Small tools that just work.
A growing collection of fast, free utilities for freelancers, small businesses and everyday tasks. Everything runs right in your browser.
Browse all tools
VAT calculator
Add or remove VAT, get net and gross instantly.
newLoan calculator
Monthly payment, total interest and amortization.
newEmail signature generator
Clean HTML signature, ready to paste into any inbox.
Percentage calculator
Percent of, percent change, or reverse a percentage.
Case converter
camelCase, snake_case, kebab-case, PascalCase and more.
Color picker
Pick any color and copy its HEX, RGB and HSL codes.
JSON formatter
Format, validate and minify JSON instantly.
Unit converter
Length, weight, temperature, area, volume and speed.
hotInvoice generator
Create a professional invoice in seconds, no account.
newBreak-even calculator
Units and revenue needed to cover your fixed costs.
newFreelance tax estimator
Quarterly tax estimates for self-employed workers.
Profit margin calculator
Cost, price, markup and margin in one place.
Word counter
Words, characters, sentences and reading time.
newContrast checker
WCAG AA and AAA contrast ratio for any two colors.
newQR code generator
Turn any link or text into a scannable QR code.
Password generator
Strong, random, customizable passwords.
newFreelance hourly rate calculator
Find the minimum rate you need to charge as a freelancer.
newUpwork fee calculator
Estimate your take-home pay after Upwork's service fee.
newPayPal fee calculator
See what you'll receive after PayPal's Goods & Services or Friends & Family fees.
newStripe fee calculator
See what you'll receive after Stripe's processing fees and surcharges.
newPayroll cost calculator
Find the true cost of hiring someone, beyond just the salary.
newROI calculator
Return on investment, payback period and annualized ROI.
newQuote generator
Create a professional quote or estimate and download it as PDF.
newMarkup calculator
Selling price, profit and margin from cost and markup — single or multiple items.
In and out in seconds
Pick a tool
Browse the collection or search by name. Every tool is free and open — no account, no paywall.
Enter your data
Fill in your numbers, text or settings. Everything processes instantly in your browser — nothing is sent to a server.
Get your result
Copy, download or use the output directly. Done. No steps, no friction, no follow-up emails.
Frequently asked questions
Why Cloistr?
Most free tool sites bury the actual tool behind a sign-up wall, an ad-heavy layout, or a "free trial" that isn't really free. Cloistr doesn't do any of that — every tool is genuinely free, works instantly with no account, and runs entirely in your browser so nothing you enter is ever sent anywhere.
Are all tools really free?
Yes. Every tool on Cloistr is completely free to use. No premium tier, no credit card, no trial period.
Do I need to create an account?
No account, no registration, no email address. Just open a tool and use it.
Is my data safe?
All calculations happen directly in your browser. Your data is never sent to our servers.
Can I use these tools for commercial purposes?
Absolutely. Cloistr is designed for freelancers and small businesses. Use it for any purpose.
How often are new tools added?
New tools are added regularly, focused on what freelancers and small businesses actually need.
How can I suggest a new tool?
Email us at contact@cloistr.io. We read every suggestion.