Free Automated Emails for Reminder Using Node.js, Render & Brevo (No Server Costs!) | by S. Hariharan Reddy

🚀 Introduction

Let’s be honest — staying consistent with daily practice or habit-building is tough.

For me, the problem wasn’t learning DSA.
It was revising consistently, every single day.
I’d forget. I’d skip. I’d procrastinate.

So I built a solution that fixes that automatically — a system that sends me 3 Java DSA questions to my inbox every morning, without fail.

And here’s the best part:

✅ It runs entirely on free-tier services
✅ No manual triggers needed
✅ I don’t have to remember — it remembers for me

This guide will walk you through building your own automated daily email reminder app. Whether it’s:

• Quotes

• Goals

• Journaling prompts

• Revision content

• Dev tips

You can fully customize the content. No paid tools. No servers.

📦 Tools & Services Used (All Free)

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📌 What This App Does (Use Case: DSA Mailer)

• Recursively reads .java files from a nested folder (/java-output)

• Sends 3 unsent questions to your email daily

• Logs every sent question in MongoDB to avoid repeats

• Keeps your Render instance awake to avoid cold starts

• Operates entirely on autopilot at ₹0/month

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🛠️ How to Build It — Step by Step

1. ✅ Set Up Your Node.js Project

mkdir dsa-mailer && cd dsa-mailer
npm init -y
npm install express mongoose dotenv sib-api-v3-sdk

2. ✅ Create a .env File

PORT=3000
MONGODB_URI=your_mongodb_uri
YOUR_EMAIL=your_verified_email@domain.com
BREVO_API_KEY=your_brevo_api_key

3. ✅ Core Code (index.js)

This file does the heavy lifting:

• Connects to MongoDB

• Recursively reads .java files

• Selects 3 new, unsent ones daily

• Sends the email via Brevo

• Logs file paths in the DB

👉 View the full code here (Replace with actual GitHub repo link)

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4. ✅ Deploy to Render (Free Tier)

1. Push your code to GitHub

2. Connect your repo to Render

3. Choose “Web Service”

4. Set:

   • Build command: npm install

   • Start command: node index.js

5. Add your .env variables to Render’s dashboard

6. Deploy! 🎉

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5. ✅ Schedule Cron Jobs via cron-job.org

🔄 Wake-Up Cron Job (Every 5 Minutes)

Prevents cold-start issues on Render

*/5 * * * *

URL: https://your-app.onrender.com/

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📨 Daily Email Cron Job (2 AM IST)

Sends 3 new DSA questions

30 20 * * *

2 AM IST = 8:30 PM UTC

URL: https://your-app.onrender.com/send-dsa

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🧠 Challenges Faced & How I Solved Them

💤 1. Cold Start Delay on Render

Problem:
Render free tier sleeps after 15 mins of inactivity → long email delays

Fix:
Ping the base / route every 5 mins using a wake-up cron job. Keeps instance warm.

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📥 2. Cron-job.org “Response Too Big” Error

Problem:
If the /send-dsa route returned a big HTML response, cron-job.org failed to parse it.

Fix:
Send a quick 202 Accepted response immediately. Run the actual mail logic in the background.

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♻️ 3. Preventing Repeated Emails

Problem:
I was getting the same questions again and again.

Fix:
Track sent file paths in a MongoDB collection and skip them during selection.

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🔁 Reuse Ideas: Turn This Into Anything

Want to build a habit or learning bot that reminds you daily? Just swap the content:

• Replace .java files with .txt, .md, or even quotes from an API

• Schedule to email goals, affirmations, or daily journaling prompts

• Add personalization using templates

Examples:

✅ Daily quote email
✅ Daily blog snippet delivery
✅ Morning journal prompts
✅ Custom workout plans
✅ Language learning flashcards

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✨ Final Thoughts

This small project taught me more than I expected:

• Real-world constraints (timeouts, cold starts, rate limits)

• Cron logic in cloud environments

• Email API workflows

• Persistence via database logging

But most importantly — it helped me stay consistent with revision 💪

I now wake up to fresh Java DSA questions in my inbox.
No excuses. Just progress.

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🔗 Grab the Code

👉 GitHub Repo (Full Code) (Replace with your actual GitHub link)
⭐ Star the repo if it helps you!

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🔍 Related Keywords (for SEO)

daily email reminder, free email automation, node.js email app, brevo transactional email, habit builder automation, cron-job.org examples, mongodb daily log, cold start fix render, DSA email bot, productivity side project, self-discipline coding tool

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✅ Want to Build Your Own?

Feel free to clone, tweak, or repurpose.
Let your apps work for you.

Let me know in comments what you plan to send daily to yourself 😄

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