edgar-diff

Compare SEC filings side-by-side. See exactly what changed.

edgar-diff pulls full-text filings from the SEC EDGAR database and produces structured, section-by-section diffs — turning hours of manual comparison into seconds.

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Note

This project was built entirely by AI. Every line of code, every test, and every piece of documentation was written using AI tools (Claude) through an intentional vibe-engineering process. This was a targeted experiment in building a small, useful piece of software using AI tools exclusively — learning what works, what doesn't, and how to direct AI effectively for real engineering output. A detailed write-up of the process is forthcoming.

Warning

This project is not actively maintained. It was built as a learning experiment. You are welcome to use it, fork it, and build on it, but don't expect ongoing updates or support.

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What It Does

• ↔️ Side-by-side diff view — Additions, deletions, and modifications highlighted inline, organized by filing section (Risk Factors, MD&A, Financial Statements, etc.)
• 🗂️ Structured parsing — Filings are parsed into semantic sections, not treated as raw text blobs. A renamed section won't show up as a full delete + add.
• 📡 Direct EDGAR integration — Pulls filings straight from SEC EDGAR. No third-party data dependency.
• 📦 Reusable diff library — The core engine (@edgar-diff/lib) is decoupled from the UI and can be embedded in pipelines, monitors, or other tools.

Project Structure

edgar-diff/
├── apps/web/          # React web application (Vite + Cloudflare Workers)
├── libs/edgar-diff-lib/  # Core library: EDGAR client, filing parser, diff engine
├── scripts/           # Dev utilities (filing analysis, fetching)
└── docs/              # Setup guides and development docs

Monorepo managed with pnpm workspaces and Nx for task orchestration.

Tech Stack

• Runtime: Node.js >= 20
• Package Manager: pnpm (via corepack)
• Build/Task Runner: Nx
• Language: TypeScript
• Web App: React 19, Vite, Tailwind CSS, Cloudflare Workers
• Testing: Vitest, Testing Library, fast-check (property-based)
• Core Lib: htmlparser2, diff, jaro-winkler (section matching)

Getting Started

Prerequisites

• Node.js >= 20
• Git

Setup

# Clone the repo
git clone https://github.com/galexy/edgar-diff.git
cd edgar-diff

# Enable corepack (provides pnpm — do NOT install pnpm globally)
corepack enable

# Install dependencies
pnpm install

# Verify everything works
pnpm nx run-many --target=typecheck
pnpm nx run-many --target=test

Running the Web App

pnpm nx dev web

Once the dev server is running:

1. Open your browser at http://localhost:5173
2. Search for a company by name or ticker symbol (e.g. "AAPL" or "Apple")
3. Select two recent SEC filings to compare (e.g. two consecutive 10-K annual reports)
4. View the structured, section-by-section diff with additions, deletions, and modifications highlighted

Running Tests

# All tests (unit + integration + fixture-based e2e)
pnpm nx run-many --target=test

# Single project
pnpm nx test edgar-diff-lib

# Only affected projects (faster for incremental work)
pnpm nx affected --target=test

# Lint
pnpm nx run-many --target=lint

# Typecheck
pnpm nx run-many --target=typecheck

Common Issues

Problem	Fix
pnpm: command not found	Run corepack enable
pnpm version mismatch	Remove global pnpm: npm uninstall -g pnpm && corepack enable
nx: command not found	Use pnpm nx ... (Nx is a devDependency, not global)
Cannot find module after branch switch	pnpm install && pnpm nx reset

See docs/setup.md for more detailed troubleshooting.

License

This project is licensed under the MIT License.