Free Web Tools
A growing set of fast, private utilities that run entirely in your browser — what you enter never leaves your device. Built by Patrick Bushe.
Ndjson To JSON Array
Convert newline-delimited JSON into a JSON array for fixtures and examples. Three event records can become a bracketed array for a test fixture.
Open ToolNewsletter Sponsor Revenue Calculator
Estimate newsletter sponsorship revenue from subscribers and a sponsor CPM. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolNginx Location Block
Work with nginx location block in your browser with a live preview and one-click copy — free and private, generated locally in your browser with no upload and.
Open ToolNihilist Cipher
Free Nihilist cipher adds repeating keyed Polybius numbers and reverses the numeric sums. Runs in your browser; no uploads or accounts are used.
Open ToolNpm Package JSON Exports
Generate package.json exports maps for ESM, CJS, and type declaration entries. Free and private in your browser, with nothing uploaded and no account.
Open ToolNumeric Derivative Calculator
Free numeric derivative calculator using a central difference for common functions at any x value and positive step size, directly in your browser.
Open ToolOhm’s Law Calculator
Free Ohm’s law calculator: enter any two of voltage, current, and resistance to find the third plus power, computed locally in your browser.
Open ToolOil Change Mileage Calculator
Calculate the next oil-change odometer from the current reading and an interval. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolOne Rep Max Comparison
Compare Epley, Brzycki, and Lombardi one-rep max estimates from lifted weight and reps. It runs entirely in your browser — no uploads or accounts.
Open ToolOne-Rep Max Calculator
Free one-rep max calculator using the Epley and Brzycki formulas, with percentage training loads, all computed privately in your browser.
Open ToolOpen Graph Card
Preview Open Graph title, description, image URL text, and site name as a social card mockup. Free and private in your browser, with nothing uploaded.
Open ToolOrbital Velocity Calculator
Free orbital velocity calculator that estimates ideal circular-orbit speed. Review labeled assumptions and a worked result calculated privately in your browser.
Open ToolOven Temperature Converter
Free oven temperature converter: switch between Celsius, Fahrenheit, and gas mark, computed locally in your browser.
Open ToolOvertime Pay Calculator
Free overtime pay calculator: work out total pay from regular and overtime hours and a multiplier, in your browser.
Open ToolOvulation Window Calculator
Estimate ovulation day and fertile window from the first day of your last period and your cycle length. It runs entirely in your browser — no uploads or accounts.
Open ToolPassphrase Generator
Free diceware-style passphrase generator: build memorable multi-word passphrases from a built-in list using secure randomness, all in your browser.
Open ToolPastel Color Generator
Free pastel color generator: create soft, random pastel color palettes with hex codes, in your browser.
Open ToolPaver Base Calculator
Calculate paver base bags from area, depth, bag volume, and waste. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolPayload Remaining Calculator
Calculate remaining and used payload from a rating and a used percentage. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolPDF to Images
Convert each page of a PDF to a PNG image in your browser at your chosen scale, then download them. Your document is never uploaded to a server.
Open ToolPendulum Period Calculator
Free pendulum period calculator with labeled inputs and an immediate result. It estimates the small-angle pendulum period privately in your browser.
Open ToolPercent of a Number Calculator
Free percent of a number calculator: find what a percentage of a number is, computed locally in your browser.
Open ToolPercentage Decrease Calculator
Free percentage decrease calculator: find the percent drop from one value to another, computed in your browser.
Open ToolPercentage Increase Calculator
Free percentage increase calculator: find the percent growth from one value to another, computed in your browser.
Open ToolPercentile Calculator
Free percentile calculator: find the value at any percentile of a data set by interpolation, in your browser.
Open ToolPermissions Policy
Build Permissions-Policy header snippets for camera, microphone, geolocation, and payment. Free and private in your browser, with nothing uploaded.
Open ToolPersonal Loan Calculator
Calculate personal loan payment, finance charge, and total repayment from amount, APR, and months. It runs locally in your browser with no uploads.
Open ToolpH Calculator
Free pH calculator: convert between hydrogen ion concentration and pH, with pOH, computed locally in your browser.
Open ToolPlaceholder Image Generator
Free placeholder image generator: create sized placeholder images with custom colors and text, downloadable as PNG, in your browser.
Open ToolPlate Loading Calculator
Calculate plates per side for a barbell target weight from bar weight and available large plates. It runs entirely in your browser, with no uploads or accounts.
Open ToolPlaying Card Drawer
Draw random playing cards without replacement from a standard 52-card deck, track what remains, and reset the deck locally in your browser without uploads.
Open ToolPoisson Probability Calculator
Free Poisson probability calculator: find the chance of k events given an average rate, in your browser.
Open ToolPond Volume Calculator
Calculate pond gallons from length, width, average depth, and shape factor. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolPool Volume Calculator
Free pool volume calculator: find the gallons in a rectangular pool from its size and average depth, in your browser.
Open ToolPorta Cipher
Free Porta cipher applies reciprocal paired-alphabet substitutions with an alphabetic keyword. Runs in your browser; no uploads or accounts are used.
Open ToolPortfolio Rebalance Calculator
Calculate target dollars and buy or sell amounts from total portfolio value and allocation percent. It runs locally in your browser with no uploads.
Open ToolPosition Size Risk Calculator
Calculate shares or units from account size, risk percent, entry price, and stop price. It runs entirely in your browser — no uploads or accounts.
Open ToolPPM Converter
Free PPM calculator: convert between parts per million, percent, and mg/L, computed locally in your browser.
Open ToolPresent Value Calculator
Free present value calculator: find what a future sum is worth today at a given discount rate and time, computed locally in your browser.
Open ToolPressure Converter
Free pressure converter that converts values instantly in your browser. Includes examples, formulas, limits, copy-ready output, and local privacy.
Open ToolPrice-to-Earnings Ratio Calculator
Free P/E ratio calculator: find a stock’s price-to-earnings ratio from price and earnings per share, in your browser.
Open ToolPrime Number Checker
Free prime number checker: test whether a number is prime, see a factor if it is not, and find the next prime — all locally in your browser.
Open ToolProportion Confidence Interval
Free proportion confidence interval with labeled inputs and an immediate result. It estimates a z interval around a sample proportion privately in your browser.
Open ToolProportion Margin of Error
Free proportion margin of error with labeled inputs and an immediate result. It calculates a z-based proportion margin of error privately in your browser.
Open ToolProtein Calculator
Free protein calculator: find how many grams of protein you need a day from your body weight and training goal, computed privately in your browser.
Open ToolProtobuf Field Number Planner
Plan protobuf field number in your browser with a live preview and one-click copy — free and private, generated locally in your browser with no upload and no.
Open ToolPyramid Volume Calculator
Free pyramid volume calculator: find the volume of a square pyramid from base and height, in your browser.
Open ToolQr Link Card
Create a text-based QR landing card with URL, title, note, and tracking fields. Free and private in your browser, with nothing uploaded and no account.
Open ToolQuadratic Factoring Calculator
Free quadratic factoring calculator that finds real roots and writes a polynomial as linear factors from a, b, and c entirely in your browser.
Open ToolQuantity Discount Calculator
Free quantity discount calculator: find the total and effective unit price after a bulk discount, in your browser.
Open ToolQuarter Calculator
Free calendar quarter calculator: find which quarter a date is in, plus days elapsed and remaining, computed locally in your browser.
Open ToolQuartile Calculator
Free quartile calculator: find Q1, Q2, Q3, and the interquartile range of a data set, in your browser.
Open ToolQuiz Curve Points Calculator
Calculate a curved score by adding curve points to a raw score. Everything is computed locally in your browser, with no uploads and no sign-ups.
Open ToolRaffle Expected Winners Calculator
Calculate expected winners from a ticket count and a win rate. Everything is computed locally in your browser, with no uploads and no sign-ups.
Open ToolRain Barrel Yield Estimator
Estimate rainwater harvest from roof area, rainfall inches, and collection efficiency. It runs entirely in your browser — no uploads or accounts.
Open ToolRaised Bed Soil Calculator
Free raised bed soil calculator with labeled inputs and an immediate result. It calculates soil volume for a rectangular bed privately in your browser.
Open ToolRamp Slope Calculator
Free ramp slope calculator with labeled inputs and an immediate result. It reports rise-to-run ratio, grade, and angle privately in your browser.
Open ToolRandom Color Generator
Free random color generator: draw a random color with its hex and RGB values and a live swatch, generated in your browser.
Open ToolRandom Letter Generator
Free random letter generator: draw random letters of the alphabet in upper or lower case, generated in your browser.
Open ToolRandom Name Picker
Free random name picker: enter a list and draw one winner fairly, with a quick spin animation, all in your browser.
Open ToolRandom Table Range Calculator
Calculate how many die rolls cover a random table from entries and die faces. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolRandom Team Generator
Free random team generator: split a list of names into balanced random teams, computed locally in your browser.
Open ToolRC Time Constant Calculator
Free RC time constant calculator: find the time constant and cutoff frequency from resistance and capacitance, in your browser.
Open ToolREADME Badge Generator
Free README badge generator that encodes a label, message, color, logo, style, and target into Markdown and HTML with encoded paths in your browser.
Open ToolReal Interest Rate Calculator
Free real interest rate calculator with labeled inputs and an immediate result. It adjusts a nominal rate for inflation privately in your browser.
Open ToolRebar Spacing Calculator
Estimate rebar line count and total length for a slab grid from dimensions and spacing. It runs entirely in your browser — no uploads or accounts.
Open ToolRecipe Hydration Calculator
Calculate water weight from flour weight and a hydration percentage. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolReduced Motion Safe CSS
Build reduced motion safe CSS in your browser with a live preview and one-click copy — free and private, generated locally in your browser with no upload and.
Open ToolReference List Builder
Build a printable professional reference page from repeatable reference fields, relationship notes, contact details, and resume header in your browser.
Open ToolReferrer Policy
Choose a Referrer-Policy value and preview the header plus matching meta tag. Free and private in your browser, with nothing uploaded and no account.
Open ToolRefund Policy Generator
Create a refund and return policy with store name, refund window, product type, return conditions, contact details, and copyable output in your browser.
Open ToolRegex Capture Group Tester
Test regex capture group in your browser with a live preview and one-click copy. It runs entirely client-side, so nothing is uploaded and no account is needed.
Open ToolRegex Replace
Test a regular expression replacement and preview the transformed text. A slug cleanup can replace repeated spaces and underscores with a single hyphen.
Open ToolRelative Risk Calculator
Free relative risk calculator from two cohort event tables, returning both group risks, risk ratio, and risk difference privately in your browser.
Open ToolRemove Emojis
Free emoji remover: strip emojis and pictographs from text, leaving clean plain text, computed in your browser.
Open ToolRemove Empty Lines
Free empty line remover deletes blank and whitespace-only rows while preserving text rows exactly. Runs in your browser; no uploads or accounts are used.
Open ToolRemove Numbers from Text
Free number remover deletes ASCII digits zero through nine while preserving all other text. Runs in your browser; no uploads or accounts are used.
Open ToolReorder Point Calculator
Free reorder point calculator: find the stock level at which to reorder, including safety stock, in your browser.
Open ToolRepeated Phrase Finder
Free repeated phrase finder counts recurring two-word through six-word sequences in text. Runs in your browser; no uploads or accounts are used.
Open ToolResume Builder
Build a clean resume from contact, summary, experience, education, and skills fields with live preview, copy output, and printing in your browser.
Open ToolResume Keyword Matcher
Compare resume text with a job description, find missing important keywords, and estimate a simple local match percentage for tailoring in your browser.
Open ToolRevenue Per Employee Calculator
Calculate revenue per employee from annual revenue and headcount. Everything is computed locally in your browser, with no uploads and no sign-ups.
Open ToolReverse DNS Pointer Generator
Free reverse DNS pointer generator that converts IPv4 and IPv6 addresses into in-addr.arpa and nibble-reversed ip6.arpa names in your browser.
Open ToolReverse List Order
Free reverse list tool: flip the order of lines in a list so the last becomes first, in your browser.
Open ToolReview Request Email Builder
Free review request email builder that creates polite timing, context, and direct-link drafts for customer review asks. Runs locally in your browser for...
Open ToolRice Grams to Cups Converter
Convert dry white rice grams to US cups and cups to grams using a 185-gram kitchen convention, with practical results calculated in your browser.
Open ToolRing Size Converter
Free ring size converter that converts values instantly in your browser. Includes examples, formulas, limits, copy-ready output, and local privacy.
Open ToolRoad Trip Cost Calculator
Free road trip cost calculator: split fuel costs for a round trip among passengers, computed locally in your browser.
Open ToolRobots Txt Rule Tester
Test robots txt rule in your browser with a live preview and one-click copy. Free and private: everything is generated locally in your browser with no upload.
Open ToolRoofing Calculator
Free roofing calculator: estimate roofing squares and shingle bundles from roof area and waste percent, calculated locally in your browser.
Open ToolROT13 Caesar Cipher
Free rot13 caesar cipher for cleaning, transforming, and checking pasted text. Process content locally in your browser without uploads.
Open ToolROT47 Converter
Free ROT47 converter: transform printable ASCII with the self-reversing ROT47 cipher, computed locally in your browser.
Open ToolRoute Transposition Cipher
Free route transposition cipher fills rows and reads a clockwise spiral through the grid. Runs in your browser; no uploads or accounts are used.
Open ToolRSS Item
Work with RSS item in your browser with a live preview and one-click copy. Free and private: everything is generated locally in your browser with no upload.
Open ToolRunning Pace Calculator
Free running pace calculator: convert distance and time into pace per km and mile plus speed, computed locally in your browser.
Open ToolSAFE Note Calculator
Estimate SAFE conversion shares from investment, valuation cap, discount, and priced round valuation. It runs locally in your browser with no uploads.
Open ToolSalary to Hourly Calculator
Convert annual salary to hourly, weekly, and monthly equivalents from hours per week and weeks worked. It runs locally in your browser with no uploads.
Open ToolSales Commission Calculator
Free sales commission calculator: work out commission and total pay from sales and a rate, in your browser.
Open ToolSand Calculator
Calculate sand volume and weight from area, depth, and density using manual project inputs. It runs entirely in your browser, with no uploads or accounts.
Open ToolSavings Rate Calculator
Free savings rate calculator: find what percentage of your income you save, and a rough years-to-goal, computed locally in your browser.
Open ToolSchema Markup Generator
Create simple FAQPage, SoftwareApplication, or Organization JSON-LD locally.
Open ToolSchema Organization Contactpoint
Build schema organization contactpoint in your browser with a live preview and one-click copy — free and private, generated locally in your browser with no.
Open ToolSchema QA Helper
Create a schema QA checklist for reviewing structured data before publishing.
Open ToolSchema Videoobject
Build schema videoobject in your browser with a live preview and one-click copy. It runs entirely client-side, so nothing is uploaded and no account is needed.
Open ToolScope Creep Response Generator
Draft polite scope creep responses that protect boundaries and offer next steps.
Open ToolScrabble Score Calculator
Free scrabble score calculator that totals standard English Scrabble letter values, with a specific worked example and private local processing in your browser.
Open Toolsecond to minute Converter
Free second to minute converter with exact factors, reverse conversion, copy-ready output, and a quick reference table that runs in your browser.
Open ToolSecurity Headers Checklist
Build a security headers checklist from selected policies and copy a starter block. Free and private in your browser, with nothing uploaded and no account.
Open ToolSemester Credit Load Calculator
Calculate total semester credits from a course count and credits each. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolSemver Range Tester
Free semver tester: check whether a version satisfies a range like ^1.2.0 or >=1.0.0, evaluated locally in your browser.
Open ToolSentence Length Analyzer
Free sentence length analyzer lists per-sentence word counts and computes the mean length. Runs in your browser; no uploads or accounts are used.
Open ToolSEO Slug Generator
Turn titles, headings, and product names into clean lowercase URL slugs.
Open ToolSepia Photo Filter
Free sepia photo filter: give any image a warm vintage sepia tone and download it, in your browser.
Open ToolSeries & Parallel Resistance
Free resistance calculator: paste resistor values to get the total in series and in parallel at once, computed locally in your browser.
Open ToolSerp Title Ab Tester
Test serp title ab in your browser with a live preview and one-click copy. Free and private: everything is generated locally in your browser with no upload.
Open ToolSHA-1 Hash Generator
Free sha-1 hash generator that generates a lowercase SHA-1 digest from UTF-8 text, with a specific worked example and private local processing in your browser.
Open ToolShelf Board Count Calculator
Calculate shelf boards from wall width, shelf count, board length, and waste. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolSI Prefixes Reference
Search SI prefix names, symbols, powers of ten, and multipliers from quecto through quetta using a complete local reference in your browser.
Open ToolSimplify Radical Calculator
Free simplify radical calculator that extracts the largest perfect-square factor from a nonnegative integer square root, directly in your browser.
Open ToolSitemap Entry
Build sitemap entry in your browser with a live preview and one-click copy. Free and private: everything is generated locally in your browser with no upload.
Open ToolSlug Batch
Convert multiple titles into lowercase URL slugs with duplicate suffixes. Everything runs locally in your browser with nothing uploaded and no account needed.
Open Toolslug to pound mass Converter
Free slug to pound mass converter with exact factors, reverse conversion, copy-ready output, and a quick reference table that runs in your browser.
Open ToolSlug to Title Case
Free slug to title case converter: turn a URL slug into readable title-case text, computed in your browser.
Open ToolSnell’s Law Calculator
Free Snell’s law calculator: find the refraction angle from refractive indices and the incident angle, in your browser.
Open ToolSocial Post Formatter
Free social post formatter that runs locally in your browser.
Open ToolSocket Address Parser
Free socket address parser that distinguishes hostname, IPv4, bracketed IPv6, raw IPv6, and validated optional ports with strict errors in your browser.
Open ToolSolar Panel Count Estimator
Estimate panel count from monthly kWh target, sun hours, system efficiency, and panel wattage. It runs entirely in your browser, with no uploads or accounts.
Open ToolSort JSON Keys
Free JSON key sorter: alphabetically sort object keys at every level, computed locally in your browser.
Open Toolspan to inch Converter
Free span to inch converter with exact factors, reverse conversion, copy-ready output, and a quick reference table that runs in your browser.
Open ToolSpecific Heat Calculator
Free specific heat calculator: find the heat energy to change a mass by a temperature using Q = mcΔT, in your browser.
Open Toolspeed of light to mile/hour Converter
Free speed of light to mile/hour converter with exact speed math, reverse conversion, copy-ready output, and a quick reference table in your browser.
Open ToolSplit Calculator
Calculate equal split time from total time and number of segments with simple private math. It runs entirely in your browser, with no uploads or accounts.
Open ToolSplit PDF
Split one PDF into several files by page ranges, entirely in your browser, and download each part separately. Your file is never uploaded to a server.
Open ToolSpreadsheet Formula Explainer
Create a plain-language checklist for understanding a spreadsheet formula.
Open Toolsq kilometer to acre Converter
Free sq kilometer to acre converter with exact area math, reverse conversion, copy-ready output, and a quick reference table in your browser.
Open Toolsq yard to sq foot Converter
Free sq yard to sq foot converter with exact factors, reverse conversion, copy-ready output, and a quick reference table that runs in your browser.
Open ToolSQL Create Index
Convert SQL create index in your browser with a live preview and one-click copy. It runs entirely client-side, so nothing is uploaded and no account is needed.
Open ToolSQL IN Clause Generator
Free SQL IN clause generator: turn a list of values into a ready SQL IN clause, computed in your browser.
Open ToolSQL Insert Batch
Convert SQL insert batch in your browser with a live preview and one-click copy. It runs entirely client-side, so nothing is uploaded and no account is needed.
Open ToolSql Insert Statement
Build SQL INSERT statements from column names and pasted row values. A seed file can create insert statements for name, slug, and status columns.
Open ToolSQL Minifier
Free SQL minifier that collapses comments and whitespace into a compact one-line query locally in your browser.
Open ToolSquare Miles to Square Kilometers
Convert square miles to square kilometers and back using the exact international area factor, with six-significant-figure results in your browser.
Open ToolSquare Yards to Square Meters
Convert square yards to square meters and back using the exact international area factor, with six-significant-figure results in your browser.
Open ToolSrcset Sizes
Build srcset sizes in your browser with a live preview and one-click copy. Free and private: everything is generated locally in your browser with no upload.
Open ToolStair Calculator
Free stair calculator: enter the total rise to get the number of steps, the rise per step, and a suggested tread depth, computed in your browser.
Open ToolStandard Deviation Calculator
Free standard deviation calculator with population and sample options, reporting mean, variance, and spread from any list of numbers in your browser.
Open ToolStarter Feeding Calculator
Calculate flour, water, and total weight for a sourdough feeding. Everything is computed locally in your browser, with no uploads and no sign-ups.
Open ToolSteps to Distance Calculator
Free steps to distance calculator: convert a step count into kilometres, miles, and calories from your stride and weight, in your browser.
Open ToolStock Average Down Calculator
Calculate new average share cost after buying more shares at another price. Everything is calculated locally in your browser, with no uploads or sign-ups.
Open ToolStone to Pounds Converter
Convert stone to pounds and pounds to stone with the exact 14-pound definition, reverse conversion, and a practical reference table in your browser.
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