Free online tools that run in your browser
109 calculators, converters, generators and file tools. Your files are opened, read and processed on your own device. They are never uploaded, so we cannot read them, store them, or lose them.
No sign-up
No watermarks
Works offline
Categories
Finance
15Mortgage, loan, interest and percentage maths with full schedules.
Health
7Body mass index and daily energy needs, using published formulas.
Math & Dates
9Scientific notation, ages, date spans, grades and GPA.
Text
8Counting, case conversion and readability, without uploads.
Generators
3Passwords, QR codes and random numbers from local entropy.
Developer
19JSON, Base64, hashes, UUIDs and URL encoding.
Image
15Compress, resize and change format without uploading photos.
PDF
6Merge, split, shrink and export documents locally.
Converters
27Video and audio formats, and units with exact conversion factors.
Find your tool
All 109 tools →Tick a category or type a keyword. The list narrows as you type.
Showing 12 of 109
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Age calculator
Math & DatesFind an exact age in years, months and days from any date of birth, plus the total in weeks, days and hours and the countdown to the next birthday.
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BMI calculator
HealthCalculate body mass index from height and weight in metric or imperial units, see which WHO category it falls in, and get the healthy weight range for your height.
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cm to inches
ConvertersConvert centimetres to inches and back using the exact international factor, with a reference chart and the formula shown.
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Image compressor
ImageCompress images by quality or to a target file size, in batches, with the original never leaving your device.
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Image to text
ImagePull the text out of a photo, screenshot, scan or PDF, as plain text or with the headings, lists and tables kept intact.
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JSON formatter
DeveloperFormat, validate and minify JSON with precise error locations, optional key sorting and a structural summary of what the document contains.
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Mortgage calculator
FinanceWork out the full monthly cost of a home loan, covering principal, interest, tax, insurance and PMI, with a year-by-year amortisation schedule.
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Password generator
GeneratorsGenerate strong random passwords using your browser's cryptographic randomness, with entropy shown in bits and no password ever transmitted.
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PDF merge
PDFCombine any number of PDFs into one document in the order you choose, without uploading a single page.
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Video converter
ConvertersConvert MOV, MKV, AVI, WebM and MP4 in any direction, with the whole conversion running inside your browser.
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Word counter
TextCount words, characters, sentences and paragraphs as you type, with reading time, speaking time and the most-used words in your text.
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kg to lbs
ConvertersConvert kilograms to pounds and back with the exact international factor, plus a reference chart and stone conversions.
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Loan calculator
FinanceFind the monthly payment, total interest and full repayment schedule for any fixed-rate loan, whether car, personal, student or business.
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MOV to MP4
ConvertersTurn iPhone and QuickTime MOV files into MP4, usually without re-encoding a single frame.
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PDF split
PDFExtract specific pages, split into one file per page, or break a document into fixed-size chunks, without uploading it.
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Celsius to Fahrenheit
ConvertersConvert °C to °F and back with the formula shown, plus a reference chart of everyday and body temperatures.
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Compound interest calculator
FinanceSee how savings and investments grow over time, with regular contributions and any compounding frequency, plus a year-by-year balance table.
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Image converter
ImageConvert images between JPG, PNG, WebP and AVIF in batches, with quality control and transparency handled correctly.
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PDF compress
PDFShrink a PDF either losslessly, keeping text sharp and selectable, or aggressively by redrawing pages as images, with the trade-off stated plainly.
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QR code generator
GeneratorsCreate QR codes for links, Wi-Fi networks, email, phone and SMS. Download as PNG or SVG, with no watermark, no account and no expiry.
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Scientific calculator
Math & DatesA full scientific calculator with trigonometry, logarithms, powers, roots and factorials. Type expressions directly or use the keypad.
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HEIC to JPG
ImageConvert iPhone HEIC photos to JPG in batches, on Windows and Android as well as on a Mac.
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Percentage calculator
FinanceWork out a percentage of a number, express one number as a percentage of another, or find the percentage increase or decrease between two values.
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QR code scanner
ImageRead a QR code with your camera or from a screenshot, and see what it actually contains before you act on it.
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Amortization calculator
FinanceGenerate a full amortisation schedule payment by payment, find the crossover month, and see what an extra payment each month actually saves.
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Grade calculator
Math & DatesWork out your current weighted grade from assignments completed so far, and find the score you need on what remains to hit a target.
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PDF to JPG
PDFTurn PDF pages into JPG or PNG images at any resolution, choosing which pages to convert, with everything rendered in your browser.
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Text diff
TextCompare two blocks of text and see exactly what changed, by line or by word, with insertions and deletions marked.
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Refinance calculator
FinanceSee what refinancing really saves: the new payment, how many months it takes to earn back closing costs, and what restarting the term costs you.
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Time calculator
Math & DatesAdd or subtract durations, or total a whole list of them, in any format people actually type: 1:30, 90m or 1h 30m.
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Word to PDF
PDFTurn a .docx into a PDF inside your browser, keeping headings, lists, tables and pictures, without the document ever leaving your device.
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Audio converter
ConvertersConvert between MP3, M4A, WAV, AAC, OGG and FLAC in batches, with the bitrate under your control.
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MB to GB
ConvertersConvert megabytes to gigabytes in both the decimal (1000) and binary (1024) conventions, and see why your drive looks smaller than the box said.
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MP3 converter
ConvertersTurn any audio or video file into MP3, at a bitrate you choose, without uploading it anywhere.
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mph to km/h
ConvertersConvert mph to km/h with the exact factor, plus a speed-limit chart for driving abroad and the mental arithmetic that gets you close.
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Regex tester
DeveloperTest a regular expression against sample text with live highlighting, capture groups broken out, and replacement preview.
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MP4 to MP3
ConvertersPull the soundtrack out of an MP4 and save it as MP3, without the video ever leaving your device.
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Video to MP3
ConvertersExtract the soundtrack from MP4, MOV, MKV, AVI or WebM and save it as MP3, all inside your browser.
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Base64 encode/decode
DeveloperEncode and decode Base64 with full Unicode support, including a URL-safe alphabet, and encode any file to Base64 without uploading it.
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Batch image to text
ImageRead text from a whole folder of images or a long PDF in one pass, then take it as one file or one text file per page.
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Calorie calculator
HealthEstimate the calories you burn each day using the Mifflin-St Jeor equation, with targets for maintaining, losing or gaining weight.
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Character counter
TextCount characters with and without spaces as you type, and see live progress against SMS, X, meta description and title tag limits.
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Date calculator
Math & DatesCount the days, weeks and working days between two dates, or add and subtract days, weeks, months and years from any date.
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Image resizer
ImageResize an image to exact pixel dimensions or a percentage, with aspect ratio locking and presets for common social and web sizes.
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Random number generator
GeneratorsGenerate random numbers in any range using cryptographic randomness, with options for no repeats and sorted output, for draws, sampling and testing.
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BMR calculator
HealthCalculate basal metabolic rate using Mifflin-St Jeor, Harris-Benedict or Katch-McArdle, and see total daily burn at every activity level.
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Case converter
TextConvert text between upper, lower, title, sentence, camel, Pascal, snake, kebab and constant case, plus alternating and inverse case.
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Image translator
ImageRead the text out of a photo on your device, then translate it, with the headings, lists and tables kept in place.
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MKV to MP4
ConvertersConvert Matroska MKV files to MP4 in seconds, copying the video across rather than re-encoding it.
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UUID generator
DeveloperGenerate RFC-compliant UUIDs in bulk, either random v4 or time-sortable v7, with formatting options and no server involvement.
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AVI to MP4
ConvertersBring old AVI footage from camcorders and 2000s-era files into MP4 that modern devices will actually play.
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Bulk PDF compress
PDFQueue a folder of PDFs, compress every one of them with the same settings, and take the whole batch away as a ZIP.
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Feet to metres
ConvertersConvert feet to metres and back with the exact international factor, plus a chart covering heights, room sizes and altitudes.
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GPA calculator
Math & DatesCalculate a grade point average from any number of courses on the unweighted 4.0 or weighted 5.0 scale, with credit hours taken into account.
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Hash generator
DeveloperGenerate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes from text or any file, computed entirely on your device.
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Ideal weight calculator
HealthSee what the four classic ideal-weight formulas say for your height, how far apart they are, and the BMI range that is more useful than any of them.
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Slug generator
TextTurn titles into clean URL slugs, converting accents properly, stripping filler words and handling a whole list at once.
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Barcode scanner
ImageRead EAN, UPC, Code 128, ITF, Data Matrix and PDF417 with your camera or from a photo, with the check digit verified.
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Body fat calculator
HealthEstimate body fat percentage from a tape measure using the US Navy method, with fat and lean mass broken out and a BMI-based cross-check.
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Miles to km
ConvertersConvert miles to kilometres and back with the exact factor, plus speed limits, running distances and a reference chart.
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URL encoder/decoder
DeveloperPercent-encode and decode URLs and query parameters, with a breakdown of any URL into its origin, path and decoded parameters.
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WebM to MP4
ConvertersConvert WebM recordings and downloads to MP4 so phones, editors and social platforms will accept them.
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Epoch converter
DeveloperConvert Unix timestamps to human dates and back, in seconds or milliseconds, with a live clock and a relative-time readout.
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Lorem ipsum
TextGenerate placeholder text by paragraph, sentence, word or list item, in classic Latin or in Indonesian for layouts that will hold Indonesian copy.
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Macro calculator
HealthTurn a daily calorie target into grams of protein, carbohydrate and fat, with presets for balanced, low-carb, endurance and ketogenic splits.
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Due date calculator
HealthEstimate a due date from a last period, a conception date or a known due date, with current gestational age, trimesters and key milestones.
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Hours calculator
Math & DatesTotal a week of shifts from start and end times, subtract breaks, handle overnight shifts, and optionally calculate gross pay with overtime.
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JWT decoder
DeveloperDecode a JSON Web Token to read its header and claims, with expiry checked and timestamps rendered as dates, all in your browser.
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Remove line breaks
TextStrip unwanted line breaks from pasted text while keeping paragraph breaks, and tidy up the extra spaces and smart quotes that come with them.
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Retirement calculator
FinanceProject a retirement pot in today's money, see how much of it is growth rather than contributions, and estimate a sustainable income from it.
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Colour converter
DeveloperConvert between HEX, RGB and HSL, and check WCAG contrast against white and black in the same step.
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Countdown timer
Math & DatesCount down live to any date and time, with days, hours, minutes and seconds, plus working days and the weekday it falls on.
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Reverse text
TextReverse text by character, by word order or by line order, with the character reversal handling emoji and accents correctly.
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Salary calculator
FinanceConvert pay between hourly, daily, weekly, monthly and annual, accounting for hours worked and unpaid leave.
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Time zone converter
Math & DatesConvert a time across as many cities as you need at once, with daylight saving resolved for the actual date you entered.
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UTM builder
DeveloperBuild correctly tagged campaign URLs, with existing UTM parameters replaced rather than duplicated and casing normalised.
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JPG to PNG
ImageConvert JPG and JPEG photos to lossless PNG in batches, entirely inside your browser.
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Meta tag generator
DeveloperGenerate title, description, Open Graph and Twitter card tags with live length warnings and a search-result preview.
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Tip calculator
FinanceWork out the tip and the total, split it between any number of people, and round the tip or the total up to a clean number.
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CSS minifier
DeveloperMinify or beautify CSS with a parser that never corrupts strings, url() values or calc() expressions.
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Discount calculator
FinanceWork out a sale price, stack two discounts correctly, or find what percentage off you actually got.
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PNG to JPG
ImageConvert PNG images to JPG with adjustable quality and transparency flattened to white, all inside your browser.
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M4A to MP3
ConvertersConvert iPhone voice memos, iTunes tracks and other M4A files to MP3 that anything will play.
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Sales tax calculator
FinanceAdd sales tax to a price or strip it back out of a total, with the arithmetic that catches almost everyone shown explicitly.
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WebP to PNG
ImageConvert WebP images to PNG with transparency preserved, for software that will not open WebP files.
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HTML encode/decode
DeveloperEscape the five characters that break HTML, or decode any named or numeric entity back to plain text.
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Image to Base64
ImageConvert an image to a Base64 data URI, ready to paste into CSS or HTML, with guidance on whether inlining is worth it.
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sq ft to sq m
ConvertersConvert square feet to square metres with the exact factor, plus why area conversion squares the length factor and a chart of common property sizes.
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VAT calculator
FinanceAdd VAT to a net price or extract it from a gross total, with rates for the UK, EU and other common jurisdictions.
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WAV to MP3
ConvertersCompress large WAV recordings into MP3 at a bitrate you choose, without uploading anything.
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Base converter
DeveloperConvert between binary, octal, decimal and hexadecimal using arbitrary-precision arithmetic, so 64-bit values stay exact.
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Favicon generator
ImageGenerate the favicon and app icon sizes that still matter in 2026, with a maskable variant and the HTML to install them.
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Gallons to litres
ConvertersConvert US and imperial gallons to litres with exact factors, and see why the two gallons differ by twenty per cent.
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MP3 to WAV
ConvertersDecode MP3 files to uncompressed 16-bit WAV for editing, transcription and software that refuses compressed audio.
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ROI calculator
FinanceCalculate return on investment as a percentage and as an annualised rate, so holdings of different lengths can actually be compared.
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Average Down Calculator
FinanceAdd every purchase of a stock and see your true average price, the break even price once fees are counted, and how much more you would have to buy to reach the average you want.
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Cron generator
DeveloperBuild or decode a cron expression, read it back in plain English, and see the next eight times it will actually fire.
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Inches to cm
ConvertersConvert inches to centimetres with the exact factor of 2.54, plus screen sizes, paper sizes and a full reference chart.
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lbs to kg
ConvertersConvert pounds to kilograms with the exact factor, plus body weight, luggage allowance and gym plate references.
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Position Size Calculator
FinanceSize a trade from the loss you can afford rather than the cash you happen to have. Enter your capital, your risk per trade and your stop, and get the quantity, the money at risk and the reward to risk ratio.
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Robots.txt generator
DeveloperBuild a robots.txt with multiple user-agent groups, sitemap declarations and an optional block for AI training crawlers.
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Fahrenheit to Celsius
ConvertersConvert °F to °C with the formula shown, plus oven temperatures, body temperature and a weather reference chart.
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Keyword density
DeveloperAnalyse which words and phrases dominate a piece of copy, check a specific target keyword, and see whether anything reads as overused.
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KB to MB
ConvertersConvert kilobytes to megabytes in both the decimal and binary conventions, with a reference chart of common file sizes.
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SERP preview
DeveloperSee how a title and description will render in search results, measured by pixel width rather than character count.
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Cups to ml
ConvertersConvert cups to millilitres, with the three different cups explained and a note on why baking should be weighed instead.
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Schema generator
DeveloperGenerate valid JSON-LD for Organization, LocalBusiness, Article, Product, FAQPage and BreadcrumbList, ready to paste into your head.
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Knots to km/h
ConvertersConvert knots to km/h and mph with the exact factor, plus a Beaufort wind scale reference and why aviation still uses them.
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TinyPNG alternative
ImageThe same class of compression the popular upload based services use, running inside your browser instead of on their servers.
No tool matches that yet. Browse all tools
Show all 109 tools
How processing in the browser works
When you drop a PDF into a typical online tool, the file is uploaded to a server, processed there, and sent back. That server has your document. How long it keeps it, who can read it and what happens in a breach are all questions you answer by reading a privacy policy and trusting it.
These tools work differently. The code that merges your PDF or compresses your photo is JavaScript and WebAssembly that runs inside your browser tab, using your own processor and memory. The file is read from disk by the browser, handled in memory, and written back out as a download. At no point is there a request carrying it anywhere.
That is not a claim you have to take on trust. Open your browser’s developer tools, switch to the Network tab, and use any tool on this site. You will see the page and its code load, and then nothing: no upload, whatever the size of your file.
What this changes in practice
- No size limits from us. There is no upload to cap. The only constraint is your device’s memory.
- No queue. Nothing waits on a shared server, so a busy afternoon does not slow you down.
- It works offline. Once a page has loaded, it keeps working with no connection at all.
- Confidential files stay confidential. Contracts, medical records and client work can be processed without a copy existing anywhere else.
What we do collect
Privacy-friendly, cookieless analytics that count page views and nothing else: no identifiers, no profiles, no cross-site tracking. If you accept the optional cookies, we additionally use Google Analytics to understand which tools are worth building next. You can change that choice at any time from the footer, and either way it never touches the files you process. Full detail is in the privacy policy.
