Custom Software Development and Maintenance Services

Custom software development means building the application your organization needs when nothing on the market fits: a customer portal, an internal tool that replaces a spreadsheet chain, a mobile app, a product you intend to sell, or a system that connects the ones you already run. PS3G has done this work for more than ten years for organizations of every size, whether you are a founder with a first version to build, an operations lead replacing manual processes in a growing company, or an IT director inside a large organization with a legacy system to replace. We scope the work to the problem, build it on a stack you can hire for, hand you the code, and then maintain it, because software that nobody maintains stops being an asset within a year.

Custom software, scoped to the problem

Off-the-shelf software is the right answer more often than custom software vendors admit. We say so in the first call when it is true. Custom development earns its cost in three situations: the process is specific to how you compete, the data has to flow between systems that do not talk to each other, or the product is the business and you need to own it.

Scoping is where most projects go right or wrong. We start with the outcome (fewer hours spent on intake, orders that do not need re-keying, a product customers will pay for), then work back to the smallest system that delivers it.

A founder gets a first version that proves the idea without paying for features nobody has asked for. A growing company gets a system that fits its process rather than forcing a new one. A division inside a larger group gets a build that passes its security and procurement review. The engineering is the same; the scope is different.

What we build

• Web applications. Customer, partner and employee portals, workflow and approval systems, dashboards, booking and quoting tools. See web application development for the detail, and website development when the need is a marketing site or content platform rather than an application.
• Mobile apps. Native iOS and Android, or cross-platform in React Native and Flutter, with the back end and the store submissions handled. Covered under mobile app development.
• .NET, Java, PHP and Python systems. Line-of-business applications, APIs and services on the stack that fits your team. Our .NET development practice covers ASP.NET Core, Blazor, Azure and SQL Server in depth.
• Integrations. Connecting your ERP, CRM, accounting, e-commerce, payment, shipping and industry-specific systems through APIs, message queues, file exchange and EDI, so data is entered once.
• SaaS products. Multi-tenant platforms with subscription billing, role-based access, audit trails and an admin layer, built with the operating costs and the security questionnaires of a product business in mind. We build and run two products of our own, so we know what the second year looks like.
• Internal tools. The unglamorous systems that run a business: inventory, scheduling, field-service, compliance tracking, reporting. Often the highest return per dollar of custom software.
• Regulated applications. Software that handles health, financial or government data, built with the controls those sectors require. Our healthcare software development page explains the HIPAA-by-design approach.
• Replacements for legacy systems. Rebuilding or re-platforming an application that has reached the end of its supported life, covered under application modernization.

Our process: discovery, design, build, test, launch, maintain

The phases below are the ones we have used on client projects for years. The output of each phase is a document or a working increment you can review, not a status update.

1. Discovery. Requirements workshops with the people who will use the system, a project charter with stakeholders named, a review of the systems the new one must talk to, and a prototype where a picture settles an argument faster than a paragraph. Discovery ends with a scope, an estimate and a plan you approve before build starts.
2. Design. Technical architecture (data model, integration points, hosting, security controls), interface designs tested with real users, and the backlog broken into increments with the riskiest items first.
3. Build. Development in short iterations, each ending in a working demo on a test environment you can log into. Code review on every change, automated tests written alongside features, and a repository you own from the first commit.
4. Test. Our testing center of excellence runs functional, regression, automated, performance and security testing against agreed acceptance criteria. See software testing and QA services for how that works, including for software we did not build.
5. Launch. Deployment runbooks, data migration with rehearsals, user training, documentation and a rollback plan. Go-live happens on a date you choose, with our engineers on call.
6. Maintain. Post-launch support, monitoring, patching, small enhancements and periodic health reviews, under a maintenance agreement with defined SLAs.

Get a fixed-scope quote for the system you have in mind.

Maintenance and support after launch

Many software development companies hand over the code and move on. We treat maintenance as part of the service, because the first year after launch is when a system either becomes part of how you work or quietly decays. “We maintain it” means specific things:

• Corrective maintenance. Bugs found in production are triaged by severity, fixed, tested and deployed, with a record of what changed.
• Preventive maintenance. Framework, library, runtime and operating-system updates applied on a schedule, security advisories reviewed, and dependencies kept within supported versions.
• Adaptive maintenance. Changes forced from outside: a payment gateway retires an API, a browser drops a feature, a regulation changes a form, a partner moves to a new file format.
• Enhancements. Small features and improvements batched into releases, prioritized with you against a budget you control.
• Monitoring and support. Uptime, error and performance monitoring with alerts routed to engineers; a support channel with response targets defined in the agreement; and a monthly report of incidents, changes and recommendations.
• Knowledge. Up-to-date documentation, architecture notes and runbooks, so that a new engineer (ours or yours) can take over without archaeology.

Our India delivery center gives maintenance agreements round-the-clock coverage with US-based management and escalation. For websites and content platforms, the same discipline is offered as website maintenance and support. These are application support services in the practical sense: someone owns the system’s health, and you can see what they did.

Technology choices: Microsoft and open source, and you own the code

We are certified on the Microsoft stack and on open-source stacks, and we recommend based on your team, your existing systems and your hiring market, not on what we would prefer to write. A company whose IT team lives in Microsoft tools usually gets ASP.NET Core, SQL Server and Azure. A startup that expects to hire from a general web talent pool often gets Node.js or Python with PostgreSQL and React. Both are good answers; the wrong answer is the one you cannot staff.

Layer	Microsoft stack	Open-source stack
Back end	ASP.NET Core, C#, Entity Framework	Node.js, Python (Django, FastAPI), PHP (Laravel), Java (Spring)
Front end	Blazor, React with TypeScript	React, Angular, Vue, HTML5 and CSS
Mobile	.NET MAUI	React Native, Flutter, native Swift and Kotlin
Data	SQL Server, Azure SQL, Cosmos DB	PostgreSQL, MySQL, MongoDB, Cassandra, Redis
Cloud and DevOps	Azure, Azure DevOps, Bicep	AWS, Google Cloud, GitHub Actions, Terraform, Docker, Kubernetes

Whatever the stack, the terms are the same. The source code, the infrastructure definitions, the designs and the documentation are yours, in a repository under your account, from the start of the project. There is no license fee for the software we build and no dependency on us to keep running it.

Engagement models

• Fixed-scope project. A defined deliverable at a fixed price, with change requests priced separately. Best when discovery has produced a clear scope.
• Dedicated team or staff augmentation. Engineers, testers and a project lead who work as part of your team on a monthly basis and scale up or down. See IT staff augmentation and dedicated teams.
• Managed services. We run, monitor and support the application under an SLA after launch, or take over a system someone else built.
• Advisory. Architecture reviews, build-versus-buy decisions, technology roadmaps and fractional CTO support.

How we start: a first conversation, a short assessment, a written proposal.

Why PS3G

We are a product company as well as a custom software development company. We built and run our HIPAA-compliant EHR and telehealth platform, DocVilla, used by medical practices across multiple states, and our kids’ learning app, EasyLearning4Kids, with 5-star ratings on the App Store and Google Play. Running our own software for years is why we take maintenance seriously: we know what breaks, what costs money at scale and what customers complain about.

The firm has been delivering for more than ten years from a US headquarters in Wilmington, Delaware and an India delivery center. Our engineers hold Microsoft and open-source certifications, our testing center of excellence tests what we build and what others build, and our project history includes connected-device work (an IoT fall-detection footwear system for seniors) and AR/VR applications for education, healthcare and entertainment.

Guides on this topic

• Build vs Buy Software: How to Decide
• Software Development Pricing Models Explained
• RFP Template for Software Development
• SaaS vs Custom Software

Related services

• Web application development: portals, workflow systems and dashboards.
• Mobile app development: iOS, Android and cross-platform apps.
• .NET development: ASP.NET Core, Blazor, Azure and SQL Server.
• Software testing and QA: independent testing for any application.
• Application modernization: replacing or re-platforming legacy systems.
• Staff augmentation: add engineers to your own team. Browse all services.

Frequently asked questions

How much does custom software development cost?

It depends on scope, integrations, the number of user roles and screens, regulatory requirements and how much of the design already exists. We do not publish rates. After a first conversation and a short assessment we send a written proposal with a fixed price for a defined scope, or a monthly cost for a dedicated team, so you can compare it with alternatives before committing.

How long does a custom software project take?

A focused internal tool or a first version of a product can be a matter of weeks of build after discovery. A multi-role platform with several integrations takes months, delivered in increments you can use along the way. The written proposal includes a phase plan with dates; we do not quote timelines before discovery because guesses made then are the ones projects miss.

Who owns the code and the intellectual property?

You do. The agreement assigns the intellectual property in the custom work to you, the repository is created under your account, and the infrastructure runs in your cloud subscriptions. Open-source components keep their own licenses, which we document. You can take the system to another team at any time, and we design and document it so that a handover is practical.

Do you work with an existing in-house team?

Yes. Many projects are a mix: your team owns the product direction and part of the code, and ours adds capacity, a specialty (mobile, .NET, integration, testing) or a full delivery team for a defined project. We adopt your repositories, tools and review process where you have them, and we set them up where you do not.

What does software maintenance include and how is it priced?

A maintenance agreement covers corrective fixes, security and dependency updates, monitoring, a support channel with defined response targets, and a budget for small enhancements, reported monthly. It is priced as a monthly retainer sized to the system and the support hours you need, with larger changes quoted separately. The scope and SLAs are written into the agreement rather than this page.

Can you take over software another company built?

Yes. We start with a code and infrastructure assessment: what the system does, how it is deployed, where the risks are, and what documentation exists. You get a written report with a stabilization plan. From there we can maintain the system as it is, improve it in stages, or plan a replacement through our application modernization service if that is the better path.