MasterKit Online is a collection of 63 free online tools and calculators. We build each tool to solve one job well, explain how it works, and show the sources behind every formula.
Why we built it
Many free tool sites give you a number with no explanation, use outdated tax rates or bury the tool under ads. We wanted the opposite: fast tools that show their working, run privately in your browser and stay accurate when rules change.
How we check accuracy
- Official sources first. Tax tools follow the IRS, HMRC and the Income Tax Department of India, education tools follow published grading rules such as CBSE's, and health tools use published formulas such as Mifflin-St Jeor and WHO BMI categories.
- Worked examples. Every tool page includes worked examples that we verify by hand.
- Regular reviews. Each page shows a "last updated" date. We re-check tax tools after every US tax-year update, UK Budget and Indian Union Budget.
Privacy
Calculators, text tools and image tools run in your browser. We do not upload your numbers, text or photos. Read our privacy policy for details.
Our categories
- Math Tools (8 tools)
- Education Tools (7 tools)
- Finance Calculators (16 tools)
- Health Calculators (7 tools)
- Date & Time Tools (3 tools)
- Text Tools (6 tools)
- Developer Tools (7 tools)
- Image Tools (4 tools)
- SEO & YouTube Tools (4 tools)
- Unit Converters (1 tools)
Contact
Found a mistake or want a new tool? Email hello@masterkitonline.com or use the contact page.