Free online tools.
No sign-up. No uploads. No nonsense.

Every tool on ToolStack runs entirely in your browser — which means it's instant, works offline, and whatever you type never leaves your device.

Calculators

Percentage CalculatorFree online percentage calculator. Loan CalculatorFree loan payment calculator. BMI CalculatorFree BMI calculator with metric and imperial units. Age CalculatorFree age calculator. Tip CalculatorFree tip calculator. Discount CalculatorFree discount calculator.

Generators

Password GeneratorFree strong password generator. UUID GeneratorFree online UUID v4 / GUID generator. Lorem Ipsum GeneratorFree lorem ipsum generator. Random Number GeneratorFree random number generator. QR Code GeneratorFree QR code generator.

Converters

Unit ConverterFree online unit converter for length, weight, temperature, area, volume, speed and data storage. Color ConverterFree color converter. Text Case ConverterFree online case converter.

Text & Image

Word CounterFree word counter. Image CompressorFree image compressor that runs entirely in your browser.

Why ToolStack?

Truly privateCalculations happen on your device with plain JavaScript. No accounts, no cookies, no data collection — your inputs are never transmitted or stored.
Instantly fastNo frameworks, no pop-ups, no cookie banners. Pages weigh a few kilobytes and tools update live as you type, even on slow connections.
Free, foreverEvery tool is free with no usage limits, watermarks or expiring results. Bookmark what you use — it will still be here, working the same way.

What can you do here?

Quick answers to everyday math: work out a percentage, plan a loan payment or a restaurant tip, and check a BMI. Convert anything — units of measurement, color formats, text cases. Generate what you need: secure passwords, UUIDs, QR codes, random numbers or placeholder text. And work with text and images: count words or compress an image without uploading it anywhere.