MCMaría Isabel CastañoAI Systems Developer

Custom Web Applications for Business Operations

Software designed around how your business actually works.

When generic software no longer fits the operation, I build custom web applications that bring workflows, data, business rules and integrations into one purpose-built system.

Custom software is most valuable when the workflow itself is part of the business advantage.

The operational problem

A business should not have to redesign itself around a generic tool.

Custom web applications make sense when the process is specific enough that spreadsheets, plugins and off-the-shelf products have become a patchwork instead of a system.

The workflow is uniqueThe process contains business rules, exceptions or handoffs generic software cannot represent cleanly.
Users need different viewsEmployees, customers, vendors or managers require different permissions and actions in the same workflow.
Data needs to moveThe application must connect to existing systems, APIs, databases or automation instead of living in isolation.
Growth exposes workaroundsA process that was manageable manually becomes difficult to control as volume, users or complexity increase.

What I build

Purpose-built applications for operational work.

I build around the workflow first, then choose the simplest architecture that can support it reliably and evolve with the business.

01

Operations platforms

Bring recurring work, tasks, documents, decisions and status into a structured operational environment.

02

Customer & vendor portals

Create controlled external experiences connected directly to the internal workflow.

03

Ordering systems

Combine catalogs, inventory logic, requests, approvals and operational handling in one application.

04

Management dashboards

Connect reporting to the underlying workflow so visibility is part of the system, not a separate manual exercise.

05

Data-driven applications

Create useful interfaces over APIs, business data and automation instead of forcing users to work directly in backend tools.

06

Workflow applications

Translate business states, ownership, rules and exceptions into software that guides the process.

When I’m usually brought in

The business does not need another website. It needs software that helps run the work.

A custom web application becomes valuable when users need to do something operational: manage records, move work through states, place orders, approve requests, coordinate with other roles or connect actions to real business data.

The process has become a patchwork.

Spreadsheets, forms, email, shared drives and SaaS tools each carry one part of a workflow nobody can see end to end.

Different users need different actions.

Employees, customers, suppliers or managers need a shared system with clear roles, permissions and views.

The interface needs business logic behind it.

The application must validate rules, connect data and trigger actions — not simply display information.

Operations-first architecture

Workflow → System → Automation → AI

I do not begin by choosing a tool. I first understand what the operation needs to control, what can be deterministic, what needs judgment and where technology can remove friction without creating another fragile layer.

01Workflow

Map how work actually moves, including rules, exceptions and decisions.

02System

Create the right structure for data, interfaces, permissions and business logic.

03Automation

Connect systems and remove repetitive work that should not require manual effort.

04AI

Add intelligence where classification, extraction, reasoning or assistance creates real leverage.

Proof in practice

A real ordering workflow, turned into a purpose-built web application.

Selected system · B2B operations

Order & Inventory Platform

Catalog browsing, inventory checks and order requests were disconnected from the way customers actually placed orders. I designed a responsive B2B application with inventory validation, persistent cart logic and structured operational order handling.

Result: a clearer ordering experience for customers and a more controlled workflow behind the scenes.

B2B custom web application with product catalog and inventory

Questions

Before building another tool.

How do I know whether I need a custom web app?

A custom application becomes worth evaluating when the workflow is recurring, operationally important and increasingly constrained by spreadsheets or generic software.

Can you build on top of my existing systems?

Yes. A custom application can act as the interface or operational layer while existing services remain responsible for specific functions behind the scenes.

What technology do you use?

Architecture depends on the problem. My stack can include JavaScript, Google Apps Script, Python, Firebase/Firestore, REST APIs, n8n, Make and AI services.

Can a custom app start as an MVP?

Yes. I prefer to establish the smallest reliable operational core first, then add functionality based on actual use.

Do you also handle automation and integrations?

Yes. The application, data flow and automation are designed as one system when the workflow requires them to work together.

Start with the operation

I don’t start with the tool.
I start with the workflow.

Tell me where the operation is becoming difficult to control. You do not need a technical specification — the current workflow is enough to start.

Discuss your operation →