81 free tools · nothing ever leaves your browser
Free online tools that just work
Calculators, converters, text utilities, developer helpers and generators — all in one fast, private place. No sign-up, no uploads, no clutter.
Most used tools
The ones people open again and again.
Age Calculator
Date & Time Tools
Calculate an exact age in years, months and days from a birth date, plus total days lived and the countdown to the next birthday.
Open toolBase64 Encoder & Decoder
Text Tools
Convert text to Base64 and back, with support for URL-safe Base64 output.
Open toolBMI Calculator
Calculators
Calculate Body Mass Index in metric or imperial units and see the healthy weight range for your height.
Open toolBorder Radius Generator
CSS Tools
Round each corner independently with live sliders and copy the ready-to-use CSS border-radius rule.
Open toolBox Shadow Generator
CSS Tools
Dial in offset, blur, spread and colour to design a CSS box-shadow and copy the finished rule.
Open toolCase Converter
Text Tools
Convert text to UPPERCASE, lowercase, Title Case, Sentence case, camelCase, snake_case and more.
Open toolColour Contrast Checker
Color Tools
Check the WCAG contrast ratio between a text colour and its background and see which levels pass.
Open toolCompound Interest Calculator
Calculators
Project how savings or investments grow over time with compounding and regular contributions.
Open toolBrowse by category
Eight categories covering everyday maths, writing, design and development.
Text Tools
Count, clean and transform text
14 toolsDeveloper Tools
Format, validate and decode
13 toolsCalculators
Everyday maths and money
12 toolsConverters
Units, data and measurements
10 toolsGenerators
Create data on demand
9 toolsCSS Tools
Visual CSS builders
10 toolsColor Tools
Pick, convert and check
6 toolsDate & Time Tools
Dates, ages and durations
7 toolsWhy use PlainToolbox?
Private by design
Nothing is uploaded. Every calculation happens locally in your browser, so even sensitive data stays on your machine.
Instantly fast
Pages are pre-rendered and tools run without a network round trip, so results appear the moment you finish typing.
No sign-up, ever
No accounts, no paywalls, no email capture. Open a tool, get your answer, move on with your day.
One consistent design
Every tool shares the same layout, keyboard shortcuts and copy buttons, so learning one means learning them all.
Every tool on the site
All 81 tools, grouped by what they do.