MonsiTools is a calculator builder. You type a formula in plain words, for example price - product cost - shipping, and each word becomes an input field. The answer updates as you type, and you can save the result as your own calculator and share the link.
What you can do with it
- Build a calculator from a formula written in plain words, then save and share it.
- Use ready-made calculators for ecommerce fees, margins, VAT, SaaS metrics, loans, payroll and more.
- Chain calculators into workflows, so one result feeds the next step.
- Embed any calculator on your own site with a short snippet. The calculator resizes to fit the page.
- Call the calculators from an AI assistant through the MCP server, or from code through the API. Setup steps are on the developer page.
An example workflow
The homepage shows a SaaS runway and valuation chain. Step 1 works out monthly recurring revenue (320 customers at $49 is $15,680 MRR). Step 2 takes that revenue and a cash balance and returns months of runway. Step 3 turns yearly revenue into a rough valuation at a chosen multiple. Change the customer count in step 1 and every step after it updates.
Who it is for
Online sellers checking marketplace fees and margins, freelancers working out a day rate, SaaS founders tracking MRR and runway, and developers who want an assistant to run exact calculations instead of doing the math itself.
Pricing
No account is needed to start, there are no ads, and the numbers you type stay in your browser. Every tool has a limited free allowance (15 calculations without an account, 25 a month signed in). A paid Premium plan removes the limit and unlocks API and MCP calculation.
