I built an expense tracker in WhatsApp because I couldn't stop abandoning apps. Here's what I learned about intentional friction.

The problem I kept having
I've tried every expense tracker. I'd set it up, use it for four days, and abandon it. Not because the apps were bad — because the habit never stuck. Opening a separate app to log something I just spent money on requires a context switch that never becomes automatic.

The apps that removed friction entirely (auto-reading bank SMS, auto-categorising everything) were the worst for me. Technically impressive. Completely useless for changing how I spent. I'd get a beautiful monthly report and feel vaguely informed without having done anything differently.
The thing I realised

The auto-tracking apps are solving the wrong problem. They're optimising for accurate data collection. But the reason people want to track expenses isn't to have accurate data — it's to spend more intentionally.

There's research on payment salience showing that frictionless payment methods reduce how psychologically real a purchase feels. I think the same principle applies to tracking: when your ₹680 dinner gets silently auto-categorised, you were never present for the acknowledgment. You're informed, not aware.

Manual logging forces a pause. You type "dinner 680 barbeque nation" and for four seconds you're choosing to notice what you just did. That's the behaviour change mechanism. Not the report it generates.
What I built

Budgy — a WhatsApp expense tracker where the friction is deliberate.

Text the number: "lunch 280 swiggy" → logged, categorised, running total
Send a receipt photo or bank SMS screenshot → parsed via Claude Vision
Drop a PDF bank statement → imports, deduplicates, confirms with you before logging anything
Ask "how much on Swiggy this cycle?" → answers in natural language

It also nudges you. Not just a daily reminder — smart nudges that know your spend pace relative to how many days are left until payday. "You're 31% above pace with 18 days to go" is a different message than "you've been good this week, payday is in 4 days."

The India-specific insight that made me feel dumb for not noticing earlier
Every budgeting app tracks by calendar month. My salary doesn't land on the 1st. It lands on the 27th or 28th. So "April" for me runs from March 27th to April 28th.

Every app I've ever used has been lying to me about how much of my budget I've used, because they're measuring the wrong interval. Budgy tracks against your actual salary cycle. Summaries say "Mar 27 → Apr 28." Nudges and spend baselines are calculated from your real payday. This is obvious in retrospect and somehow nobody's done it.

Stack and numbers
Node.js/Express → Render. Twilio for WhatsApp. Claude API for parsing, vision, and conversation. Google Sheets as data store (users own their sheet). node-cron for scheduled nudges.
Currently: one user (me), using it daily. Opening early access now. ₹149/month when paid plan launches. Free during early access.

What I'm unsure about
The manual-logging-as-feature philosophy works for me but I genuinely don't know if it's a market. Most people, when they hear "you have to manually log," hear "inconvenient." I believe the inconvenience is the value — but that's a hard thing to market.

If you've tried auto-tracking apps and found them useless for changing behaviour, I'd love to know. And if you think I'm wrong about the friction argument, also want to hear it.

Early access at budgy.in.