Text & writing
Word Counter
Count words, characters, sentences and reading time.
Free online utilities
Free online developer tools.
Straightforward tools that work right here on your phone, tablet or computer. No account, no AI, no nonsense.
Your tool data stays on this device.
Anything you type, paste, calculate or open in a tool is not sent to us. KitLumo does not receive it or save a copy.
KitLumo Developer tools
Free Developer Tools for everyday tasks
Free browser-based developer tools for JSON, URLs, hashes, encodings, timestamps and everyday coding tasks. Choose a focused tool below and get an answer without creating an account.
Every listed tool is designed to run on the device you are using. KitLumo does not keep a copy of what you enter into a tool.
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76 tools
Text & writing
Case Converter
Switch text to uppercase, title case, sentence case and more.
Calculators
Markup Calculator
Calculate margin, markup, profit and a selling price.
Security
Password Generator
Create strong passwords locally, without saving them.
Developer
JSON Formatter
Format, validate or minify JSON in one place.
Images
Image Resizer
Resize JPG, PNG and WebP images on your own device.
New
Text & writing
Line Cleaner
Sort lines, remove duplicates and clean up pasted lists.
New
Calculators
Unit Converter
Convert common length, weight, volume and temperature units.
New
Developer
CSV to JSON
Turn comma-separated data into clean, copyable JSON.
New
Developer
Base64 Converter
Encode or decode text without sending it anywhere.
New
Design
Colour Converter
Switch between HEX, RGB and HSL colour values.
New
Security
Random Number
Pick a secure random whole number in your chosen range.
New
Calculators
Loan Calculator
Estimate monthly repayments, total interest and total cost.
New
Calculators
Date Difference
See the time between two dates in days and weeks.
New
Developer
URL Encoder
Encode or decode URL text safely in your browser.
New
Security
Hash Generator
Create SHA-256 or SHA-512 hashes locally.
New
Developer
UUID Generator
Generate random UUIDs for software and data work.
New
Text & writing
Slug Generator
Turn titles into clean URL-friendly slugs in seconds.
New
Calculators
Percentage Calculator
Calculate a percentage, share, or percentage increase.
New
Developer
Timestamp Converter
Convert Unix timestamps to readable dates and back.
New
Text & writing
Text Diff
Compare two texts line-by-line and spot every change.
New
Developer
JWT Decoder
Inspect a token’s header and payload locally. No verification.
New
Developer
JSON to CSV
Turn a JSON array into a tidy, spreadsheet-ready CSV file.
New
Developer
URL Parser
Break a URL into its host, path, query values and more.
New
Developer
HTML Entities
Encode or decode HTML entities without sending text anywhere.
New
Design
Contrast Checker
Check contrast ratios and text readability against WCAG levels.
New
Text & writing
Lorem Ipsum
Generate placeholder paragraphs, sentences or words for layouts.
New
Calculators
VAT Calculator
Add VAT to a price or extract it from a VAT-inclusive total.
New
Calculators
Discount Calculator
See the sale price, amount saved and optional tax in one view.
New
Calculators
Tip Splitter
Split a bill and tip fairly across any number of people.
New
Design
Aspect Ratio
Scale image or video dimensions without changing proportions.
New
Developer
Number Base Converter
Convert integers between binary, octal, decimal and hexadecimal.
New
Security
File Checksum
Create a SHA checksum for a local file to verify its integrity.
New
Images
Image Compressor
Reduce JPG or WebP file size locally with a quality control.
New
Developer
Regex Tester
Test a regular expression and inspect every match safely.
New
Calculators
Compound Interest
Estimate investment growth with recurring contributions.
New
Calculators
Business Days
Count weekdays between dates and exclude your own holidays.
New
Calculators
Age Calculator
Calculate an exact age in years, months and days.
New
Calculators
Fuel Cost
Estimate fuel needed and the cost of a one-way or return trip.
New
Calculators
Time Duration
Find the time between two dates and subtract a break.
New
Developer
Data Size Converter
Convert between bytes, KB, MB, GB and their binary equivalents.
New
Calculators
Mortgage Calculator
Estimate monthly home-loan payments, interest and total repayment.
New
Calculators
Salary Converter
Convert annual pay into monthly, weekly, daily and hourly amounts.
New
Calculators
Average Calculator
Find the mean, median, sum and range of a list of numbers.
New
Calculators
Ratio Calculator
Simplify a ratio and compare each value as a share of the whole.
New
Calculators
Pace Calculator
Calculate running pace, speed and equivalent pace per mile.
New
Text & writing
Text Reverser
Reverse characters, word order or line order instantly.
New
Text & writing
Morse Code Translator
Translate text to Morse code or decode dots and dashes.
New
Developer
CSS Clamp Calculator
Build a responsive CSS clamp value for fluid sizes.
New
Calculators
Electricity Cost
Estimate what an appliance costs to run per day or period.
New
Calculators
Break-even Calculator
Find how many units you must sell to cover your costs.
New
Security
Password Strength Checker
Check password length and variety without sending it anywhere.
New
Developer
JSON Key Sorter
Sort object keys recursively for stable, readable JSON.
New
Text & writing
List Randomizer
Shuffle a list and pick one or more items at random.
New
Security
Unix Permissions
Build a chmod value from clear read, write and execute controls.
New
Calculators
Scientific Calculator
Do everyday and advanced maths directly in your browser.
New
Calculators
BMI Calculator
Estimate body mass index from adult height and weight.
New
Calculators
GPA Calculator
Work out an unweighted 4.0 grade-point average.
New
Text & writing
Number to Words
Spell a whole number out in plain English.
New
Calculators
Time Zone Converter
Convert a date and time between major cities worldwide.
New
Security
Credit Card Validator
Run a local checksum check without submitting a card number.
New
Calculators
Online Timer
Set a simple countdown timer for any task.
New
Calculators
Online Stopwatch
Track elapsed time with start, pause and reset.
New
Developer
Image to Base64
Convert a local image to a data URL without uploading it.
New
Calculators
Calorie Calculator
Estimate adult daily calorie needs using your activity level.
New
Calculators
Sales Tax Calculator
Add a local sales-tax, VAT or GST rate to a price.
New
Calculators
Overtime Pay Calculator
Estimate gross regular and overtime pay for a work week.
New
Calculators
Retirement Calculator
See how savings and monthly contributions could grow over time.
New
Calculators
Grade Calculator
Work out a weighted class grade from scores and assignments.
New
Calculators
Debt Payoff Calculator
Estimate how long a fixed monthly payment takes to clear debt.
New
Calculators
Fraction Calculator
Add, subtract, multiply or divide and simplify two fractions.
New
Calculators
Square Footage Calculator
Find area for rooms, floors, gardens and projects in any unit.
New
Calculators
Savings Goal Calculator
Estimate how long it could take to reach a savings target.
New
Calculators
ROI Calculator
Calculate profit, return on investment and investment multiple.
New
Calculators
Debt-to-Income Calculator
Compare monthly debt payments with gross monthly income.
New
Calculators
Fuel Economy Converter
Convert L/100 km, US MPG, UK MPG and kilometres per litre.
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How KitLumo stays free
Supported by ads. Helped by people.
Clearly labelled ads fund the website so everyone can use every tool for free. If KitLumo saves you time, you are also welcome to make an optional donation to help pay for hosting and keep the tools available.
Donating never unlocks extra features. Every tool remains free for everyone.How it works
Free means free.
KitLumo is built around small, focused utilities. No login walls, no artificial limits and no AI layer where a reliable tool will do.
Every tool currently available works directly on the phone, tablet or computer you are using. Anything you type, paste, calculate or open in a tool is not sent to us, and KitLumo does not save a copy.
Your saved and recently used tool shortcuts are stored only in your browser on this device. When you use “Report a problem” or “Request a free tool,” only that message and any email address you choose to add are sent to KitLumo.