Everyday and developer utilities

Ac Electricity | How to use and interpret results Estimate cooling energy from the appliance's electrical draw and operating schedule. The cost is a… Add Days to Date Calculator — Free Move a calendar date forward or backward without counting cells in a calendar. The result includes its… Age Calculator | How to use and interpret results Find completed years of age on a chosen calendar date, with the next birthday nearby. An optional… Age Calculator — From Birthdate, Free Break the elapsed time between a birthdate and a selected date into years, months, and days. A future event… Aim Test | How to use and interpret results This ten-target activity records how far a click lands from each target's centre. It is a small pointing… Ascii Art Create a text banner or turn an image into a pattern of characters chosen to represent brightness. The… Aspect Ratio Calculator — Ratio and Target Height | How to use and interpret results Reduce a pair of image dimensions to a simple ratio and find a proportional height at a new width. This… Baekil Dol Compare the date 100 days after birth with the first anniversary. The implementation adds 100 days to the… Barcode Generator | How to use and interpret results Create a linear barcode for a stock label or a scanning experiment. Encoding follows the selected library… Base64 Encode & Decode — In Browser Encode readable text as Base64 or decode it back into text for sample payloads and debugging. This changes… Base64 Text | How to use and interpret results Encode UTF-8 text as Base64 or decode that representation back into text. It is useful for checking a… Base64 to Image Preview an image supplied as encoded text and save a local copy. It is useful when an application returns… Binary Converter | How to use and interpret results View a string as binary UTF-8 bytes rather than as one large binary integer. A Korean syllable occupies… Biorhythm This entertainment tool plots periodic sine curves from the number of days since a birthdate. The values are… Metric BMI with Explicit Category Boundaries This metric calculator reports BMI to one decimal place. Its category labels change at 23 and 25, so a… Adult BMI in Metric or US Units This calculator reports adult BMI to two decimal places and shows categories using boundaries including… Resting Energy Estimate with Mifflin–St Jeor The screen calls the result BMR, but the Mifflin calculation is an estimate of resting energy rather than a… Compare Circumference and BMI Fat Estimates Choose between a Navy circumference equation and a BMI-and-age regression. These methods use different… Body-Fat Estimate from Tape Measurements This calculator estimates body fat from height and circumferences without requiring body weight. Differences… Box Shadow Generator | How to use and interpret results Adjust a card or button shadow while inspecting its CSS declaration. Separate offset, blur, spread and… Browser Notepad Keep short titled notes in this browser and reopen them from the saved list. Editing a selected note updates… Eight-Question Work Burnout Reflection These eight original questions help you reflect on work-related exhaustion. WHO describes burnout as an… Byte Converter — B, KiB, MiB, GiB, TiB | How to use and interpret results Convert storage sizes with a fixed factor of 1024 between adjacent units. Distinguish the selector's… Daily Caffeine from Drinks Track daily caffeine by multiplying drink counts by caffeine per serving. The FDA’s 400 mg reference for… Resting Energy and Activity Multiplier This screen combines a resting-energy equation with an activity multiplier. Similar exercise frequency does… Calorie Gap and One-Week Arithmetic Compare two daily energy figures. Converting the weekly gap with 7,700 kcal per kg is a fixed arithmetic… Case Converter Change letter case or reshape word boundaries into identifier styles such as snake, camel, and kebab case.… Celsius to Fahrenheit Converter — Free | How to use and interpret results Convert Celsius to Fahrenheit while retaining a Celsius reference in the result. You can also select… Character Counter Compare text length with and without whitespace, line count, and UTF-8 byte size. These figures help… Character Counter — Words, Bytes, Free | How to use and interpret results Count text characters, whitespace-separated words, lines and UTF-8 bytes in one view. Keeping character and… Checksum Generator — SHA-256, SHA-1, Local Calculate a hexadecimal SHA-256 or SHA-1 digest of a message to compare exact text across environments. A… Chmod Calculator | How to use and interpret results Compare owner, group and other-user read/write/execute bits in octal and symbolic form. This is a… CIDR Calculator Derive an IPv4 network range and subnet mask from an address and CIDR prefix length. Use it to understand an… Circle Area Calculator — πr² | How to use and interpret results Calculate the area and circumference of a circle from its radius. The two outputs help separate surface… Clean Plain Text — Strip Clutter, Free Clean a small copied HTML fragment into readable plain text. Tags become separators and selected character… cm to Inches Converter — Height, DIY | How to use and interpret results Compare centimetre measurements with inch-based dimensions for furniture or a display. The selectable units… College GPA Calculator — 4.0 Scale Compute a credit-weighted average from course grades. The tool multiplies grade points by credits and… Color Converter | How to use and interpret results Synchronize a HEX colour with its three RGB channels and an on-screen swatch. This helps transfer a basic… Color Palette Build candidate color combinations from a starting color using relationships such as analogous and… Color Picker | How to use and interpret results Read a browser-selected colour as HEX, RGB and HSL at the same time. Hue, saturation and lightness provide a… On-Screen Colour Number Activity The browser creates coloured dot patterns for a number-reading activity. These are not validated Ishihara… Contrast Ratio Checker — WCAG, Free Calculate contrast from the relative luminance of two sRGB colors and compare common text thresholds. Use it… JSON to CSV Converter — Free, Local | How to use and interpret results Turn JSON records into CSV text and a file named rows.csv. This is a tabular export step, not a nested-data… Cooking Unit Converter — Cups, ml, Free Convert US customary cooking volumes such as cups and tablespoons into milliliters or liters. The result… Countdown Timer | How to use and interpret results Display the days, hours, minutes and seconds remaining until a chosen date and time. The countdown subtracts… Countup Timer Display elapsed hours, minutes, and seconds from a selected starting moment. Unlike a stopwatch started by a… Cron Explainer | How to use and interpret results Read a five-field cron expression as minute, hour, day, month and weekday parts. The explanation expands… Cron Generator Assemble the five conventional cron fields for minute, hour, day, month, and weekday. The tool drafts an… Crontab Builder — Cron Schedule, Free | How to use and interpret results Assemble a five-field cron time expression from separate minute, hour, day, month and weekday inputs. The… CSS Box Shadow Generator — Copy Free Build one box-shadow declaration from offsets, blur, spread, color, and an optional inset flag. The result… CSS Gradient Helper — Copy CSS, Free | How to use and interpret results Generate a CSS background declaration for a two-colour linear or radial gradient. It is a quick way to test… CSV to JSON Convert a small comma-separated table into a JSON array, optionally using the first row as object keys. It… Curl Converter | How to use and interpret results Turn the URL, method, headers and body of a copied cURL command into a fetch draft. The converter produces… D Day Show whether a target date is ahead of or behind a reference date using D− and D+ notation. This is a… Adult Total-Water Reference This tool shows a sex-based adult reference rather than a weight-based calculation. Total water includes… Data Size Converter | How to use and interpret results Expand a byte quantity into several sizes from bytes through TB. Switching the factor between 1000 and 1024… Date Calculator Use one mode to compare two dates and another to move a starting date by a day count. Distinguishing those… Days Between Dates — Inclusive Count, Free | How to use and interpret results Measure elapsed calendar days between two dates and view an equivalent week count. This distinguishes date… Days Until Date Calculator — Countdown Calculate remaining calendar days and an approximate number of weeks to a target date. A past target is… Decimal To Hex | How to use and interpret results Represent the same integer in decimal, binary, octal or hexadecimal notation. This converts one numeric… Decode JWT — Inspect Token, Local Inspect the JSON header and claims carried inside a JWT without treating their presence as proof of… Dedupe Lines — Unique Text, Free | How to use and interpret results Remove repeated lines while preserving the order of their first occurrence. Optional case-insensitive… Dice Roller Roll a chosen number of virtual dice and inspect both individual faces and the total. The output is useful… Diff Checker | How to use and interpret results Compare two texts as ordered lines and mark additions, removals and unchanged sections. A… Discount Calculator Calculate the saving and remaining price for one percentage discount. The additional tax-inclusive figure is… Domain Extractor | How to use and interpret results Collect domain-looking strings from longer text and reduce duplicates. Use it when host-name candidates are… Dream Interpreter Look up a light-hearted interpretation associated with a keyword from a dream. The tool selects prepared… Due Date from the Last Menstrual Period Calculate the date 40 weeks after the last menstrual period begins. ACOG explains this dating convention,… Dutch Pay | How to use and interpret results Add an optional tip to a total and divide it equally among participants. It suits shared meals where… Electricity Bill Model energy charges by splitting consumption into three bands with rates you supply. This is a transparent… Electricity Converter | How to use and interpret results Solve a resistive electrical model from two of voltage, current, resistance and power. A separate… Email Extractor Collect email-shaped strings from pasted text to create a contact-list draft. Matching is performed on the… Email Format Check | How to use and interpret results Check email candidates against a practical address-shape pattern and list the outcomes. An @ sign and a… Encode & Decode URL — Percent Encoding Percent-encode one URL component or recover its readable text. This is useful for a search-term value… Engineering Units | How to use and interpret results Compare one pressure, force or speed value in several units of the same quantity. Fixed factors connect… Excel To Table Turn spreadsheet clipboard text into an HTML table for an article. The input is delimited text, not a… Exif Remover | How to use and interpret results Repaint a photo onto a canvas and encode a new image file. This rebuilds pixels rather than editing the… Fahrenheit to Celsius Converter — Free Convert temperature readings between Fahrenheit, Celsius and kelvin. The conversion accounts for different… Eight-Item Fatigue Reflection Use eight original questions to organise fatigue experiences. This is not a validated medical fatigue scale… Favicon Generator | How to use and interpret results Create square 16-, 32- and 180-pixel PNG versions of a logo. A cover fit fills each square, which can crop… Feet to Meters Converter — Free Convert a length in feet to metres. The numeric field takes decimal feet, so six feet six inches is… Final Grade Calculator — Score Needed | How to use and interpret results Work backward from a desired course grade to the required final-exam score. The result tests a… Find & Replace Text — In Browser Replace a literal phrase or a regular-expression match in a block of text. Use the result and replacement… Format HTML — Pretty Print, Local | How to use and interpret results Indent a short HTML fragment using tag boundaries to make its structure easier to read. This is lightweight… Format JSON — Pretty Print, Local Parse JSON and display it with indentation or compact spacing. This helps inspect configuration data while… Format SQL — Pretty Print, Local | How to use and interpret results Insert line breaks around SQL keywords to make a short query easier to scan by clause. The tool uses… Fuel Cost Estimate fuel volume and cost from distance, fuel economy and a price per litre. The calculation supports… Fuel Economy | How to use and interpret results Calculate both kilometres per litre and litres per 100 kilometres from one trip. A larger km/L value and a… Gallons to Liters Converter — US Liquid Convert US liquid gallons to litres. The source unit matters: this gallon is not the imperial gallon used in… GCF and LCM Calculator — Two Integers | How to use and interpret results Find a greatest common factor for simplifying fractions and a least common multiple for shared repetition… Generate Password — Random, In Browser Generate a password candidate from selected character sets using the browser’s cryptographic random… Generate UUID — v4, Local, Free | How to use and interpret results Create multiple version-4 identifiers using the Web Crypto UUID generator. These random IDs suit test… Gitignore Generator Combine environment-specific patterns into a draft .gitignore. The output helps decide which untracked files… Golf Olympic | How to use and interpret results Sort player names and stroke totals from low to high and show a leaderboard. Despite its name, the… GPA Calculator Calculate a credit-weighted grade average using a selected 4.5 or 4.0 scale. The selected mapping supports… Grade Calculator — Weighted Scores, Free | How to use and interpret results Compute a weighted mean by summing score-times-weight and dividing by the total weight. Weights may add to… Gradient Generator Build a CSS linear gradient by adjusting colour stops and direction. The preview helps compare backgrounds,… Gyaru Moji | How to use and interpret results Replace selected Latin and Korean characters with decorative lookalikes for playful text. A local… Hangul Decompose / Compose Inspect a modern Hangul syllable as initial, medial and final components, or try composing supported jamo.… Hangul Particle Helper | How to use and interpret results Choose a Korean particle from pairs such as 은/는 by checking the final Hangul syllable found in the input. It… Hangul Keyboard Converter Map individual Latin keys to Korean two-set keyboard jamo and back. This is a keyboard-position reference,… Hash Generator | How to use and interpret results Calculate several hexadecimal digests of the input's UTF-8 bytes. Comparing fingerprints reveals text… Heading From HTML Extract H1 through H6 headings from HTML in document order. The outline can reveal an abrupt level change or… Sound-Cue Reaction Activity Measure the delay between an audible cue and a button press over five trials. This browser activity does not… Estimated Heart-Rate Training Zones Estimate maximum heart rate from age and divide it into percentage zones. Without a measured maximum or… HEX to RGB Converter — CSS Colour | How to use and interpret results Decode a three- or six-digit CSS HEX colour into red, green and blue channel values. Each pair of… Hours Between Times — Overnight OK, Free Find the interval between two clock times for a same-day or overnight schedule. The form is suited to a… Hours to Decimal Calculator — Timecard | How to use and interpret results Convert hours and minutes into decimal hours. This is useful when a time-entry system expects 1.5 rather… Hreflang Generator Create HTML hreflang link tags from language and URL pairs. These tags describe real alternate-language… HTML Editor | How to use and interpret results Inspect an HTML draft inside a preview frame to see its visual structure. Unlike a formatter, the central… HTML Entity Converter Convert HTML-sensitive characters to references or decode supported references back to text. Use it to… HTML Formatter | How to use and interpret results Split HTML at tag boundaries and indent it with two spaces per level. Void elements such as br and img are… HTML Meta Builder — Tags, Free Prepare head markup from a title, description, canonical address and image value. The builder is useful for… HTML to Markdown | How to use and interpret results Convert HTML headings, paragraphs, emphasis, links and lists into a Markdown draft. The aim is editable… HTML Validator Run a lightweight tag-pair check to spot possible nesting mistakes in HTML. This is a quick editing aid… Htpasswd Generator | How to use and interpret results Produce a username-and-hash line in an Apache htpasswd-compatible style. The available legacy hash methods… HTTP Status Codes Look up HTTP status numbers, categories and explanations in an embedded reference. Use it while reading a… Devine Height-Based Reference Weight Calculate a Devine reference using height and an equation sex coefficient. Since current weight, body… Image Color Picker | How to use and interpret results Read RGB and HEX values at a clicked point on an image canvas. Sampling follows the displayed working image… Image Compressor Re-encode an image as JPEG or WebP in the browser and compare the resulting size and appearance. Pixel… Image Crop | How to use and interpret results Crop a rectangular region by its top-left coordinates, width and height, then save it as PNG. Numeric pixel… Image Grayscale Apply a grayscale or sepia effect and save the result as PNG. The preview is intended for visual treatment,… Image Resizer | How to use and interpret results Change an image's pixel dimensions and export a PNG. With aspect-ratio lock enabled, height follows width to… Image Rotate Rotate an image in ninety-degree steps or flip it horizontally or vertically, then save a PNG. The controls… Image to Base64 | How to use and interpret results Read image bytes as a copyable data URL for embedding experiments. It can help with small icons but neither… Invisible Char Remover Remove a selected set of hard-to-see spacing and control characters from pasted text. This can help inspect… IPv4 CIDR Calculator — Subnet, Free | How to use and interpret results Calculate an IPv4 network, mask and address range from an address and prefix length. This explains bit… IPv4 to IPv6 View an IPv4 address in IPv4-mapped IPv6 notation. The conversion illustrates an address representation; it… IQ Fun Test | How to use and interpret results Answer eight short sequence, logic and geometry questions and inspect the number correct. IQ in the activity… JS/CSS Formatter Apply simple indentation and line breaks around braces and semicolons. Because this formatter does not fully… JS/CSS Minifier | How to use and interpret results Reduce comments and selected whitespace with text rules for a JavaScript or CSS draft. This differs from an… JSON Encoder Represent plain text as a JSON string or parse a JSON value into a readable result. The view is useful for… JSON Formatter | How to use and interpret results Parse JSON and output either a two-space indented or compact representation. It helps spot syntax problems… JSON-LD Generator Prepare JSON-LD for an Article, Organization or FAQPage from supplied fields. The output describes facts… JSON to CSV | How to use and interpret results Collect keys across a JSON array of objects to build CSV columns. A property that appears only in a later… JSON to Rows — CSV Table, Free Export JSON object values as rows and columns of CSV text. This supports moving simple records into a table… JSON to YAML | How to use and interpret results Serialize JSON objects, arrays and scalar values into an indented YAML draft. The input is strict JSON and… JWT Decoder Split a token and inspect its Base64url header and payload as JSON. The view helps debug claim formatting… Keyboard Tester | How to use and interpret results Observe keyboard events reaching the browser, including the last key and Caps Lock state. This visual check… kg to lb Converter — Kilograms to Pounds Compare kilograms, pounds and supported mass units using fixed conversion factors. This is useful for… Kilometers to Miles Converter — Free | How to use and interpret results Express a distance in kilometres as statute miles. Use it to compare route lengths or workout distances… Korean Romanizer Draft a Latin-letter rendering by mapping modern Hangul syllable components through an embedded table. The… km/h to MPH Converter — Speed Pair | How to use and interpret results Convert kilometres per hour to miles per hour. The abbreviation kph is used here for the same speed unit as… Latex Preview Preview LaTeX-style mathematics through KaTeX to check symbols, superscripts and layout. The tool typesets… Length Converter | How to use and interpret results Expand one length into metres, feet, inches, miles, nautical miles and other units. Separate mile and… Length Units Converter — Free Online Convert a linear measurement between supported units using fixed international factors. Input and output… Link From HTML | How to use and interpret results Collect href and src attribute values from pasted HTML and deduplicate each group. It extracts link and… List Sorter Sort, reverse, deduplicate or shuffle a line-based list. Each complete line is an item, so words within a… Liters to Gallons Converter — US Liquid | How to use and interpret results Convert litres into US liquid gallons. This helps compare a metric container label with a US-volume… Lorem Generator — Placeholder Text, Free Generate Lorem Ipsum paragraphs to test the height and flow of a text region. The output is layout filler… Lorem Ipsum Generator | How to use and interpret results Generate Korean or English placeholder sentences and paragraphs for a layout mockup. Random combinations… Lottery Draw entries from a list or integers from a chosen range for a casual game or order selection. This random… Lotto Generator | How to use and interpret results Shuffle integers from 1 through 45 and select six distinct numbers per sorted line. This local random-choice… Love Quotient Test Answer a light-hearted questionnaire that totals preset points and selects a relationship-style description.… Lucky Interior | How to use and interpret results Map a birth date's local day-cycle calculation to a table of element-themed colours and materials. The… Lucky Style View a prepared colour and style suggestion selected from an internal date category. Treat it as a playful… Lunar Converter | How to use and interpret results Convert Gregorian dates and lunar year, month, day and leap-month fields with a bundled lunisolar table.… Markdown Preview Preview simple Markdown as HTML to inspect headings and list placement. The lightweight converter uses its… Markdown Table Generator | How to use and interpret results Build a pipe-style Markdown table from pasted tab/comma-separated data or an editable grid. The first row… Markdown to HTML Convert Markdown copy into an HTML fragment that can be pasted into an editor. The output assists with… Markdown TOC | How to use and interpret results Find hash-prefixed Markdown headings and make nested table-of-contents links. It helps review a long… Mass Units Converter — kg, lb, Free Convert a mass from one selected unit into another. This pairwise view is useful when reconciling grams on… MBTI Test | How to use and interpret results Count twelve paired-choice answers in four groups to display a four-letter preference label. This local… Meme Maker Place short captions at the top and bottom of an image and save a PNG meme. The words are composited into… Memory Test | How to use and interpret results Recall a briefly displayed digit string, starting with three digits and growing after each correct answer.… Menstrual Cycle Calendar Arithmetic Use an assumed constant cycle to calculate a next-period date and an ovulation window. This is not ovulation… Mermaid Preview Preview a Mermaid diagram as SVG from its textual definition. This supports maintaining nodes and… Meta From HTML | How to use and interpret results Extract title, description, robots and canonical values from pasted HTML. The input is an acquired source… Meta Tag Generator Build search-description and social-sharing tags from titles, descriptions and an image URL. You can draft a… Mileage Value | How to use and interpret results Divide a cash price by required miles to compare a simple KRW-per-mile redemption ratio. It evaluates… Miles to Kilometers Converter — Free Express a distance in statute miles as kilometres. Use it for mileage logs or course lengths that need a… Military Time Converter — 24 Hour Clock | How to use and interpret results Read a numeric clock value such as 1845 in both 24-hour and 12-hour notation. This is a notation conversion… Mime Lookup Look up an embedded MIME mapping for a file extension. The reference can help draft server settings or… MPH to km/h Converter — Speed Pair | How to use and interpret results Convert a speed in miles per hour to kilometres per hour while retaining the per-hour meaning of the… My IP Address Ask an external IP service which public address it observes for the current connection. This helps… Name Generator | How to use and interpret results Combine built-in adjective, noun and role words into draft character or game names. Korean, English and… Number Base Express an integer in a selected base such as binary, octal, decimal or hexadecimal. This is useful for… Number to Korean | How to use and interpret results Spell a nonnegative KRW integer using Korean units such as 만, 억 and 조. The English interface still produces… OG Image Generator Create a 1200-by-630-pixel sharing image from a title, subtitle and colours. The tool prepares an Open Graph… Compare One-Rep Max Equations Compare two estimated one-repetition maxima from a completed weight and rep count. These are mathematical… Quick 1RM Estimate in Kilograms Use kilograms and a repetition count to inspect two empirical 1RM estimates. This short form explains… Online Clock | How to use and interpret results Display the device's current date, weekday and time in a large clock. It does not query a server or national… Ovulation Calculator — Free, Private Project an assumed ovulation date from a period start and cycle length. The form does not measure ovulation… Running Pace Calculator — km or mi, Free | How to use and interpret results Find pace from distance and elapsed time, or estimate finish time from a chosen pace. Per-kilometre and… Paint Calculator Estimate paint containers from area, coat count and coverage per container. The result supports a basic… Paint Coverage Calculator — Litres Needed | How to use and interpret results Estimate paint volume from area, coat count and the product's coverage per litre. Compare litres, US gallons… Parking Fee Model a parking charge from a base period and fee plus additional billing intervals. Supply a tariff you… Password Generator | How to use and interpret results Generate a password from chosen character pools using random selections. Each enabled pool contributes at… Password Strength Score password length and composition with embedded rules to obtain improvement hints. Treat the output as a… Password Strength Meter — Local Check | How to use and interpret results Estimate entropy and a strength band from string length and character-pool size. It is a combinations model… PDF To Image Render PDF pages in the browser and save them as PNG or JPEG images. This is useful for sharing a page as a… Percent Calculator | How to use and interpret results Calculate a percentage of a value, one value as a share of another, or change from an earlier value.… Pet Age Express a dog’s or cat’s age as a human-age analogy using an internal piecewise model. The comparison can… Phone Subsidy Penalty | How to use and interpret results Show a legacy subsidy-return approximation from the subsidy and months used. Its fixed 24-month term and… Placeholder Image Generate a temporary image with chosen pixel dimensions, colours and a label. Use it to test a layout’s… Png Transparent | How to use and interpret results Make pixels transparent when their RGB channels are close to a clicked colour. This is colour-threshold… Power Converter Convert rated power among watts, kilowatts, horsepower and other supported units. The comparison concerns… Power Units Converter — W, HP, Free | How to use and interpret results Convert power among watts, kilowatts, megawatts and mechanical horsepower. Different horsepower definitions… Due Date and Gestational Age Today Display both an estimated due date and today’s gestational age from the first day of the last period. This… Gestational Weeks on a Chosen Date Check gestational age on a chosen date rather than only today. This calendar counts from the last menstrual… Protein from a Chosen Grams-per-Kilogram Factor Choose a protein-per-body-weight factor to calculate daily grams. Activity labels are simplified selection… Punycode Converter View an internationalized domain as the ASCII hostname produced by the browser’s URL parser. This checks its… px to rem Converter — CSS, Free | How to use and interpret results Divide a pixel length by a supplied root font size to express it in rem. The tool does not inspect a page's… Pyeong Converter Convert square metres and pyeong using a practical approximation, or calculate a rectangle from width and… Pyeong to m² Converter — Korea Area | How to use and interpret results Convert an area stated in Korean pyeong to square metres. The tool changes units for the same area; it does… QR Code Reader Read the text contained in a QR code from an image or an authorized camera feed. Inspecting the decoded… QR Code Generator | How to use and interpret results Encode text or a URL into a QR image and save a PNG. The library uses error-correction level M, without… Radiation Converter Convert radiation-related units within the same physical quantity. Sievert-based and gray-based groups… Base Converter — Binary, Octal, Decimal, Hex | How to use and interpret results Convert integer digit strings among binary, octal, decimal and hexadecimal. Every digit is checked against… Random Data Generator Generate sample rows with names, email-shaped values and identifiers for development. Export JSON, CSV or… Reaction Test | How to use and interpret results Record five intervals between a colour change and a click, then show mean, fastest and slowest milliseconds.… Reading Time Calculator — WPM, Free Estimate reading time from whitespace-delimited words and an entered words-per-minute rate. The figure… Regex Playground — Test Patterns, Free | How to use and interpret results Apply a JavaScript regular expression and flags to a short test string, showing match contents and… Regex Tester Test a JavaScript regular expression against text and inspect match positions and capture groups. This shows… Remove Duplicate Lines | How to use and interpret results Keep the first occurrence of each repeated line and count removals. A separate trim option lets you decide… Repeat Timer Repeat an equal-duration interval while displaying the current round and remaining time. The tool can… RGB to HEX Converter — CSS Colour | How to use and interpret results Assemble red, green and blue values from 0 through 255 into six-digit HEX notation. It helps transfer… Right Triangle Calculator — Pythagoras Solve one unknown side of a right triangle using the Pythagorean relationship. Side c is the hypotenuse; a… robots.txt Builder — Free, Local | How to use and interpret results Draft a robots.txt group from User-agent and Allow/Disallow paths. The result is crawler guidance text, not… Robots Txt Generator Create a draft robots.txt from a user-agent name and allowed or disallowed paths. The output expresses… Roman Numeral | How to use and interpret results Convert integers from 1 to 3999 into conventional Roman numerals and back. Subtractive forms such as IV and… Roman Numerals Converter — Free Convert positive integers to Roman notation and interpret supported Roman numerals. The comparison is useful… Roof Pitch Calculator — Rise Over Run | How to use and interpret results Calculate slope, angle and a sloping-length multiplier from rise and horizontal run. This is geometry rather… Rows to JSON — CSV In Browser Convert CSV rows into a JSON object array using the first row as property names. This helps inspect a small… Running Pace | How to use and interpret results Calculate per-kilometre pace and average speed from kilometres and separate hour/minute/second fields.… Saju Calculator View a four-pillars-style result from an internal stem-and-branch calculation for entertainment. Solar-term… Saju Compat | How to use and interpret results Compare two dates through a local day-stem and element table to produce an entertainment score. It does not… Samjae Check Look up a samjae category by matching a birth-year animal group to an internal cycle table. The result… Scientific Calculator | How to use and interpret results Evaluate parentheses, powers, square roots, logarithms and trigonometric functions with a restricted… Screen Size Estimate a rectangular screen’s width and height from its diagonal and aspect ratio. This compares the… Select Agreement Penalty | How to use and interpret results Apply a fixed discount rate to monthly price, contract length and months used in a legacy penalty model. It… Sitemap Generator Build an XML sitemap from a supplied URL list and save the result. This is for an operator who already knows… Bedtime Candidates from Wake Time Build a timetable by subtracting fixed sleep blocks and a falling-asleep allowance. NHLBI describes cycles… Compare Bedtimes by Fixed Sleep Blocks Compare candidate bedtimes by dividing sleep into fixed 90-minute blocks. This is a clock-planning exercise… Slug Generator | How to use and interpret results Turn a title into a lowercase, hyphen-oriented URL segment. Local modes strip Hangul, approximate… Sonless Day List dates in a selected month that match an internal heavenly-stem rule. The current rule differs from the… Sort Text Lines — A–Z, In Browser | How to use and interpret results Sort text lines with direction, case-insensitive comparison and trimming options. Character-order comparison… Special Chars Pick and copy characters from built-in groups such as punctuation, arrows, mathematics and currency. This… SQL Formatter | How to use and interpret results Uppercase recognized SQL keywords and insert breaks around clauses and commas. This rule-based readability… Square Footage Calculator — ft² and m² Multiply a rectangle’s length and width and show both square feet and square metres. The tool suits a simple… Square Metres to Pyeong Converter | How to use and interpret results Read an area in square metres as Korean pyeong. Keep the source’s area category intact while changing the… SSL PEM Viewer Inspect a PEM block or OpenSSL text output for its format and selected certificate details. The viewer helps… Stopwatch | How to use and interpret results Accumulate elapsed time and record lap-button moments. Each lap is a cumulative timestamp since the start,… Two-Week Stress Reflection Reflect on the last two weeks with eight original questions. This is not the validated PSS or a clinical… String Escaper Make backslashes, quotes and control characters visible as escapes, or restore supported escape sequences.… Strip Invisible Chars — Clean Text, Free | How to use and interpret results Remove selected zero-width characters, bidi controls, BOM and soft hyphen from text. It helps investigate… Adult TDEE by Activity Factor Estimate daily expenditure by multiplying adult resting energy by an activity factor. This is neither an… Team Divider Shuffle participant entries and distribute them across teams, optionally selecting a leader. The tool helps… Temperature Converter — C, F, K, Free | How to use and interpret results Convert among Celsius, Fahrenheit and Kelvin from any selected starting scale. This helps compare laboratory… Teto Egen Test Count answers in two playful teto and egen categories and display a style description. The quiz explores a… Text Case Converter — Title, UPPER, Free | How to use and interpret results Change English text to uppercase, lowercase, token-title or sentence-style casing. It is a quick formatting… Text Cleaner Normalize line endings, trim line edges, collapse repeated spaces or remove blank lines through separate… Text Diff — Compare Lines, Local | How to use and interpret results Compare text lines and produce a diff with plus additions and minus removals. An 800-line-per-side cap keeps… Text Replacer Replace all literal matches or all matches of a JavaScript regular expression and inspect the replacement… Text To Ascii | How to use and interpret results Expand text into Unicode code points in decimal, hexadecimal or both. Despite the ASCII name, Korean… Text To Decimal Display text as decimal Unicode code points for character-encoding study or inspection. The numbers identify… Text To Hex | How to use and interpret results Convert a string to hexadecimal UTF-8 bytes or decode those bytes as text. This exposes encoding order… Timer Alarm Count down an entered number of minutes and seconds, then update the display and optionally play a tone.… Timestamp Converter | How to use and interpret results Convert Unix seconds or milliseconds to a local date/time and back. UTC ISO and local displays let you… Timezone Offset Calculator — Free Display one instant in two IANA time zones and compare their UTC offsets. This helps coordinate… Today Fortune | How to use and interpret results Feed a birth year and date into a local hash rule to produce four playful scores. Labels such as love, money… Unicode Converter Express text as U+ code points, decimal values or Unicode escapes and restore supported notation. This helps… Unit Converter | How to use and interpret results Convert four common pairs: centimetres/inches, metres/feet, kilograms/pounds and Celsius/Fahrenheit.… Unix chmod Helper — Permissions, Free Translate owner, group and other read/write/execute selections into octal and symbolic permissions. The… Unix Timestamp Converter — Free | How to use and interpret results Produce Unix seconds, an ISO UTC string and a device-local string from now, a Unix value or ISO input. This… URL Encoder / Decoder Encode text as a URL component or decode percent notation and form-style plus signs. The controls help… URL Opener | How to use and interpret results Attempt to open multiple web addresses in new tabs. Unlike a text converter, running it visits destinations,… URL Params Editor Edit query parameters as key/value rows and rebuild a URL after additions or removals. This makes the… URL Parser | How to use and interpret results Separate an address into protocol, host, port, path, query and fragment. The output follows browser URL… URL Slugify — SEO-Friendly Slugs, Free Turn an English phrase into an ASCII lowercase, hyphen-separated URL slug. The process applies NFKD… User-Agent Info | How to use and interpret results Collect browser-exposed user-agent, language, cookie and viewport information into JSON. It supports… Username Generator Combine a keyword with prefixes, suffixes and numbers to suggest usernames. The generator supports… UTM Builder | How to use and interpret results Append campaign source, medium and name plus optional term/content values to a destination URL. It prepares… UTM Link Builder — Campaign URLs, Free Append campaign-source, medium, name and optional UTM values to a base URL. The builder creates a tagged… UUID Generator | How to use and interpret results Generate UUID v4 values from browser cryptographic randomness with uppercase and hyphen display options. A… Volume Area Units Compare pyeong, square metres and the site-trade term hebe for area. Despite the tool name mentioning… Waist-to-Hip Ratio with Measurement Context Calculate waist divided by hip circumference, a dimensionless ratio. WHO’s report considers measurement… Water Bill | How to use and interpret results Multiply usage by user-entered water, sewer and levy rates, then total the components. This linear estimate… Weight Times a Water Factor Multiply body weight by a user-selected water factor. The default 33 is not an individually validated… WCAG Contrast Checker Calculate contrast from foreground and background relative luminance and compare AA/AAA thresholds for… Web Calculator | How to use and interpret results Evaluate an expression containing numbers, operators, parentheses and allowed Math functions. Enter the… Webp Converter Re-encode a browser-readable image as WebP and compare input and output sizes. This creates a web-delivery… Week Number | How to use and interpret results Find a Monday-start week number, its week-year, and the Monday/Sunday boundaries. Around New Year, a date's… Weight Converter Compare kilograms, grams, pounds, ounces and several ton definitions in one view. The output helps interpret… Work Days Calculator — Skip Weekends, Free | How to use and interpret results Count Monday-through-Friday dates in an inclusive range. Working days here means weekends excluded, without… World Clock View the current date and time for several cities alongside their IANA zone names. The clock supports quick… XML Formatter | How to use and interpret results Parse XML with the browser and rewrite elements using two-space indentation. Syntax errors can be shown, but… Convert XML to JSON and JSON to XML Map XML into JSON using local representation rules, or draft XML from JSON. The conversion helps compare… YAML to JSON | How to use and interpret results Convert a basic indentation-based YAML draft into JSON with a small built-in parser. It is not a general… Zodiac Animal Assign an animal from a twelve-year cycle using a Gregorian year number. The lookup illustrates the year…