This is Part 4 of the How Software Engineering Works series. We are building a task management app (think simplified Trello) from scratch.

You have identified the problem. You have brainstormed solutions. Now comes the step most developers skip entirely: validation. Before you write a single line of production code, you need proof that your solution is worth building.

Why Validate Before Building?

Building the wrong thing is the most expensive mistake in software engineering. It is not a bug you can patch in a sprint. It is weeks or months of wasted effort, burned budget, and team morale damage. Studies consistently show that 70-80% of features in enterprise software are rarely or never used.

Validation is cheap. Building is expensive. A week of validation can save you six months of building something nobody wants. As a senior developer, I treat validation as a non-negotiable phase, not an optional nice-to-have.

Validate the Problem

Before you validate the solution, validate the problem itself. Do real users actually experience the pain you think they do?

For our task management app, the question is: Do small teams really struggle with task tracking?

Here is how you find out:

• User interviews – Talk to 5-10 people in your target audience. Ask open-ended questions. “How do you currently track tasks?” not “Would you use a task management app?”
• Surveys – Send a short survey to a broader group. Keep it under 5 questions. Focus on their current pain, not your proposed solution.
• Competitor analysis – If Trello, Asana, and Jira exist, the problem is validated. But are they solving it well for your target audience? Small teams often find Jira bloated and overwhelming.

If nobody confirms the problem exists, stop. You just saved yourself months.

Validate the Solution

The problem is confirmed. Now test whether your specific approach solves it. You do not need code for this.

• Paper prototypes – Sketch your UI on paper. Put it in front of users and ask them to “use” it. You will learn more in 30 minutes than in 30 days of coding.
• Mockups – Use Figma or Balsamiq to create clickable wireframes. Share them and watch how people interact with the design.
• Landing page test – Create a simple landing page describing your app. Add a “Sign up for early access” button. If nobody signs up, your solution does not resonate.
• Fake door test – Add a button for a feature that does not exist yet. Measure how many people click it. High clicks mean high demand.

For our task management app, we might create a simple mockup showing boards, columns, and drag-and-drop cards. If test users say “this looks just like Trello,” we know we need stronger differentiation.

Technical Feasibility

Can your team actually build this? Before committing, build a proof of concept (POC) for the hardest technical piece. Do not build the whole app. Build the one thing you are least sure about.

For our app, the riskiest part might be real-time collaboration. Can we sync task updates across multiple users instantly? Let us write a quick POC to find out.

Here is a minimal Java prototype, an in-memory task store to validate the core concept quickly:

import java.util.*;
import java.util.concurrent.ConcurrentHashMap;

// Throwaway POC - NOT production code
public class TaskStorePOC {

    private final Map> tasks = new ConcurrentHashMap<>();

    public String createTask(String title, String assignee) {
        String id = UUID.randomUUID().toString().substring(0, 8);
        Map task = new HashMap<>();
        task.put("id", id);
        task.put("title", title);
        task.put("assignee", assignee);
        task.put("status", "TODO");
        task.put("created", System.currentTimeMillis());
        tasks.put(id, task);
        return id;
    }

    public Map getTask(String id) {
        return tasks.get(id);
    }

    public void moveTask(String id, String newStatus) {
        Map task = tasks.get(id);
        if (task != null) {
            task.put("status", newStatus);
        }
    }

    public List> getTasksByStatus(String status) {
        List> result = new ArrayList<>();
        for (Map task : tasks.values()) {
            if (status.equals(task.get("status"))) {
                result.add(task);
            }
        }
        return result;
    }

    public static void main(String[] args) {
        TaskStorePOC store = new TaskStorePOC();
        String id1 = store.createTask("Design database schema", "Alice");
        String id2 = store.createTask("Set up CI/CD pipeline", "Bob");

        store.moveTask(id1, "IN_PROGRESS");

        System.out.println("TODO: " + store.getTasksByStatus("TODO"));
        System.out.println("IN_PROGRESS: " + store.getTasksByStatus("IN_PROGRESS"));
    }
}

And the same concept in Python, a quick throwaway prototype using a dictionary:

import uuid
from datetime import datetime

# Throwaway POC - NOT production code
tasks = {}

def create_task(title, assignee):
    task_id = str(uuid.uuid4())[:8]
    tasks[task_id] = {
        "id": task_id,
        "title": title,
        "assignee": assignee,
        "status": "TODO",
        "created": datetime.now().isoformat()
    }
    return task_id

def move_task(task_id, new_status):
    if task_id in tasks:
        tasks[task_id]["status"] = new_status

def get_tasks_by_status(status):
    return [t for t in tasks.values() if t["status"] == status]

# Quick validation
id1 = create_task("Design database schema", "Alice")
id2 = create_task("Set up CI/CD pipeline", "Bob")
move_task(id1, "IN_PROGRESS")

print("TODO:", get_tasks_by_status("TODO"))
print("IN_PROGRESS:", get_tasks_by_status("IN_PROGRESS"))

Notice these prototypes use in-memory storage. No database, no API layer, no authentication. That is intentional. This code exists to answer one question: does the core data model work? If it does, we move forward. If it does not, we pivot before investing in infrastructure.

Market Validation

Technical feasibility is only half the equation. Is there a market for this?

• Competitor landscape – Trello (simple, visual), Asana (mid-range), Jira (enterprise). Where is the gap? For our app, the gap might be teams of 2-5 people who want something simpler than Trello with built-in time tracking.
• Differentiation – If you cannot finish the sentence “Unlike [competitor], our app…” then you do not have a differentiator. That is a red flag.
• Willingness to pay – Ask potential users directly: “Would you pay $5/month for this?” Watch their reaction. Polite interest means no. Genuine excitement means maybe.

Build a Prototype

Once problem, solution, technical feasibility, and market are validated, build a throwaway prototype. This is not production code. This is a tool to test your remaining assumptions with real users.

Key rules for prototypes:

• Time-box it to 1-2 weeks maximum
• Skip authentication, error handling, and edge cases
• Hard-code what you can
• Use the fastest tools available, not the “right” tools
• Plan to throw it away completely

The goal is learning speed, not code quality. If your prototype validates the remaining assumptions, you now have confidence to invest in building the real thing.

Senior Tip

Fall in love with the problem, not the solution.

The most dangerous trap in engineering is emotional attachment to your solution. I have seen senior engineers spend months defending an architecture that users do not want, simply because they already built it. Validation exists to protect you from this. If your research shows users need something different from what you proposed, that is not failure. That is the process working exactly as it should. Be willing to pivot. The best engineers I have worked with treat every assumption as a hypothesis to be tested, not a truth to be defended.

Next up: Part 5 – Planning, where we turn our validated solution into an actionable roadmap.