Free tools that do one job well
Toolantern is a growing set of calculators, estimators and checkers. Each one does a single job, loads instantly and runs entirely in your browser, so nothing you type is uploaded. Pick a tool below.
All tools
AI & API costs
Why Toolantern
Most online calculators bury the answer under sign-up walls, pop-ups and vague numbers. Every Toolantern tool shows its working instead. You get the formula, a worked example and an honest list of what the tool does not account for, so you can trust the result or adjust it. Tools that depend on prices, such as AI model rates, carry the date their data was last checked.
New tools are added regularly. If there is a calculation you keep doing by hand, tell us about it.
Frequently asked questions
Are Toolantern tools really free?
Yes. Every tool is free to use with no account. The site is supported by advertising.
Is my data private?
Calculations run in JavaScript on your own device. What you type into a tool is not sent to our servers or stored. See the privacy policy for details on analytics and advertising cookies.
How current are the prices in the AI cost tools?
Each pricing tool shows the date its rates were last checked against the providers' official pricing pages. AI prices change often, so always confirm before committing to a budget.
Can I suggest a tool?
Please do. Use the contact page to describe the calculation you need and who it is for.