Seattle Software Agency SeattleSoftware Agency

Web Application Development

Full-stack web applications built with modern technology, designed for scale, and engineered to last.

A web application is not a website. It is software that runs in the browser — complex, interactive, and critical to your business. Whether you are building a SaaS platform, a customer portal, an e-commerce system, or a specialized business tool, the quality of the engineering determines whether your product delights users or frustrates them.

We build custom web applications for businesses that have outgrown off-the-shelf solutions. Our stack — React with Next.js on the frontend, Node.js with TypeScript on the backend, PostgreSQL for data — is chosen for reliability, performance, and the depth of the available talent pool. No exotic frameworks that make hiring difficult, no bleeding-edge tools that break on updates.

Every project is built with the same standards: type safety throughout, comprehensive testing, automated deployments, and documentation that makes the codebase accessible to any competent developer.

What You Get

🏗️

Full-Stack Development

React frontend + Node.js backend + PostgreSQL database — a cohesive application built by a single team with consistent patterns and shared TypeScript types.

🔐

Authentication & Multi-Tenancy

Secure user management with Clerk or Auth0, role-based access control, organization/team structures, and data isolation for multi-tenant SaaS applications.

💳

Payment & Billing

Stripe integration for subscriptions, usage-based billing, one-time payments, invoicing, and customer portal — handling the full billing lifecycle.

📧

Transactional Email

Automated emails for onboarding, notifications, receipts, and alerts using SendGrid or Resend with templated, branded email designs.

📊

Admin & Back-Office

Administrative interfaces for managing users, content, configurations, and business operations — built alongside the customer-facing application.

🚀

Performance & SEO

Server-side rendering, image optimization, code splitting, and Core Web Vitals optimization for applications that need to be fast and discoverable.

Our Technology Stack

We use a consistent, modern technology stack across all web application projects. The frontend is React with Next.js, providing server-side rendering for SEO and performance, file-based routing for simplicity, and API routes for backend-for-frontend patterns. Styling is done with Tailwind CSS for rapid, consistent UI development.

The backend runs on Node.js with TypeScript, using Fastify or Express for HTTP handling and Prisma for database access. PostgreSQL is our default database, chosen for its reliability, feature set (JSON, full-text search, GIS), and the maturity of its tooling. Redis handles caching, sessions, and job queues.

This stack is not chosen because it is trendy — it is chosen because it works at scale, has excellent developer tooling, a massive talent pool for future hiring, and has been battle-tested across thousands of production applications.

Building for Scale from Day One

Premature optimization is a real problem, but so is premature architecture. We design applications to handle 10x your current load without architectural changes — not because you will need it tomorrow, but because the cost of building it right from the start is marginal compared to the cost of a rushed re-architecture later.

This means: stateless application servers that can scale horizontally, database schemas designed with proper indexes and query patterns in mind, background job processing for anything that takes more than 200ms, and caching at the appropriate layers. These patterns add minimal development time but provide enormous breathing room as your application grows.

For SaaS applications specifically, we implement multi-tenancy patterns, subscription management, usage tracking, and feature flagging as foundational infrastructure — not afterthoughts that need to be retrofitted later.

Quality Assurance and Ongoing Support

Every web application we build has a comprehensive QA process. Automated tests (unit, integration, and end-to-end with Playwright) run on every pull request. Before launch, we conduct accessibility audits (WCAG 2.1 AA), performance audits (Core Web Vitals in green), security reviews (OWASP top 10), and cross-browser testing. After launch, we monitor error rates with Sentry and set up alerting for anomalies.

Launching a web application is the beginning, not the end. The most successful products iterate continuously based on user feedback, usage data, and business requirements. We offer ongoing development retainers for feature development, bug fixes, and performance optimization. For teams that want to bring development in-house after launch, we provide thorough handoff documentation and onboarding sessions for your development team.

Technologies We Use

ReactNext.jsTypeScriptNode.jsPostgreSQLPrismaStripe

Frequently Asked Questions

How long does it take to build a web application?
A focused web application with core functionality (authentication, a primary workflow, basic admin panel) takes 8-14 weeks. A full-featured SaaS platform with billing, multi-tenancy, extensive integrations, and a polished UI takes 14-24 weeks. We deliver incrementally, so you see working software within the first 2-3 weeks.
What does a custom web application cost?
Projects typically range from $30,000 to $120,000 depending on complexity. A basic business application with authentication and core CRUD functionality starts around $30,000. A full SaaS platform with billing, multi-tenancy, integrations, and comprehensive admin capabilities is $60,000-$120,000. We provide detailed estimates after a discovery session.
Can you rebuild our existing application?
Yes. We frequently rebuild applications that have outgrown their original technology or architecture. We use a phased approach — rebuilding the most critical parts first while keeping the existing application running — to minimize risk and deliver value incrementally.
Do you provide hosting and maintenance after launch?
Yes. We typically deploy to Vercel (frontend) and Railway or AWS (backend), and offer ongoing maintenance retainers for updates, bug fixes, and feature development. Hosting costs are usually $50-$300/month depending on traffic and infrastructure requirements.

Ready to Build Something That Scales?

Tell us about your project. We will help you define the scope, choose the right approach, and deliver a web application your business can grow with.

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