Web App Development Firm: Website & Web Application Development Services

Updated September 2026 · Written and maintained by the Progression Agency strategy team

A web application is software people use in a browser — a client portal, a booking system, an internal dashboard, a SaaS platform. Progression Agency is a web app development company that designs and builds custom web applications, progressive web apps and the APIs behind them for businesses across the United States and worldwide. This page covers what we build, how we build it, which technologies we use and what web application development typically costs.

What is web application development?

Web application development is the process of designing, building, deploying and maintaining interactive software that runs in a web browser. Unlike a brochure website, a web app has user accounts, stores and processes data, and lets people complete tasks — placing orders, managing projects, booking appointments, analyzing reports.

Because it runs in the browser, a web app works across desktop, tablet and phone without separate builds, and every user gets updates the moment they are deployed. For most businesses it is the fastest and most economical way to put custom software in front of customers and staff.

Our web application development services

Custom web app development

Bespoke applications designed around your workflows, from a focused internal tool to a full customer-facing platform.

Progressive web app development

Progressive web apps can be installed to a home screen, load quickly on poor connections and work offline to a degree, using service workers and a web app manifest as documented on web.dev. They are ideal when you want an app-like experience without app-store distribution.

SaaS platform development

Multi-tenant architecture, subscription billing, roles and permissions, onboarding and admin — see SaaS development.

API and integration development

REST and GraphQL APIs, webhooks and integrations with CRMs, ERPs, payment processors, email platforms and AI models.

Front-end development

Fast, accessible interfaces in React and Next.js, built to WCAG 2.2 AA and tuned for Core Web Vitals.

Web app modernization

Rebuilding ageing applications on current frameworks, module by module, without interrupting the people who depend on them.

Web app, progressive web app or native mobile app?

Start with a web app when reach, speed and cost matter most; choose a progressive web app when you also want home-screen installation and offline use; add native mobile apps when you need deep device hardware, background processing or app-store presence.

Many of our clients run both: a web application as the main product and a companion mobile app sharing the same backend.

How we build web applications

We design the data model and architecture first, build in two-week sprints with working releases, test automatically on every change and deploy through a CI/CD pipeline into your own cloud account.

Performance, accessibility and security

We set performance budgets aligned with Google’s Core Web Vitals, build to WCAG 2.2 AA, and follow the OWASP Top 10 for application security: strong authentication, role-based access, encryption in transit and at rest, and audit logging where the data warrants it.

How much does web application development cost?

As a planning range, a focused web app or internal tool commonly costs roughly $25,000-$75,000, a customer-facing portal or platform roughly $75,000-$200,000, and complex SaaS or marketplace platforms more. Hosting and support are ongoing monthly costs.

Why choose Progression Agency to build your web app?

• One team for strategy, UX, engineering, hosting and launch.
• You own the code, data and cloud accounts.
• Written scope and estimate before development.
• Working releases every two weeks.
• Public-facing pages built to rank, with our SEO and AEO teams involved.
• Headquartered in New York City, working with clients nationwide and worldwide.

Related services

See also custom software development, website design and development, ecommerce development and website maintenance.

Website and web app development services

Website app development services combine a public website with the application behind it — accounts, dashboards, booking, payments or a client portal. As a web app development firm we build both halves so the marketing site and the product share one design system, one login and one set of analytics.

Web software development

Web software development covers any software delivered through a browser, from a small internal tool to a multi-tenant SaaS platform. It is usually the fastest way to reach every device at once.

Choosing a website and application development company

Look for a firm that can design and build the website, the web application and the integrations between them, and that will host everything in accounts you own.

Web application examples by industry

Every industry has recurring web app patterns. These are the ones we build most often.

Single-page apps, multi-page apps and hybrid rendering

Single-page apps load once and update in place, which suits dashboards and tools; server-rendered pages load fast and are easy for search engines to read, which suits public content. Frameworks such as Next.js combine both, which is why we use them for most projects.

Choosing between REST and GraphQL

REST is simple, cache-friendly and widely understood; GraphQL lets clients request exactly the data they need, which helps apps with many screens and a mobile client. We choose per project and document the reason.

Web app hosting and running costs

Most web apps run on managed cloud services billed by usage. Small internal tools often cost tens to a few hundred dollars a month to host; high-traffic platforms cost more. We model hosting cost during architecture so there are no surprises.

Progressive web apps

Web application development services: what we build and how we scope it

Our web application development services cover the full product: discovery and scope, UI/UX design, front-end engineering in React and Next.js, back-end and API development, integrations, testing, deployment and support. Custom web application development services suit products that off-the-shelf software cannot fit, and enterprise web application development services add single sign-on, role-based access, audit logging, compliance controls and integration with systems of record.

Choosing the stack and the hosting is part of the service: see how we choose a tech stack, web development frameworks, rendering strategies and where we host React and Next.js apps. For the architecture question that comes up on every larger build, read monolith vs microservices.

What is the difference between a web application and a website?

A website presents information and is mostly the same for every visitor; a web application lets users log in, work with their own data and complete tasks, such as a portal, dashboard, marketplace or SaaS product. Most web applications also have a public website in front of them, and we commonly build both on one Next.js codebase.

What do custom web application development services include?

Scope and product design, front-end and back-end engineering, integrations with your systems, security and compliance work, automated testing, deployment and hosting setup, and support after launch.

• React development company: React and Next.js engineering for web applications, plus dedicated React developers.
• Next.js development company: server-rendered products and portals on the App Router.
• Front-end development company: React, Angular, Vue and TypeScript interfaces and design systems.
• SaaS hosting: architecture and providers by stage, from first customers to enterprise.
• DevOps services: CI/CD, infrastructure as code and managed operations for the app after launch.
• Website and web app development cost: planning ranges by project type.

When users should install the app without visiting a store, we build it as a progressive web app: installable, offline-capable and push-enabled from the same codebase. See progressive web app development.

Frequently asked questions