| What it does | Free online calculators, converters, and developer tools that run in your browser
| Date, deadline and time calculators with visible assumptions and sources
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| Stage | Startup
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| Founded | 2025
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| Based in | Not given
| US
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| Pricing model | Free
| Free
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| Pricing | Not given
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| Key features | - 68 free tools across finance, development, and utilities
- Loan repayment and affordability calculators with total interest calculations
- Currency converter with 30 world currencies and live exchange rates
- JSON formatter, validator, and minifier with syntax highlighting
- Date and time tools including age calculator and timezone converter
- Runs entirely in browser with no server uploads
- Works offline after initial page load
| - 184 calculators across 53 categories
- Shows counting rules and assumptions with each result
- Local-first processing with no data sent to servers
- Holiday and weekend calendar selection
- Business day counting
- Date arithmetic (add or subtract days, weeks, months, years)
- Sleep cycle planner with NIH-based 80-100 minute cycles
- Time zone conversion with DST handling
- Save results as images or add to calendar
- Schengen visa 90/180 day rolling window auditing
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| What makes it different | - No account or sign-up required
- Runs entirely client-side in your browser with no data sent to servers
- All tools are completely free with no usage limits
- Works offline after initial page load
- Privacy-first approach with no data collection or transmission
| - Shows the source and counting rule beside every answer
- No sign-up or account required to use any calculator
- All inputs stay in your browser for privacy
- Comprehensive coverage across 53 life and work categories
- Higher-risk calculators include prompts to verify with professionals
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| Community votes | 0 | 0 |
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| DR (Domain Rating by Ahrefs) | 4 ● no change since last check | Not checked yet ● no change since last check |
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| Trust Flow (Majestic) | 3 | 0 |
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| Citation Flow (Majestic) | 35 | 0 |
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| Referring domains (Majestic) | 6 | 0 |
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PlayTools
CalcSpan