How to vibe codeFreeAgent

Prerequisites

• Node.jsfree

  Runtime for building the full-stack TypeScript web application.

• GitHubfree

  Version control and CI/CD deployment pipeline.

• 

  HMRC Developer Accountfree

  Required for sandbox and production access to Making Tax Digital and PAYE APIs.

AI coding tools

• Claude Code

  Best-in-class multi-file agentic coding tool for scaffolding complex relational database schemas and backend logic.

• Cursor

  AI code editor for iterative frontend UI polish and accounting form components.

Build guide

1. 01Project Scaffolding and Database Schema

   Initialize the Next.js project with Tailwind CSS, configure Turso SQLite with Drizzle ORM, and set up better-auth for secure user authentication.

   Create a new Next.js project with TypeScript, Tailwind CSS, and App Router. Set up Drizzle ORM configured for Turso SQLite. Define the foundational database schema for multi-tenant accounting: users, organizations, accounts (chart of accounts with types like asset, liability, income, expense, equity), journal_entries, and journal_lines. Ensure the sum of debit and credit lines equals zero on every journal entry transaction via application-layer validation and database constraints. Integrate better-auth for secure email/password and session management with multi-tenant organization switching.

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2. 02Double-Entry Ledger & Chart of Accounts Engine

   Build the core accounting engine capable of recording balanced journal entries and generating trial balances and profit & loss statements.

   Build the double-entry bookkeeping ledger engine in Next.js server actions. Implement a robust transaction creation form where users can record bills, invoices, and manual journal entries. Write SQL aggregation queries and helper functions to dynamically generate a Trial Balance, Profit & Loss statement, and Balance Sheet for any selected fiscal year-end date range. Add unit tests verifying that unbalanced journal entries are rejected and account balances update accurately.

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3. 03Invoicing & Client Management Module

   Develop client management, itemized invoice creation, PDF rendering, and Stripe payment link integration.

   Create an invoicing module in Next.js. Build CRUD views for clients, billable items, and branded invoices with line-item tax calculations (including standard 20% VAT). Implement a server-side PDF generator using react-pdf to export professional invoice documents. Add Stripe Checkout integration so that paying an invoice automatically posts a balancing debit to bank/cash and credit to accounts receivable in the double-entry ledger.

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4. 04Expense Tracking & AI Smart Capture

   Implement expense recording and an AI-powered receipt scanning feature using OpenAI Vision API.

   Build an expense tracking interface supporting out-of-pocket expenses and bill uploads. Integrate the OpenAI API (or Anthropic API) to parse uploaded receipt images and extract vendor name, date, total amount, and VAT breakdown into structured JSON. Automatically map parsed data to the appropriate expense category in the chart of accounts and generate the corresponding journal entry.

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5. 05Open Banking Feed Simulator & Transaction Explanation

   Create bank account management, statement imports via CSV/OFX, and smart transaction explanation rules.

   Develop a bank accounts module allowing users to connect and view bank balances. Implement CSV and OFX statement import parsers to ingest bank feeds. Build a transaction explanation workflow where raw bank statement lines can be matched and explained against existing invoices, bills, or out-of-pocket expenses, automatically posting the clearing journal entries to the ledger.

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6. 06HMRC Making Tax Digital (MTD) Integration Stub

   Build the HMRC MTD OAuth authentication flow and quarterly VAT return calculation engine.

   Implement an HMRC Making Tax Digital (MTD) module. Set up the OAuth2 authorization code flow connecting to the HMRC Developer Hub sandbox environment. Build a VAT return calculator that queries ledger transactions for a 91-day taxable period, aggregates Box 1 through Box 9 figures according to UK VAT rules, and provides a structured JSON payload preview ready for submission to the HMRC VAT API.

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Cost vs paying for FreeAgent