Given a payment amount that fits in your budget, the interest rate you expect to receive, the length of the loan and the payment frequency (monthly, bi-weekly), AffordaBilly will tell you how much of a loan you can afford to take out. This can be extremely helpful for consumers shopping for mortgage loans, auto loans, or other large purchases, as it can give them an idea of what size loan they can afford to make the payments on.

FreePFM is a free, web-based personal finance manager written in Perl, using MySQL as a database. It features: multi-user support, user registration and session management, category-based, data export, and more.

SQL-Ledger is a multiuser accounting system written in perl. Data is stored in a SQL server (PostgreSQL or Oracle) and data entry and display is through a GUI or text based browser. Fully customizable with external code. The API may also be used to interface with other disparate systems. Features include: General Ledger, Accounts Receivable, Accounts Payable, Sales and Purchase Orders, Foreign Currency, Multiple Payments, Customizable Templates, Postscript and PDF output, Inventory Control, Chart of Accounts, Setup Utilities, and Administrator module.

This script will calculate sales tax. If you enter an all inclusive price, it will calculate how much your company takes and how much goes to the government. If you enter a price excluding tax, it will show you how much IVA is due. There is just one variable to configure which is the sales tax rate applicable in your country. All calculations are integerised.

VeryInteresting is a simple loan calculator. If a user enters a loan amount, an interest rate, the length of a loan, and the payment frequency, the calculator will show the monthly payment and the total interest that will be paid if the loan is paid to term. For monthly payments, it will also show an amortization table. This can be an exciting activity for students studying simple interest, as they can quickly change the number of years a loan is for or the interest rate and see the dramatic differences this makes in both the payment amount and the total amount paid in interest for a loan.

Given a payment amount, a loan or credit card balance, and an interest rate, PayBackTime will tell you how long it will take to pay off that loan or credit card, including the total interest you'll pay and total number of payments. This can be extremely interesting to consumers shopping for credit or a loan, as you can see how a small increase in payment or decrease in interest can shorten the payoff period. Calculates for both bi-weekly and monthly payments.