Manic Inventor Labs

Expense Matrix Splitter

Privacy-first group billing. 100% Local. No Accounts.

1. Participants

2. Transactions

Description Payer Amount Split Type

3. Data Management

💡 Tip: Since we don't store your data on servers, use the "Download Plan" button to save your work. You can upload it later or on a different device to continue!
Note: While data is saved in your browser automatically, it can be lost if you clear your cache. Downloading is the most reliable way to secure your plan.

How to Use the Expense Matrix

Step 1: Setup

Add the names of everyone involved in the trip or event. These will automatically populate as columns in your matrix.

Step 2: Log Expenses

Add a row for each bill. Enter a description (e.g., "Dinner"), select who paid, and enter the total amount.

Step 3: Define the Split
  • Eq (Equal): Simply uncheck boxes for anyone who shouldn't pay.
  • $ or %: Enter exact amounts or percentages for each person.
Step 4: Settle Up

Click "Calculate Everything" to see a total spending summary and the most efficient plan to pay everyone back.

Why use this Expense Splitter?

Most bill-splitting apps require everyone in your group to download an app and create an account. The Manic Inventor Expense Matrix is designed for speed and privacy. Whether you are planning a group trip, sharing a dinner, or managing roommate expenses, you can calculate who owes whom without any technical friction.

A Privacy-First Splitwise Alternative

We believe your financial habits shouldn't be stored on a server. This tool uses Local Storage technology, meaning all your transaction data stays in your browser. No data is ever sent to a database, and no signup is required. It is a completely anonymous way to settle debts.

Advanced Custom Split Logic

Unlike simple calculators, our matrix supports Fixed Amount ($) and Percentage (%) splits. If one person ordered a more expensive meal or a couple is sharing a room, you can switch from an equal split to a custom one with a single click. The tool validates your math in real-time to ensure the total always balances.

How the Exclusion Matrix Works

Our unique visual matrix allows for complex exclusions. If someone skipped a group activity or didn't share in a specific cost, simply uncheck their box. The settlement algorithm instantly redistributes the cost among the remaining participants, making it the most efficient way to handle "everyone-but-Alex" scenarios.