All Tools
Every tool on ToolStack, organized by category.
Developer Tools
JSON FormatterFormat, beautify, minify and validate JSON instantly — right in your browser.JSON ValidatorValidate JSON instantly and find syntax errors with the exact line, column and position — right in your browser.Base64 Encoder/DecoderEncode text to Base64 and decode Base64 back to text with full Unicode and emoji support — 100% in your browser.URL Encoder / DecoderEncode text for URLs with encodeURIComponent or encodeURI, and decode percent-encoded strings.Unix Timestamp ConverterConvert Unix timestamps to readable dates and back, with seconds and milliseconds support.Hash GeneratorCompute MD5, SHA-1, SHA-256 and SHA-512 hashes of any text, entirely in your browser.JWT DecoderDecode JSON Web Tokens to inspect the header, payload and expiration — without sending the token anywhere.Diff CheckerCompare two blocks of text line by line and see exactly what was added, removed or left unchanged.Regex TesterTest a regular expression against your own text, highlight every match and inspect capture groups.JSON to CSV ConverterTurn a JSON array of objects into clean CSV, ready for Excel, Google Sheets or a database import.Number Base ConverterConvert between binary, octal, decimal and hexadecimal with exact BigInt precision.HTML Entity EncoderEscape or decode HTML entities, with a minimal mode for code and a full mode for every special character.CSS Box Shadow GeneratorDesign a CSS box-shadow with live sliders, presets and a preview, then copy the ready-to-paste rule.Border Radius GeneratorShape four corners independently, link them together and copy the CSS border-radius rule.JSON to TypeScriptTurn any JSON payload into clean TypeScript interfaces or type aliases, generated in your browser.Cron Expression ParserExplain a cron expression in plain language and preview the next run times, right in your browser.Markdown to HTMLConvert Markdown into clean HTML, preview it in a sandbox and copy or download the result.HTML to MarkdownConvert HTML into tidy Markdown — headings, lists, tables, links and code blocks included.QR Code ScannerDecode a QR code from an image and read the link, Wi-Fi details or contact card it contains.JSON to Go StructGenerate Go structs with JSON tags from a JSON sample.JSON to Python ModelGenerate Python dataclasses or Pydantic models from a JSON sample.CIDR CalculatorExpand a CIDR block into its network, mask, wildcard and host range.JSON to YAMLConvert JSON into clean, readable YAML with configurable indent and key sorting.YAML to JSONConvert YAML into JSON, including multi-document files and key sorting.cURL to CodeTurn a curl command into JavaScript, Python, Go or PHP code.LLM Token CounterCount tokens for GPT, Claude and Gemini models, check the context window left, and see how one Chinese character can cost 0.6 or 1.2 tokens depending on the model.Browser Info & Screen Resolution DetectorRead your screen resolution, viewport size, device pixel ratio, GPU, CPU cores, time zone and connection quality from one table — including the physical pixel count behind the scaling.What Is My IP?Show the public IP address your device presents to the internet, plus country, the Cloudflare data centre serving you, TLS version, protocol and VPN indicators.
Text Tools
Word CounterCount words, characters, sentences, paragraphs and lines in real time, with estimated reading time. Works with English, Chinese, Japanese, Korean and any Unicode text — everything stays in your browser.Case ConverterConvert text between camelCase, snake_case, kebab-case, PascalCase and other naming styles instantly.Remove Duplicate LinesDelete duplicate and blank lines, trim whitespace and sort a list — all locally in your browser.Find and ReplaceReplace every match in your text, with regex, whole-word and case-sensitive options.Text Diff CheckerCompare two blocks of text line by line and see exactly what was added, removed or left unchanged.Sort Text LinesSort, reverse or shuffle lines of text — alphabetically, by length or numerically, with dedupe options.
Converters
Unit ConverterConvert between units of length, weight, temperature, volume, area and speed.CM to InchesConvert centimetres to inches instantly — fast, free and private.Inches to CMConvert inches to centimetres instantly — fast, free and private.Miles to KMConvert miles to kilometres instantly — fast, free and private.KG to LBConvert kilograms to pounds instantly — fast, free and private.Feet to CMConvert feet to centimetres instantly, with a lookup table and the exact formula.Meters to FeetConvert metres to feet instantly, with a lookup table and the exact 0.3048 factor.KM to MilesConvert kilometres to miles instantly, with race distances in the lookup table.LBS to KGConvert pounds to kilograms instantly, with a body-weight lookup table.Celsius to FahrenheitConvert Celsius to Fahrenheit instantly, including negative values and body heat.Fahrenheit to CelsiusConvert Fahrenheit to Celsius instantly, with a table for weather and oven temperatures.Ounces to GramsConvert ounces to grams instantly, with a table for cooking and portion sizes.KPH to MPHConvert kilometres per hour to miles per hour instantly, with a speed lookup table.Grams to OuncesConvert grams to ounces instantly, with a table for the values people look up most.Miles per Hour to Kilometers per HourConvert miles per hour to kilometers per hour instantly, with a table for the values people look up most.Centimeters to FeetConvert centimeters to feet instantly, with a table for the values people look up most.Feet to MetersConvert feet to meters instantly, with a table for the values people look up most.Gigabytes to MegabytesConvert gigabytes to megabytes instantly, with a table for the values people look up most.Megabytes to KilobytesConvert megabytes to kilobytes instantly, with a table for the values people look up most.Hours to MinutesConvert hours to minutes instantly, with a table for the values people look up most.Minutes to HoursConvert minutes to hours instantly, with a table for the values people look up most.Acres to Square FeetConvert acres to square feet instantly, with a table for the values people look up most.US Cups to MillilitersConvert US cups to milliliters instantly, with a table for the values people look up most.Pixels to REMConvert pixels to rem instantly, with a table for the values people look up most.Kilopascals to PSIConvert kilopascals to PSI instantly, with a table for the values people look up most.
Calculators
Age CalculatorCalculate exact age in years, months, days and more — right in your browser.Percentage CalculatorCalculate percentages in multiple modes: X% of Y, X is what % of Y, and percent change.BMI CalculatorCalculate your Body Mass Index instantly with metric and imperial units.Tip CalculatorCalculate tip amounts and split bills easily with preset or custom tip percentages.Discount CalculatorCalculate the final price after a discount and see how much you save.Mortgage CalculatorEstimate the monthly payment, total interest and total repayment for a fixed-rate mortgage.Compound Interest CalculatorSee how savings or investments grow with compound interest and optional monthly contributions.Calorie CalculatorEstimate your basal metabolic rate, daily calorie needs and a target intake for losing, keeping or gaining weight.Sales Tax CalculatorAdd sales tax or VAT to a price, or extract the tax from a tax-inclusive total.Aspect Ratio CalculatorResize an image or video while keeping its aspect ratio exactly intact.Sleep CalculatorFind the best bedtime or wake-up time based on 90-minute sleep cycles.Business Days CalculatorCount working days between two dates, or add business days to a date.
Image Tools
Image CompressorCompress JPG, PNG and WebP images right in your browser. Adjust quality, format and size, download the results — images never leave your device.Image ResizerResize images to exact dimensions while keeping aspect ratio — right in your browser.JPG to PNGConvert JPG images to PNG format instantly — 100% in your browser.PNG to JPGConvert PNG images to JPG format instantly — 100% in your browser.JPG to WebPConvert JPG images to WebP format for smaller file sizes — right in your browser.WebP to JPGConvert WebP images to JPG format for maximum compatibility — right in your browser.Image CropperCrop images to exact dimensions with preset aspect ratios — right in your browser.HEIC to JPGConvert HEIC (iPhone) photos to JPG format — right in your browser.Image to Base64 ConverterConvert PNG, JPG, GIF, WebP or SVG images into Base64 data URIs, ready to paste into HTML or CSS.SVG to PNG ConverterRender SVG files or pasted SVG markup to crisp PNG images at any width, with an optional white background.Favicon GeneratorTurn one image into a complete PNG favicon set — 16, 32, 48, 180, 192 and 512 px — plus the HTML to paste.Image to ICOTurn a PNG, JPG or WebP image into a multi-size Windows .ico file, right in your browser.Image WatermarkStamp text on a photo, choose the corner, opacity and size, then download the watermarked image.Image Rotate & FlipRotate an image by 90, 180 or 270 degrees, flip it horizontally or vertically, then download it.
File Tools
Merge PDF FilesCombine several PDFs into one document — reorder, remove and download, without uploading.Split PDFSplit a PDF into single pages, fixed-size chunks or custom ranges and download the parts.Images to PDFTurn JPG or PNG images into a single PDF, one page per image, with A4, Letter or fit-to-image pages.Excel to CSVConvert an Excel workbook into CSV — pick the sheet, choose the delimiter and preview before downloading.CSV to ExcelTurn a CSV file into a real Excel workbook (.xlsx) without uploading anything.JSON to ExcelConvert JSON arrays, objects or key-value pairs into an Excel workbook.PDF Page EditorReorder, rotate, remove and restore PDF pages, then download the result.PDF WatermarkStamp text watermarks on every page of a PDF, with tiling, colour and rotation.PDF Page NumbersAdd page numbers to a PDF with your choice of position, format and starting number.PDF to JPGRender PDF pages as JPG images and download them one by one.
Color Tools
Color PickerPick any color and copy its HEX, RGB, HSL and HSV values instantly.HEX to RGBConvert HEX color codes to RGB values instantly — free and private.RGB to HEXConvert RGB values to a HEX color code instantly — free and private.Color ConverterConvert between HEX, RGB, HSL, HSV and HWB color formats in any direction.Gradient GeneratorCreate CSS linear and radial gradients visually and copy the CSS code.Contrast CheckerCheck the WCAG contrast ratio between text and background colors instantly.CSS Color GeneratorTurn a base color into a 10-step shade scale and export it as CSS variables.Color Blindness SimulatorPreview a colour or image through protanopia, deuteranopia, tritanopia and achromatopsia.Image Color PickerPick exact colours from any image and get hex, RGB and HSL values.
SEO Tools
UTM Link BuilderBuild campaign URLs with UTM parameters for Google Analytics, Matomo and every other analytics tool.Meta Tag GeneratorGenerate HTML meta tags for title, description, robots, canonical, Open Graph and Twitter cards.Keyword Density CheckerAnalyze word frequency and keyword density in any text, with optional English stop-word filtering.Slug GeneratorTurn titles or URLs into clean SEO slugs, with separator, case and Unicode options.Open Graph PreviewPreview how a link looks on social platforms and audit its OG tags.JSON-LD GeneratorBuild schema.org JSON-LD for articles, products, FAQs and organisations.
Time Tools
Countdown TimerSet a countdown to any date and time — see days, hours, minutes and seconds remaining.Date Difference CalculatorCount the days, weeks, months and business days between two dates.Add Days to DateAdd or subtract days, weeks, months or years from any date and see the resulting weekday.Time Zone ConverterConvert a date and time between any two IANA time zones, with daylight saving handled automatically.World ClockCompare the current time in cities around the world, with day offsets and a searchable zone list.Timezone Meeting PlannerCompare one meeting time across up to fifteen cities and spot working hours.
Generators
QR Code GeneratorGenerate QR codes for any text or URL instantly — customisable size and error correction.Password GeneratorGenerate strong, random passwords with customisable length and character types.UUID GeneratorGenerate random RFC 4122 version 4 UUIDs in bulk, with optional uppercase and no-hyphen formats.Lorem Ipsum GeneratorGenerate lorem ipsum placeholder paragraphs, sentences or words for mockups and layouts.Random Number GeneratorGenerate cryptographically random integers in any range, with optional unique values.Barcode GeneratorCreate CODE128, EAN, UPC and other barcodes from a value, then download them as PNG or SVG.WiFi QR Code GeneratorCreate a scannable QR code that joins a WiFi network without typing the password.vCard QR Code GeneratorBuild a QR code that adds your contact details to a phone in one scan.Fake Data GeneratorGenerate realistic test records and export them as CSV or JSON.