Oak Ledger

Hassle-Free Invoice Generator

A fast, private, offline-first invoice app that lives on your device. No sign-ups. No subscriptions. Just invoices.

Open the App
01

Use only what you need

Every single field in Oak Ledger is optional. If something isn't relevant to your invoice—a client address, work dates, notes—just skip it. The invoice adapts to include only what you fill in, so you're never wrestling with blank fields or placeholder text.

How it works
  • Leave any field empty and it won't appear on the PDF or the preview.
  • The layout adjusts automatically—no awkward gaps or "N/A" placeholders.
  • Need a simple invoice with just a client name and an amount? That's all you need to fill in.
  • Running a detailed job with work periods, line-item services, and payment terms? Every field is there when you need it.
02

Works offline, installs like an app

Oak Ledger is a Progressive Web App. Visit it once and it caches everything you need to run offline—at a job site, on a plane, or when your connection drops. You don't even need to install it: just revisit the same URL in your browser without internet and it loads from cache. For the best experience, save it to your home screen and it launches full-screen, just like a native app.

  1. Open Oak Ledger in Chrome.
  2. Tap the ⋮ menu (three dots, top-right).
  3. Tap Install app or Add to Home screen.
  4. Tap Install to confirm. The icon appears in your app drawer and home screen.
  5. Open it anytime—it works without an internet connection.
  1. Open Oak Ledger in Safari (required—other iOS browsers won't work for this).
  2. Tap the Share button (the square with an upward arrow, bottom of screen).
  3. Scroll down and tap Add to Home Screen.
  4. Confirm the name and tap Add.
  5. Open it from your home screen—it runs full-screen and works offline.
  1. Open Oak Ledger in Chrome, Edge, or another Chromium browser.
  2. Look for the Install icon in the address bar (a small monitor with a down arrow), or check the browser menu.
  3. Click Install Oak Ledger.
  4. The app opens in its own window and appears in your desktop apps or start menu.
03

Professional PDFs in one tap

Hit Create PDF and a clean, formatted invoice downloads to your device immediately. The PDF includes your letterhead, business details, services breakdown, totals, and payment terms—ready to email or print.

Details
  • PDFs are generated entirely on-device using jsPDF—nothing is sent to a server.
  • The file name is generated automatically from the client name and date.
  • Preview your invoice before downloading to check layout and content.
  • The invoice number auto-increments after each PDF is created.
04

Business profiles & letterhead

Save your business name, contact info, and address once—they're remembered across invoices. Run multiple businesses or freelance under different names? Switch between up to four profiles with a single tap. Each profile keeps its own letterhead and invoice number sequence.

How to use
  • Fill in your business details under Your Business Details—they auto-save when you leave each field.
  • Tap the + button to add a new profile (up to 4). Switch between them using the tabs.
  • Upload a letterhead image (PNG, JPG, or SVG, up to 2 MB) in the header area. It appears at the top of every PDF.
  • To remove a letterhead, tap the image and then tap the × that appears.
05

Automatic invoice numbering

Each business profile maintains its own invoice number sequence. After every PDF you create, the number increments automatically. Need to use a specific number instead? Just type it in and Oak Ledger will continue from there.

How it works
  • The placeholder shows the next number in sequence (e.g. INV-004).
  • Leave the field blank to use the auto-generated number.
  • Type any number (e.g. 25 or INV-025) to override it. The sequence continues from your custom number.
  • Each profile tracks its own sequence independently.
06

Invoice history & CSV export

Every invoice you generate is automatically recorded. The history section shows a summary table of all past invoices at a glance. When you need to reconcile, file taxes, or hand records to your accountant, download everything as a CSV.

How to use
  • The Invoice History card appears automatically after your first invoice.
  • Tap the header to expand it and see a table of all invoices (newest first).
  • Tap Download CSV to export all recorded invoices with every field: invoice number, dates, client, services, amount, notes, and more.
  • Use Clear to remove all history if you need a fresh start.
07

LLM-assisted import

Have unstructured invoice details—an email, a text message, scribbled notes? Paste them in, copy a pre-built prompt for your favourite AI, and get back structured JSON that Oak Ledger can import in one click. The invoice populates itself and a PDF is generated immediately.

Step by step
  • Tap Import in the top-right to enter import mode.
  • Paste your raw invoice details into the LLM Assistant text box.
  • Tap Copy LLM Prompt to get a formatted prompt on your clipboard.
  • Paste the prompt into ChatGPT, Claude, or any LLM. It returns clean JSON.
  • Paste the JSON into the Import Invoice Data box and tap Import & Generate PDF.

Your invoices are private

Your data lives on your device

All your invoice data—business profiles, letterheads, invoice history—is stored in your browser's local storage. Your invoices are private and never transmitted to any server. Clear your browser data and it's gone.