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Finance / Accounting Small Business

AI Expense Tracker

Turning everyday chat messages into organized financial records. Slack-based expense tracking with natural language input in Greek and English.

5 sec To log expense
95%+ Accuracy
<2% Missing records

The Challenge

Small business owners and busy professionals often struggle with expense tracking. The traditional approach — saving receipts, opening spreadsheet apps, manually categorizing each purchase — creates friction that leads to incomplete records and missed deductions.

Our client needed a solution that would:

  • Eliminate manual data entry for daily expenses
  • Support Greek and English input seamlessly
  • Work within existing workflows (no new apps to learn)
  • Automatically categorize expenses across 14+ categories
  • Generate monthly reports without any additional effort
  • Handle receipt photos alongside text entries

The goal was simple: make expense logging as easy as sending a chat message.

The Solution

We built an intelligent expense tracking system that integrates directly with Slack. Users simply type their expenses in natural language — the AI handles everything else.

How It Works

User types: πρωινό και καφέδες 11 (breakfast and coffee 11)
System extracts:
  • Amount: €11.00
  • Category: Food
  • Title: πρωινό και καφέδες
  • Date: Auto-captured

Built with:

n8n (self-hosted)GPT-4.1-miniSlack APIGoogle SheetsGmail API

Key Features

Natural Language Input

No forms, no dropdowns. Just type like you're texting a friend: "καφές 3.50" or "βενζίνη 45€"

Multi-line Support

Log multiple expenses in one message. Each line becomes a separate record with unique tracking IDs.

Edit Support

Changed your mind? Edit the Slack message. The system detects modifications and updates records automatically.

Receipt Photos

Upload receipt images. GPT Vision extracts merchant name, amount, date, and payment method.

14+ Categories

Automatic categorization across house expenses, food, transportation, health, business, gifts, and more.

Monthly Reports

Automated HTML email reports with summaries, category breakdowns, and detailed expense lists.

Results

Metric Before After
Time to log expense 2-3 minutes 5 seconds
Missing expense records ~30% <2%
Monthly report preparation 2 hours Automated
Categorization accuracy Manual 95%+ AI-assisted
I just type 'καφές 3' and forget about it. At the end of the month, everything is there, organized, and ready for my accountant.

Technical Highlights

  • Concurrency protection: Lock file mechanism prevents duplicate processing
  • Bot filtering: System ignores its own messages to prevent loops
  • Error handling: Dedicated error workflow with Slack notifications
  • Full audit trail: Soft-delete functionality maintains complete history
  • Bilingual support: Processes Greek and English with equal accuracy
n8nSlackGPT-4Google SheetsExpense TrackingAI

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