Web, APIs & SaaS Products
Custom Software Development
Software built around your business, not the other way around. We design, build, and evolve custom web applications, internal platforms, APIs, and SaaS products end-to-end — senior engineering, modern architecture, and nearshore delivery aligned to your time zone.
Outcomes
What this gets you
Custom software development builds the system your process actually needs — not the closest off-the-shelf compromise. OneSolution America designs and ships web applications, APIs, and SaaS products with senior nearshore engineers working US hours.
- Replace brittle spreadsheets and off-the-shelf gaps with software that fits your process
- Ship faster with senior engineers, modern architecture, and iterative demos you can steer
- Scale from MVP to production without re-platforming halfway through
- Off-the-shelf tools cover 80% of your process — and the missing 20% costs the most
- A business-critical spreadsheet has quietly become a system of record
- Your product outgrew the freelancers or agency who started it
- A legacy application is holding the business back, but a rewrite feels too risky
Who this is for
The problems we’re brought in to solve
If any of these sound like your Monday, this practice was built for you.
Typical engagement
Projects start with a 1–2 week technical discovery that produces an architecture and a costed roadmap — then iterative releases you can steer, with a working demo every sprint.
What we deliver
Capabilities in this practice
Web application development
Modern SPA and SSR frontends in React and TypeScript, backed by robust .NET services — fast, accessible, and built to maintain.
APIs & systems integration
REST APIs, webhooks, and event-driven architectures that connect ERPs, CRMs, and legacy systems into one reliable flow.
SaaS product development
From MVP to scale — multi-tenant architecture, billing, and the roadmap discipline to get a product to market and grow it.
Cloud-native on Azure
App Services, Azure SQL, and Blob Storage with Entra ID authentication — secure, elastic, and cost-aware from day one.
Legacy modernization
Re-platform aging applications incrementally — no risky big-bang rewrites, no interruption to the business.
AI-enabled applications
Embed LLMs, intelligent document processing, and automation directly into your product, in step with our AI Solutions practice.
Built on
A modern, cloud-agnostic toolchain
- .NET
- C#
- React
- TypeScript
- Azure
- SQL Server
Explore related practices
All services →AI Solutions
Production-grade AI that ships — from copilots and RAG assistants to forecasting and document intelligence, built on Azure OpenAI, AWS Bedrock, or the right model for your stack, and governed for the enterprise.
UX & Product Design
Research-led product and interface design that makes complex enterprise software feel effortless — and turns adoption from a hope into a metric.
Dedicated Squads / Staff Augmentation
Senior, nearshore squads that plug into your roadmap and ship — data engineers, AI developers, BI specialists, and designers in US-aligned time zones.
FAQ
Frequently asked questions
The questions buyers ask us before an engagement — answered straight. Anything we missed? Ask us directly.
What technology stack do you build on?
.NET and C# on the back end, React and TypeScript on the front, Azure as our default cloud — with AWS and Google Cloud when that’s where you live. Boring, proven technology chosen for the decade of maintenance ahead, not the conference talk.
How does nearshore development work day to day?
Our engineers in São Paulo and Rio work US-aligned hours, so they join your stand-ups, reviews, and incident calls live. You get the cost profile of offshore with the collaboration rhythm of an in-house team.
Can you take over an existing codebase?
Yes. We start with a short technical assessment — architecture, test coverage, deployment, risk hotspots — and give you an honest read on what to keep, refactor, or replace before committing to a roadmap.
Who owns the code and IP?
You do, fully and from day one. Code lives in your repositories, runs in your cloud accounts, and every contract makes work-for-hire ownership explicit.
Should we start with an MVP or the full product?
An MVP — but architected so it scales. The expensive mistake isn’t starting small; it’s starting small on foundations that force a re-platform at exactly the moment the product succeeds. We make the multi-tenant, auth, and data decisions early so growth doesn’t mean a rewrite.
Book a Consultation
Ready to put Custom Software Development to work?
Book a 30-minute consultation. We’ll map your highest-value data and AI opportunities — and show you exactly what the first 90 days could deliver.