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Free tools network.

A collection of free, no-signup calculators and developer utilities — all browser-based and privacy-friendly. Grouped by what they do.

Finance & business

indiaemi.comAn EMI calculator built for India, covering home, car and personal loans plus credit-card EMI plans with GST, and the difference between EMI in advance and in arrears. totalinterestcalc.comSee the full lifetime cost of a mortgage or loan — the total interest paid, the amortization schedule and the effect of extra payments, so you understand what borrowing really costs. marginvsmarkup.comConvert between margin and markup and price products correctly, clearing up the common confusion between the two that quietly erodes profit. bestpercentagecalculator.netHandle every kind of everyday percentage problem — percentage of a number, percentage change, increase, decrease and reverse percentages — in one clear tool.

Calculators & construction

thesquarefootagecalculator.comMeasure square footage for floors, walls, rooms and land across many shapes — rectangles, triangles, circles and irregular layouts — with unit conversion handled for you. cubicyardage.comConcrete and bulk-material calculators that work the way contractors do, in cubic yards, for slabs, footings, columns, walls and stairs, with bag counts, ready-mix loads and a waste margin built in. boxvolumecalculator.comCalculate the volume and capacity of boxes, cartons and rectangular containers in any units, useful for packing, shipping and storage planning. tankvolumecalc.comFind the volume and fill level of tanks in many shapes — cylindrical, oval, rectangular and capsule, horizontal or vertical — for water, fuel and chemical storage. dimweightcalc.comCompute dimensional (volumetric) weight for FedEx, UPS, USPS and other carriers and compare it against actual weight, so you can predict shipping charges before you ship. girthcalculator.comMeasure a package's girth and combined length-plus-girth and check it against carrier oversize limits before you pay for shipping. actonnagecalc.comWork out the air-conditioner tonnage and cooling load a room or whole home needs, based on area, climate, insulation and sun exposure, so you neither undersize the unit nor waste money oversizing it. unitcheatsheet.comA fast reference and converter for units of length, weight, volume, temperature and more, with the common conversions you actually look up.

Solar, electrical & energy

solarbatterybankcalc.comSize a complete off-grid or backup solar system end to end — battery bank, array, charge controller and inverter — from your real daily load, with the chemistry constants generic tools get wrong. prosolarcalc.toolsA set of professional solar sizing and design tools for installers and serious DIY builders, covering the calculations that go into planning a photovoltaic system from panels through to storage. voltdropcalc.comCalculate voltage drop and the correct wire gauge for any DC or AC run across NEC, CEC, BS 7671, AS/NZS and IEC standards, so you don't lose power or overheat conductors.

Health

calorieskit.comA suite of calorie, macronutrient and body-composition calculators — daily calorie needs, protein targets, lean body mass and more — with clear methodology behind every number. bmibmrcalc.comCalculate body mass index and basal metabolic rate, with the daily-calorie estimates that follow from them, to set a realistic starting point for diet and fitness goals.

Developer & web utilities

jsontools.toolsFormat, validate, minify and explore JSON in your browser, with a tree viewer that makes large or messy payloads easy to read and debug. base64decode.toolsEncode text and files to Base64 or decode them back, entirely client-side so nothing you paste ever leaves your machine. urlencodedecode.comPercent-encode and decode URLs and query strings so special characters are transmitted safely, with full Unicode support. hashgenerator.toolsGenerate MD5, SHA-1, SHA-256 and other cryptographic hashes from text or files for checksums, integrity checks and fingerprinting. uuidcore.comGenerate UUIDs in bulk and learn how the different versions work, with copy-ready output for development and testing. regexguide.comBuild, test and understand regular expressions with live matching and a reference that explains each token in plain language. crontabsheet.comBuild cron schedules visually and read back exactly when a crontab expression will run, with a cheat sheet of common patterns. passwordstrength.netTest how strong a password is and how long it would take to crack, with practical guidance on building passwords that resist attacks, checked locally and never sent anywhere.

Networking

cidrcalculator.netWork out network and broadcast addresses, host ranges and subnet sizes from CIDR notation, with clear breakdowns for network planning. subnetmaskcalc.netCalculate subnet masks, host counts and address ranges, with worked examples and code snippets in several languages for network engineers.

Color, image & files

colorcodekit.comConvert color codes between HEX, RGB, HSL and more, build palettes and gradients, and export tokens for SwiftUI, Flutter and Jetpack Compose. pictoolkit.comA toolkit of browser-based image utilities for resizing, converting and editing pictures without uploading them anywhere. corepdftools.comMerge, split, compress, rotate and password-protect PDF files client-side, keeping your documents private because they never leave your device. removemetadata.toolsStrip hidden metadata — EXIF, location, author and more — from images, PDFs, Office files, audio and video entirely in your browser, so nothing is ever uploaded. barcodeandqr.comGenerate barcodes and QR codes in many formats and export them print-ready as PNG or PDF, all rendered locally in your browser.

Text & time

wordcounterfree.comCount words, characters, sentences and paragraphs and estimate reading time as you type, useful for essays, articles and content limits. transformcase.comConvert text between upper case, lower case, title case, sentence case and more in one click, handy for cleaning up copy and code. textrepeat.netRepeat, duplicate and generate blocks of text quickly, with control over separators and counts for testing and formatting. theagecalculator.netCalculate exact age in years, months and days, plus milestones, birthday countdowns and age comparisons between people. calculatehours.netAdd up the hours between start and end times, including overnight spans and breaks, useful for timesheets, shifts and payroll. clockwithus.comCheck the current time across world cities and time zones at a glance, for scheduling calls and coordinating across regions. epochtime.toolsConvert between Unix epoch timestamps and human-readable dates in any time zone, in seconds or milliseconds, in both directions.
These are sites in our own network, linked openly with rel="nofollow noopener". We link them because they're built to the same standard — free, browser-based and no signup — not as paid placements.