← All answers
What does it cost to automate invoice follow-ups for an Indian SMB?
By Vaibhav Vijay ·
Short answer: About ₹470 a month. That is the running cost of the invoice tracker I built for Ekatra: one small server for the WhatsApp agent, with the web app, database, storage, schedules and email on free tiers.
Where does the ₹470 go?
Monthly running cost of the Ekatra invoice tracker
| Part | Runs on | Monthly cost |
|---|
| Web dashboard | Cloudflare Pages | ₹0, free tier |
| Database | Cloudflare D1 | ₹0, free tier |
| Invoice PDF storage | Cloudflare R2 | ₹0, free tier |
| WhatsApp listener | Hetzner CX23 server, Helsinki | about ₹470 |
| Reminder emails | Gmail API | ₹0 |
| Daily schedules | cron-job.org | ₹0 |
| Total | | about ₹470 |
What does it do for that money?
- Reads every invoice PDF dropped in the sales WhatsApp group
- Checks the amount against the amount-in-words line before saving it
- Shows a live dashboard with ageing buckets and top debtors
- Sends client reminders at 08:00, a CEO digest at 11:00 and owner overdue lists at 13:00 IST
- Emails the owner if the WhatsApp agent stops responding
How long did it take to build?
About two days, using Claude as a pair programmer, against an estimated three to four weekends by hand. It replaced a Google Sheet in April 2026 and has run unattended since.
What are the hidden costs?
Free tiers are only free if you read the limits. An Oracle Cloud "always free" setup billed us 1.38 SGD because of a misconfiguration. A flat-rate server avoids surprise bills.
Related questions
Does it message clients on WhatsApp?
No. It only reads the team's WhatsApp group. Reminders go out by email through the Gmail API, which keeps the WhatsApp number safe from spam flags.
What happens when WhatsApp breaks the integration?
It happened in July 2026. The messaging layer was swapped and the rest of the system kept running. A watchdog emails the owner if the agent goes quiet.
Read next