Calculators & converters
Square Footage Calculator
thesquarefootagecalculator.comWork out the area of rooms, floors, walls and land in square feet or meters, with support for rectangles, L-shapes, circles and triangles. Handy for flooring, paint and tiling estimates, it also converts between area units so quotes and material orders come out right.
Percentage Calculator
bestpercentagecalculator.netEvery percentage problem in one place: what is X% of Y, percentage increase and decrease, percentage difference, discounts and tips. Each mode explains the formula it used, so you learn the math instead of just copying the answer.
Age Calculator
theagecalculator.netCalculate exact age in years, months, weeks and days from any date of birth, count down to the next birthday, or measure the precise gap between two dates. Useful for forms, eligibility cut-offs and settling family arguments.
Hours Calculator
calculatehours.netAdd up hours and minutes between clock-in and clock-out times, across breaks and overnight shifts. Built for timesheets, payroll checks and freelancers billing by the hour, with decimal-hours output for invoicing.
Box Volume Calculator
boxvolumecalculator.comVolume and capacity for boxes, cartons and containers in cubic inches, feet, centimeters and liters. Helps with packaging selection, storage planning and figuring out whether an order actually fits the box.
Girth Calculator
girthcalculator.comPackage girth (length + 2×width + 2×height) against the size limits of USPS, UPS, FedEx and other carriers, so oversize surcharges don't surprise you. A separate fitness section covers body circumference measurements.
Dimensional Weight Calculator
dimweightcalc.comBillable weight across 17 shipping carriers: enter package dimensions and the calculator applies each carrier's DIM divisor to show whether you'll be charged actual or dimensional weight. Essential for e-commerce shipping costs.
Margin vs Markup
marginvsmarkup.comThe pricing calculator that keeps margin and markup straight — two numbers that get confused in real businesses every day. Convert between them, work back from a target margin to a selling price, and see the formulas behind each answer.
EMI Calculator
indiaemi.comMonthly EMIs for home, car and personal loans in India, with full amortization schedules showing how each payment splits between principal and interest. Compare tenures and prepayment scenarios before signing anything.
Solar Calculator
prosolarcalc.toolsSize a solar panel system from your electricity usage: panel count, inverter sizing, roof area and estimated savings. Built to give honest ballpark numbers before you talk to installers.
Voltage Drop Calculator
voltdropcalc.comVoltage drop and wire gauge sizing for electrical circuits, covering copper and aluminium conductors, AC and DC, and common installation scenarios. Helps keep circuits within code limits before any wire is pulled.
Unit Cheat Sheet
unitcheatsheet.comFast conversion reference tables for length, weight, volume, temperature, area and more — the numbers you half-remember, laid out for scanning rather than typing into a converter every time.
Developer tools
JSON Tools
jsontools.toolsFormat, validate, minify and convert JSON entirely in the browser, plus a tokenizer-based repair engine that fixes 23 kinds of broken JSON — trailing commas, single quotes, unquoted keys and worse. Nothing you paste ever leaves the page.
Hash Generator
hashgenerator.toolsGenerate MD5, SHA-1, SHA-2, SHA-3, BLAKE2, RIPEMD-160 and HMAC hashes, plus password KDFs, all client-side. Useful for checksums, integrity verification and development without sending sensitive input to any server.
Base64 Decode
base64decode.toolsEncode and decode Base64 for text and files directly in the browser — JWT payloads, data URIs, email attachments and API responses. Private by architecture: the data stays on your machine.
URL Encode/Decode
urlencodedecode.comPercent-encode and decode URLs, query strings and individual components, with clear handling of the characters that break links — spaces, ampersands, unicode. A small tool that saves real debugging time.
UUID Generator
www.uuidcore.comGenerate UUIDs across versions (v1, v4, v5 and more), in bulk, with validation and format explanations. For developers seeding databases, writing tests or just needing a quick unique identifier.
Epoch Time Converter
epochtime.toolsConvert Unix timestamps to human-readable dates and back, in seconds or milliseconds, across timezones. The tab every developer keeps open when logs, APIs and databases disagree about what time it is.
Crontab Sheet
crontabsheet.comA cron expression reference with the five-field syntax explained, common schedules ready to copy, and the gotchas (day-of-week vs day-of-month) spelled out. For everyone who writes cron twice a year and forgets in between.
Regex Guide
regexguide.comRegular expression reference and pattern library: syntax, character classes, lookarounds, and copy-ready patterns for emails, dates, IPs and more. Written to be readable by humans, not just regex engines.
CIDR Calculator
cidrcalculator.netCIDR notation decoded: network ranges, usable hosts, supernetting and subnet splitting from any block. Built for network engineers and cloud admins carving up address space.
Subnet Mask Calculator
subnetmaskcalc.netFull IPv4 and IPv6 subnetting toolkit with a VLSM planner, cloud-specific modes for AWS, Azure and GCP reserved addresses, and Infrastructure-as-Code export. Goes far beyond a basic mask lookup.
Text & content
Word Counter
wordcounterfree.comCount words, characters, sentences, paragraphs and reading time as you type. Built for essays with word limits, social posts with character limits, and writers tracking output.
Text Repeat
textrepeat.netRepeat any text N times with custom separators — commas, new lines, spaces — for generating test data, lists and bulk input. Trivially simple, surprisingly often needed.
Case Converter
transformcase.comConvert text between UPPERCASE, lowercase, Title Case, Sentence case, camelCase, snake_case, kebab-case and more. Covers both writing cleanup and the variable-naming conversions developers need daily.
Files, media & everyday
PDF Tools
corepdftools.comMerge, split, compress, rotate and convert PDFs directly in the browser. Your documents are processed locally and never uploaded — which matters when the PDF is a contract, a payslip or an ID.
Remove Metadata
removemetadata.toolsStrip EXIF and other hidden metadata — GPS location, device details, timestamps — from photos and files before sharing them. Runs entirely client-side, so the files you're trying to make private stay private.
Pic Toolkit
pictoolkit.comResize, crop, convert and lightly edit images in the browser without installing anything or uploading to a server. Covers the everyday image jobs between 'too small for Photoshop' and 'too private for an online converter'.
Barcode & QR Generator
barcodeandqr.comGenerate retail barcodes (EAN-13, UPC-A, Code 128, ITF-14), QR codes for WiFi, vCards and links — with logos — plus GS1 Digital Links and bulk label sheets. Everything renders in your browser; nothing is uploaded, ever.
ColorCodeKit
colorcodekit.comA developer color toolkit: convert between HEX, RGB, HSL and OKLCH, build palettes and shades, check WCAG contrast, and generate design tokens. Includes named colors, brand colors and platform palettes for reference.
Clock With Us
clockwithus.comWorld clock, time zone comparison and timers in one clean page. For scheduling calls across continents and answering 'what time is it there right now?' without mental arithmetic.
Password Strength
passwordstrength.netTest how strong a password really is, with entropy-based crack-time estimates and concrete improvement advice. Checks run entirely in your browser — the password is never transmitted anywhere.