MyHandyKit —— everyday tools

A growing set of 161 browser-based tools with examples you can try instantly — percentages, dates, unit conversion, word counts, JSON and timestamps. Everything runs locally in your browser, results appear as you type, and nothing is uploaded. If a result puzzles you, ask the built-in AI to explain it step by step.

Popular

These tools are provided for general reference only. For tax, legal, medical or financial decisions, please rely on official sources or a qualified professional.

Understand
Ask AI about any result, right next to it
Ask away
Follow-up questions until it makes sense
Find it
Math, dates, text and developer tools in one place
Keep it free
No limits, no sign-up, free to use
Take it away
One click to copy the result
Anywhere
Phone, tablet or desktop — just open it

Math Percentages, averages, powers, roots and other everyday math.

Circle Calculator Radius, diameter, circumference, area Complex Number Calculator Arithmetic, modulus and argument Discount Calculator Percent-off, tiered savings and deal comparison in one place Fraction Calculator Exact fraction arithmetic GCF and LCM Calculator GCF and LCM for many numbers, with prime factors GPA Calculator 4.0 / 5.0 / percentage weighted GPA Linear System Solver Exact fractions · solution-type detection Log Calculator log base 10, e, 2 or any custom base Mean Calculator Mean, median, variance and SD in one pass Percentage Change Calculator Increase, decrease, reverse and CAGR in one place Percent Error Calculator How far a measurement is off, in % Percentage Calculator Find X% of Y, what percent X is of Y, and percent change Permutation & Combination Calculator Exact nCr and nPr Exponent & Root Calculator Powers, square roots, cube roots and nth roots Pythagorean Theorem Calculator Find the third side of a right triangle Quadratic Equation Solver Discriminant, exact roots, Vieta Ratio Calculator Solve A:B = C:x, simplify ratios, get percentages Remainder Calculator Quotient, remainder and the check Scientific Calculator Trig, logs and powers with live results Scientific Notation Calculator Convert to a × 10ⁿ and calculate Standard Deviation Calculator Spread of a data set, two conventions Triangle Calculator Area and angles from three sides Trigonometry Calculator sin, cos, tan and inverse functions in deg or rad Weighted Average Calculator Weighted average from any weights

Text Word counts, case conversion, diff and text cleanup.

Case Converter 11 text case styles in one click Full-width / Half-width Converter Convert full-width characters both ways, fix text pasted from PDF HTML Entity Encoder Escape for safety · encode for portability HTML to Markdown Converter Headings, lists, tables and links converted to Markdown List Dedupe & Sort Dedupe, sort, count — one paste Lorem Ipsum Generator Paragraphs, sentences or words — filler text for layouts Markdown Word Counter Text stats + structure counts Markdown Table Generator Table data and Markdown both ways Morse Code Converter Text to Morse and back, with a 54-entry chart Online Notepad Auto-saved in your browser, no signup needed Strip HTML Tags (Extract Plain Text) Turn HTML source into plain text, dropping scripts and styles Text Diff Line-by-line differences and similarity Word Counter Count characters, words, sentences and paragraphs in real time Word Frequency Counter Characters, words, 2-grams and 3-grams with counts and percentages Zero-Width Character Remover Find and remove invisible characters that break text

Date & Time Date differences, age, workdays and time conversion.

Age Calculator Exact age in years, months and days with next birthday countdown Countdown Calculator Time remaining, down to the second Countdown Timer Set a duration, count down to zero Date Calculator Days between dates, plus add or subtract days Day Counter Live totals · milestone countdowns Leap Year Calculator Leap year check for any year or range Online Clock A big, always-on web clock Pomodoro Timer 25 minutes focus + 5 minutes break, on repeat Online Stopwatch Lap times, fastest and slowest flagged Time Calculator Add, subtract and sum times Timestamp Converter Convert Unix timestamps to dates and back, auto-detecting units Time Zone Converter Cross-zone time with DST Week Number Calculator (ISO 8601) ISO week and dates both ways Work Hours Calculator Hours worked and overtime pay

Conversion Length, weight, temperature, area and other unit conversions.

Angle Converter Degrees, radians, gradians, turns Area Converter Mu, fen, hectares and square meters in one place Data Size Converter Decimal GB and binary GiB side by side Energy Converter J, kJ, cal, kcal, Wh, kWh Force Converter N, kN, kgf and lbf Frequency Converter Hz, kHz, MHz, GHz and rpm Fuel Economy Converter L/100km, km/L, mpg conversions Length Converter Convert between metric, imperial and nautical units Power Converter W, kW, MW, PS and hp Pressure Converter Tire pressure, blood pressure, engineering Roman Numerals Converter Two-way conversion from 1 to 3999 Shoe Size Converter Foot length and shoe sizes Speed Converter Road, science, nautical and Mach speeds in one place Temperature Converter Celsius, Fahrenheit and Kelvin conversions with formulas Time Converter Seconds to years, with stated conventions Torque Converter N·m, kgf·m and lbf·ft Volume Converter Liters, gallons, cups and cubic units in one place Weight Converter Metric, Chinese jin/liang and imperial units side by side

Developer JSON, timestamps, hashes and other developer helpers.

ASCII Table Look up any character's code in four number bases Bar Chart Maker Two columns of text, one click to chart Base Converter Convert between any bases from 2 to 36, with BigInt precision Color Converter HEX / RGB / HSL conversion Cron Expression Parser Field-by-field reading · Next 5 runs CSV and JSON Converter CSV and JSON both ways Encoding Converter Convert text to Base64, HEX and binary, UTF-8 safe Fake Data Generator Chinese names · Masked phones · Valid checksums JSON Formatter Beautify, minify and validate JSON instantly Line Chart Maker Time series at a glance Markdown to HTML Source + preview · XSS safe Pie Chart Maker Shares of a whole, clockwise from 12 Regex Tester Live highlighting · Capture groups · Local SQL Formatter and Minifier Pretty-print or compact SQL IPv4 Subnet Calculator CIDR parsing · Host range · Private-IP check URL Encoder & Decoder Two modes · Query parsing · Strict errors URL Parser Every part of a URL, decoded UUID Generator Crypto-secure UUID v4 in bulk YAML and JSON Converter YAML and JSON both ways

Health & Life BMI, calories, sleep and everyday life calculators.

Bill Splitter Split evenly or by person Blood Alcohol Calculator Widmark-formula BAC estimate BMI Calculator Calculate your Body Mass Index with the Chinese standard BMR Calculator (BMR / TDEE) Three BMR formulas plus TDEE Body Fat Calculator Estimate body fat from BMI, age and sex Calorie Calculator BMR, TDEE and goal calories Calories Burned Calculator (MET) Estimate exercise calories by MET Child Growth Velocity Calculator How much growth per year is normal Child Height Calculator Mid-parental height prediction Conception Date Calculator Estimate the conception window Gas vs Electric Car Cost Energy-only comparison, transparent math Heart Rate Zone Calculator Max heart rate and five zones Ideal Weight Calculator Four formulas, one healthy range Mortgage Calculator Compare annuity and linear mortgage payments instantly Online Metronome Dial in a tempo, keep the beat Online Ruler Calibrate with a bank card, measure anything Ovulation Calculator Ovulation day and fertile window Pet Age Calculator Cat & dog years, converted the vet way Pregnancy Calculator Due date and week from LMP Protein Intake Calculator Daily protein target by body weight Random Picker Paste a list, draw fairly, verify with a seed Renovation Quantity Calculator Know exactly how much material to buy Running Pace Calculator Pace, speed and marathon splits Safe Period Calculator Period, fertile and safe days marked day by day Shift Work Calendar One anchor day, thirty days laid out Sleep Calculator 90-minute cycles and best times Typing Test Timer starts on your first keystroke Water Intake Calculator Daily water range from weight and exercise

Finance Loans, interest, savings and personal finance calculators.

Car Loan Calculator Monthly payment and real APR with fees Compound Interest Calculator Future value with monthly contributions Credit Card Installment Calculator The real APR behind installment fees Deposit Interest Calculator Lump-sum and monthly deposit interest FIRE Calculator Find your FIRE number and retirement age NPV & IRR Calculator NPV · IRR · payback · discount table Position Averaging Calculator Average cost and target-basis reverse Mortgage Prepayment Calculator Shorten term or reduce payment, with penalties Profit Margin Calculator Margin, markup and break-even point ROI Calculator Total and annualized return, simple or compound SIP Calculator Future value of regular investing

Security Passwords, hashes, encoding and crypto utilities.

AES Encrypt / Decrypt AES-CBC with a password, random salt and IV, computed locally Base32 Encoder / Decoder RFC 4648 both ways, with 8-character grouping, computed locally Base58 Encoder / Decoder Bitcoin alphabet both ways, leading zero bytes preserved Caesar Cipher / ROT13 Converter Shift 1-25 with ROT13, ROT47 and a 25-shift brute-force table CRC-32 Checksum Calculator 8-digit hex checksum, same algorithm as zip, gzip and PNG Sensitive Data Masker Client-side regex masking File Hash Checker MD5, SHA-1 and SHA-256 for local files, read in your browser HMAC Signature Generator SHA-256 / SHA-1 / MD5, hex and Base64 output, computed locally JWT Decoder Decode header/payload and check expiry locally MD5 Generator 32-digit digest, uppercase and 16-digit short form Password Generator Crypto-secure random passwords, generated locally Password Strength Checker Score, entropy and crack-time estimate Random Number Generator Range draws, shuffling and dice rolls from a crypto source SHA-256 Hash Generator Client-side SHA-256 hashing TOTP Code Generator RFC 6238 codes with countdown and next-code preview, computed locally Vigenere Cipher and Rail Fence Cipher Key-driven classical substitution plus rail fence

Files & Images Image and PDF tools that run entirely in your browser.

Image Compressor Adjust quality and size, download instantly — images never leave your browser Image Converter PNG, JPG and WebP conversion with transparency explained Image Cropper Ratio or free crop, rotate and flip - images never leave your browser EXIF Viewer & Remover See what your photos hide, then take away a clean copy Image Grid Cutter Slice a picture into tiles for seamless grid posts Image Merger Stitch screenshots and photos into one image Image Mosaic Pixelate before you post Image Resizer Proportional scaling by max side or percent, no distortion ICO Generator One PNG in, a multi-size favicon.ico out Image to PDF Bind photos into a PDF, order preserved Image Watermark Tile your handle across the image, locally PDF Merge Combine PDFs in order — files never leave your browser PDF Page Organizer Reorder, remove and rotate pages - one clean new PDF PDF Split Extract pages by range — original file stays untouched QR Code Generator Turn any text, URL or WiFi config into a scannable code Signature Generator Draw once, export a transparent PNG signature

No matching tool — try another keyword

FAQ

Do I need an account to use these tools?

No. There is no sign-up and no account system. Every tool works right away with no usage limits, and we do not collect personal details.

Is my input uploaded to a server?

No — by default everything is calculated in your browser, so your numbers and text never leave the page and the tools keep working offline. Data is only sent when you actively use the AI assistant or submit feedback; in those cases please do not include passwords, ID numbers or bank details.

Will these tools stay free?

Yes. The current tools are free with no usage limits, and adding new features will not turn them into paid ones. We do not sell software, licences or paid downloads.

Can I rely on the results as professional advice?

No. The tools implement public formulas and general conventions, so results are for reference only. For tax, loan, health or legal matters, always check an official source or a qualified professional.