How to vibe codeFathom

Prerequisites

• Node.jsfree

  Runtime environment for Next.js and full-stack TypeScript execution.

• GitHubfree

  Source control and integration with Vercel deployment pipelines.

AI coding tools

• Claude Code

  Best-in-class agentic coding tool for scaffolding complex multi-file TypeScript logic and financial calculation engines.

• Cursor

  Ideal for fine-tuning complex charts, layout grids, and interactive financial reporting components.

Build guide

1. 01Project Scaffolding and Database Schema

   Initialize a Next.js project with TypeScript, Tailwind CSS, and Turso SQLite. Set up data models for companies, chart of accounts, monthly trial balances (P&L and Balance Sheet line items), and forecast scenarios.

   Create a Next.js 16 project with TypeScript and Tailwind CSS. Configure Drizzle ORM with Turso SQLite. Create database tables for: `companies` (id, name, currency), `accounts` (id, company_id, code, name, type [revenue, cogs, expense, asset, liability, equity]), `trial_balances` (id, company_id, account_id, period [YYYY-MM], debit, credit), and `forecast_scenarios` (id, company_id, name, assumptions_json). Set up better-auth for local single-user authentication. Verify the schema builds cleanly without errors.

   ⧉copy promptopen in Claude CodeCopen in Codexopen in Cursor

2. 02Trial Balance Ingestion and Financial Statement Engine

   Build CSV import parsers for trial balances and implement the core accounting engine that compiles raw lines into standard P&L, Balance Sheet, and Indirect Cash Flow statements.

   Build a CSV import utility using PapaParse that allows users to upload monthly trial balances (Account Code, Account Name, Type, Debit, Credit) for specific periods. Implement a server-side calculation engine that aggregates these rows into a standardized monthly Profit & Loss statement, Balance Sheet, and Indirect Cash Flow statement. Ensure the balance sheet equation (Assets = Liabilities + Equity) is validated on every period compile, throwing an explicit warning if out of balance. Create a dedicated API route and React dashboard view to inspect these compiled statements.

   ⧉copy promptopen in Claude CodeCopen in Codexopen in Cursor

3. 03KPI & Financial Analysis Module

   Implement calculation modules for 50+ financial and non-financial metrics, including gross margin, net profit margin, current ratio, break-even point, and working capital ratios.

   Implement a financial metrics calculation library in TypeScript that computes key performance indicators (KPIs) from the compiled P&L and Balance Sheet data: Gross Profit Margin, Net Profit Margin, Operating Cash Flow, Current Ratio, Quick Ratio, Days Sales Outstanding (DSO), and Break-Even Point. Build a responsive financial analysis dashboard using Recharts to visualize these KPIs over time alongside a cash flow waterfall chart showing cash inflows and outflows.

   ⧉copy promptopen in Claude CodeCopen in Codexopen in Cursor

4. 043-Way Cash Flow Forecasting Engine

   Build a projection engine that models future P&L, Balance Sheet, and Cash Flow statements up to 60 months out based on growth rate assumptions and driver rules.

   Build a 3-way cash flow forecasting engine in TypeScript. Allow users to configure growth rate assumptions for revenue, cost of goods sold percentages, accounts receivable collection days (DSO), accounts payable days (DPO), and capital expenditure schedules. The engine must project future monthly P&L, Balance Sheet, and Cash Flow statements simultaneously for up to 60 months, ensuring that cash balances roll forward correctly from the cash flow statement into the balance sheet cash asset account while maintaining the accounting equality.

   ⧉copy promptopen in Claude CodeCopen in Codexopen in Cursor

5. 05Management Reporting Builder

   Create a flexible layout editor allowing users to assemble narrative sections, summary KPI cards, and financial statements into brandable management reports.

   Build a drag-and-drop management reporting editor in Next.js. Allow users to create a custom report by adding modular blocks: Title blocks, KPI summary cards, P&L tables, Balance Sheet tables, and Recharts graph widgets. Implement a clean print and PDF export stylesheet using Tailwind print classes so reports can be exported or printed cleanly.

   ⧉copy promptopen in Claude CodeCopen in Codexopen in Cursor

6. 06AI Commentary Writer & Symbolic Attribution

   Integrate the Anthropic API to generate context-aware financial commentary with symbolic attribution that traces figures back to their underlying source accounts.

   Integrate the Anthropic API (Claude Sonnet) to build an AI Commentary Writer feature. Pass the selected report components (P&L summary, KPIs, variances) along with company business context (goals, strategy) into the prompt. Instruct the LLM to output structured JSON containing commentary paragraphs and explicit attribution metadata mapping numerical substrings back to specific source line items and periods. On the frontend, render these attributed figures with a distinct highlight style and a hover tooltip showing the exact source calculation formula or ledger component.

   ⧉copy promptopen in Claude CodeCopen in Codexopen in Cursor

Cost vs paying for Fathom