Put your Excel loan calculator on your website or app.
WorkbookAPI checks your Excel loan model in the browser for free, with calculator APIs and web forms for your website or app planned for early access. Customers need to change inputs and see a payment.
Check your workbook — free, it never leaves your browser
A working workbook is still a manual calculator.
A small lender may use Excel to calculate payments, lease terms, or equipment financing. A developer needs those results in an application. Sending a spreadsheet asks customers to use Excel and find the right cells.
Why the usual options hurt
Rewriting the formulas means keeping fees, rounding, and payment timing in sync. Running Excel on a server adds maintenance. Calculating every request by hand slows replies.
How it works with WorkbookAPI
Drop your loan or lease workbook into the free browser check. See which formulas compute exactly like Excel.
Recalculate and save in Excel first. The report compares results for those inputs; it does not validate every possible loan.
Today, only the browser check is live. Calculator APIs and web forms are planned for early access. Join the waitlist on the home page.
The planned API will return model outputs to your website or app. The model owner keeps editing Excel. Updating the workbook will update the payment calculation.
Illustration: a fixed-rate equipment loan
Assume monthly payments at the end of each month, with no fees.
- Inputs: $25,000 principal, 8% annual interest, and a 60-month term.
- Outputs: A monthly payment of $506.91, rounded to cents.
This is an illustrative calculation, not a lending offer. Your workbook defines its own rates, fees, and payment rules.
What is not supported
Macros/VBA, Power Query, pivot tables, what-if data tables, and links to other workbooks are not supported. Strict Open XML files are also unsupported. The report flags them.
FAQ
Can I embed my Excel loan calculator on a website?
An embeddable web form is planned.
Can my app use an Excel financing calculator through an API?
That is the planned API workflow: send the inputs and receive calculated outputs.
Will the check confirm every payment matches Excel?
The check compares formula results with saved Excel results for the current inputs. A match does not cover other terms, fees, dates, or input combinations.
Does my loan workbook leave my browser during the check?
No. The workbook never leaves your browser during the check. Only anonymous totals are counted, never values, formulas, or file names.
Read the privacy policy.
Start with your workbook
Check your workbook — free, it never leaves your browser
For an embedded form, see Excel web calculators. For code access, see Excel to API.