

Kyoho.io Platform

CMI, Web & Mobile Application

JARC Web App

CMI, Web & Mobile Application

Our Engagement Models

How We Work Together

Choose the model that fits your project stage and how you want to work
Fixed bid engagement model for mobile app projects

Fixed Bid

Best when scope and timeline are defined upfront
Dedicated team engagement model for ongoing app development

Dedicated Team / RaaS

Engineers embedded with your team for the long run
Annual maintenance contract for mobile app support

Annual Maintenance Contract

Ongoing support and updates once the app is live

Frequently Asked Questions

Questions buyers ask

Straight answers on how we build mobile apps, what they cost to plan for, and how we decide between native and cross-platform.

What's the difference between a web app and a website?

A web application does work for the user, while a website presents information. A web app has logic, user accounts, changing data, and features people interact with - dashboards, portals, SaaS products, internal tools. We build the interactive, engineered kind, on a multi-tier architecture rather than a template. If your product needs users to do things, not just read, it is a web application.

What tech stack do you build web applications on?

We build frontends in Next.js and React with shadcn/ui, and back them with FastAPI, PostgreSQL and Redis, hosted on AWS and DigitalOcean. The frontend talks to APIs built to an OpenAPI spec, hosted on secure API gateways. We pick the parts to fit the platform rather than forcing every project through the same stack, and we stay current rather than married to one way of building.

How do you keep a web application secure?

Security is designed into the architecture from the start, not added at the end. The multi-tier separation keeps the data layer behind the API, integrations are built secure, and every build runs through security scans before it ships. We apply the same discipline we use on BFSI and finance platforms, where security is not optional. Documentation records how the platform is secured.

What is API-first architecture and why does it matter?

It means the frontend, the APIs and the data layer are separate, and the APIs are designed first to a clear OpenAPI spec. Each layer can scale or change without breaking the others, integrations become predictable, and the platform is far easier to extend later. It is the difference between a web app you can grow and one you have to rebuild. A web frontend and a mobile app can share one backend.

Do you build the admin portal and CMS too?

Yes. We build the admin layer on Nucleus, our ground-up admin portal where the features and mechanics of a modern back office are already built - so clients do not pay to build that groundwork from scratch. You pay only for the modules and functionality we build specifically for you. It ships with functional and technical documentation, so your team can run the platform without guesswork.

Do you provide documentation and post-launch support?

Yes, both. Every build ships with functional and technical documentation as a first-class deliverable, so your team can operate and extend the platform. After launch, AMC options cover fixes and updates, and our Dedicated Teams (RaaS) model gives you ongoing engineering capacity embedded with your team. We work toward long partnerships, with average client tenure of 3-4+ years.

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Ready to Build the Future of Your Product?