Building a Dynamic Profile Endpoint

#backend #hng #programming #opensource

By Otuoniyo Ufuoma-Oghene Humphery

Introduction

As part of the HNG 2025 Backend Wizards program, I recently completed Stage 0, where the task was to build a dynamic profile endpoint. The goal was simple yet powerful: create a RESTful API endpoint that returns my profile information along with a random cat fact fetched from an external API.

This task taught me not just the technicalities of building endpoints, but also how to consume third-party APIs, handle dynamic data, and structure JSON responses professionally.

Task Overview

Requirements:

Create a GET endpoint at /me.
Return JSON with Content-Type: application/json.
Include a dynamic cat fact fetched from Cat Facts API.
JSON response format:

{
  "status": "success",
  "user": {
    "email": "<your email>",
    "name": "<your full name>",
    "stack": "<your backend stack>"
  },
  "timestamp": "<current UTC time in ISO 8601 format>",
  "fact": "<random cat fact from Cat Facts API>"
}

Handle API errors gracefully.
Follow best practices for code structure, environment variables, and logging.

My Work Process

Here’s how I approached this task step by step:

1. Setting Up the Server

I used Node.js and Express for this project. First, I initialized the server and created a simple route handler for /me.

app.get("/me", getUsers);

2. Fetching Dynamic Cat Facts

I implemented a fetchWithTimeout utility to safely fetch data from the Cat Facts API, handling timeouts and network errors:

const catFactJson = await fetchWithTimeout(CAT_API_URL);
const catFact = catFactJson?.fact || "Could not fetch a cat fact right now.";

This ensures the endpoint never crashes, even if the external API is down.

3. Formatting the JSON Response

Next, I structured the JSON response to strictly match the Stage 0 requirements:

res.json({
  status: "success",
  user: {
    email: "humpheryufuoma@gmail.com",
    name: "Otuoniyo Ufuoma-Oghene Humphery",
    stack: "Node.js/Express"
  },
  timestamp: new Date().toISOString(),
  fact: catFact
});

I made sure the timestamp was dynamic and in UTC ISO 8601 format.

4. Environment Variables

For local development, I used .env to store the Cat Facts API URL:

CAT_API_URL=https://catfact.ninja/fact

Note: Railway automatically adds quotes to environment variables, so in production I strip them in code before using the URL.

5. Handling Errors Gracefully

I added error handling to ensure a fallback cat fact is returned if the API fails:

catch (err) {
    res.status(500).json({
        status: "error",
        message: "Failed to fetch cat fact"
    });
}

This guarantees a smooth user experience at all times.

Lessons Learned

Environment variables are crucial for separating config from code, but deployment platforms like Railway may add quirks (like automatic quotes) that you need to handle.
Dynamic data fetching requires proper error handling — always expect the external API to fail occasionally.
JSON schema validation is important; even small typos in field names can break automated checks.
Small tasks teach discipline: Stage 0 reinforced best practices in endpoint design, logging, and clean code.

Screenshots / GIFs

Outcome

The final endpoint returns JSON like this:

{
  "status": "success",
  "user": {
    "email": "humpheryufuoma@gmail.com",
    "name": "Otuoniyo Ufuoma-Oghene Humphery",
    "stack": "Node.js/Express"
  },
  "timestamp": "2025-10-18T19:50:29.028Z",
  "fact": "A cat usually has about 12 whiskers on each side of its face."
}

Meets all Stage 0 requirements.
Dynamic timestamp and cat fact.
Graceful error handling.
Ready for deployment on Railway.

Conclusion

Stage 0 of HNG Backend Wizards was packed with learning: working with REST APIs, dynamic data, and deployment quirks.

I’m excited to carry these best practices forward into Stage 1 and beyond, building more complex backend systems that are robust, maintainable, and dynamic.