シャラパン ChatteLapin

Products business

Operating base

business

AI-driven accounting automation — an operating foundation.

Fieldfreee × Claude Vision
StatusPhase 0 completed (2026-05-21)
PolicyDeveloped with OSS publication in mind

Positioning.

business is ChatteLapin's operating foundation. It is not sold as a product; it is a mechanism to minimize the operational hours of running the business. It implements the mission "Place a quiet hour between technology and the analog" in the realm of accounting — perhaps the one that most aggressively steals time and attention.

The motivation for choosing sole proprietorship was itself "much of accounting looks automatable with AI." By building the automation foundation in-house, the proprietor's own time is redirected toward product development and creative work.

With future open-sourcing in mind, the project is maintained as an implementation record that can serve as a reference for sole proprietors and developers in a similar position.

Three-layer pipeline.

  1. 01

    Automatic ingestion from banks / cards

    Transactions from the trade-name bank account and various cards are pulled in via freee's auto-sync; a rules engine maps each description to an account item. A confidence threshold splits "auto-confirm" from "awaits review".

  2. 02

    Reweaving paper receipts with AI

    Paper receipts photographed on a smartphone arrive via Discord → Claude Vision (= a multimodal LLM) performs OCR and account-item inference in a single shot → the freee API registers the journal entry and attaches the image (= compliant with Japan's e-Document Preservation Act). The certainty of analog paper is bridged into the digital ledger.

  3. 03

    Monthly automatic checks / reports

    Balance reconciliation, anomaly detection, automatic generation and delivery of a monthly P&L PDF. A tax-saving scheme simulation is also integrated, minimizing the aggregation cost at tax-filing time.

Development status.

Phase 0 scaffolding was completed on 2026-05-21. App registration on the freee developer portal, implementation of the OAuth 2.0 authorization flow, and a working connection to the transactions API have all been reached.

Phase 1 (= rules engine + home-business allocation + tax-saving simulation) will start once the trade-name bank account is opened. Phase 2 (= Discord Bot + Claude Vision receipt OCR) follows the stabilization of Phase 1.

Technical stack.

  • TypeScript + tsx (= no build step)
  • freee Accounting API (= OAuth 2.0)
  • Anthropic Claude Vision (= Claude 4.x / multimodal)
  • discord.js (= Bot intake channel)
  • zod (= API response validation)

Related links.