Why I Stopped Using Expense Apps and Built a WhatsApp Bot Instead

I have tried every expense tracking app you can think of.

Money Manager. Walnut. ET Money. YNAB. Even plain Excel. Every January I would download something new, enter my expenses religiously for about 11 days, and then quietly stop.

The apps were not bad. My habit was.

The Real Problem Was Friction

Think about it. You just paid ₹80 for a cutting chai at the station. You are already walking towards the platform. Your train is in 3 minutes.

To log that ₹80, you need to unlock your phone, find the app (it is always buried somewhere), open it and wait for it to load, tap "Add Expense", select category, type amount, add description, and save.

By that time your train has left and you have already forgotten about the chai.

This is why most expense apps fail. Not because they are badly built. Because opening a dedicated app to log ₹80 feels like too much work for too small a transaction.

And it is the small transactions that kill your budget. The chais. The auto rides. The random Amazon purchases at midnight.

WhatsApp Is Already Open

One day I was chatting with a friend on WhatsApp and I thought — what if I could just send a message to track expenses? No app switching. No loading screens. Just type and done.

I already have WhatsApp open 40 times a day. Why not use that?

So I built Spendly.

How It Works

You just send a message. That is it.

coffee 80

Done. Logged. ₹80 under Food.

paid 1200 electricity bill upi

Done. ₹1,200 under Utilities, payment method UPI.

how much did I spend this month?

It tells you. With breakdown by category.

food vs transport last 2 weeks

It compares. Conversationally.

You can even set reminders:

electricity bill due 10th remind me

And it will message you the day before.

No categories to select. No forms to fill. No app to open.

The AI Does the Thinking

Behind every message is Claude — Anthropic's AI. It understands what you mean, not just what you type.

"paid petrol full tank 1500" → it knows this is Transport, ₹1500, expense.

"salary credited 85000" → it knows this is Income.

"zomato yesterday 340" → it knows yesterday's date automatically.

You do not have to be precise. You do not have to follow any format. Just type how you think.

What Surprised Me

I thought the hardest part would be the technology. It was not.

The hardest part was deciding what NOT to build. Every week I had 10 new feature ideas. Charts. Goals. Investment tracking. Bank integration.

But the product's whole point is zero friction. Every feature adds friction. So I kept cutting.

The result is something that does very little — but does it so smoothly that people actually use it.

The code is open source under AGPL-3.0 if you want to see how it is built: github.com/knamburi/spendly