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191+ Free Online Tools for Web, SEO & Developers

Explore 191+ free online tools for web, SEO, and developers. Fast, focused tools—no account required.

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Embed a Website Score

Analyze a public site, then add a live, attributed SiteIndex score widget to your own website.

Check your website score

Company directories

Canadian Company Search

Find Canadian companies by name, corporation ID or Business Number.

Logistics Company Search

Find FMCSA carrier records by company name, USDOT or MC/MX/FF number.

Popular tools

Start with a focused check, then follow related tools for the next step.

Tip Calculator

Work out a tip, optional tax, the final bill, and each person's share when splitting a check. Bill values stay in your browser.

Loan Calculator

Estimate a fixed-rate loan's monthly payment, full month-by-month amortization schedule, and total interest. Your inputs remain in your browser.

Website Score

Measure a public website's SEO, performance, accessibility, security, and technical health.

Internet Speed Test

Measure browser download speed, upload speed, and latency using a lightweight local test.

JSON Formatter

Validate, format, minify, copy, and download JSON with a quick browser-based parser.

Unit Converter

Convert length, weight, temperature, volume, speed, and digital storage units with common cm-to-inch and kg-to-pound pairs preselected.

Random Number Generator

Generate cryptographically random integers from a range, draw unique numbers, roll configurable dice, or flip a coin locally.

Text Counter

Count characters, words, lines, sentences, and estimated reading time for any text block.

Browse all tools

Explore Internet & Network, Website & Domain, Developer, and Utilities tools.

Internet & Network

Check connection speed, DNS records, IP details, latency, and network reachability.

Internet Speed TestMeasure browser download speed, upload speed, and latency using a lightweight local test.What's My IPReveal your public IP and key browser details while keeping the process privacy-friendly.DNS LookupInspect A, AAAA, MX, CNAME, TXT, NS, SOA, and CAA records for a domain.DNS Propagation CheckerCheck whether a DNS change has propagated by comparing a record across 8 public resolvers and the domain's authoritative nameserver.PingMeasure the latency between your browser and a public endpoint using browser-friendly timing.Network Health OverviewReview your public connection quality in one view with IP detection, latency, and speed checks.Port CheckerCheck whether a given host and port appear reachable from the browser environment.
Website & Domain

Inspect website status, HTTP responses, headers, SSL certificates, and domains.

Domain CheckerCheck domain availability, status, and structure in a simple browser-based validator.HTTP Status CheckerCheck the HTTP response for a URL and review the status, server, and redirect chain.Is My Website Down?Test if a site is reachable and quickly review the response status and timing.Website ScoreMeasure a public website's SEO, performance, accessibility, security, and technical health.Website Speed TestTest how fast a website loads: time to first byte, DNS, connection, TLS, download time, page size, compression, and render-blocking resources.Website Health OverviewReview the key status, performance, security, and SEO signals of a public website in one view.Headers CheckerReview HTTP response headers for caching, content type, security, and debugging information.SSL CheckerCheck an SSL certificate's expiry date, issuer, covered hostnames, chain of trust, and TLS version for any domain.Heading ExtractorFetch a public page and list its title, meta description, and H1–H6 heading structure in order.OGP CheckerFetch a public page and review its Open Graph and Twitter/X card tags with a social preview.
Developer

Format, encode, test, hash, convert, and inspect data for development workflows.

Developer Toolkit OverviewReview the most-used developer utilities for JSON, YAML, CSV, regex, timestamps, and build-time helpers in one dashboard.JSON FormatterValidate, format, minify, copy, and download JSON with a quick browser-based parser.Base64Encode and decode UTF-8 text directly in your browser.Hash GeneratorCreate MD5, SHA-1, SHA-256, SHA-384, or SHA-512 checksums locally in your browser, and compare text digests with a published value.Number Base ConverterConvert non-negative integers between binary, decimal, and hexadecimal.JWT DecoderDecode readable JWT headers and payloads locally without verifying signatures.URL EncoderEncode or decode URL strings and query parameter content securely in-browser.UUID GeneratorGenerate version 4 UUID strings using cryptographically secure randomness.Timestamp ConverterConvert between Unix timestamps and human-readable dates in seconds or milliseconds.Regex TesterTest regular expressions against sample text to validate search and parse logic quickly.Cron Job MakerGenerate cron expressions with presets, validation, and human-friendly explanations for common Linux and Unix schedules.YAML to JSONConvert YAML into JSON with validation and instant browser-side output for API and config workflows.JSON to YAMLTransform JSON into YAML for configuration files, deployments, and readable structured data.CSV to JSONParse CSV data into structured JSON arrays and objects for quick app, API, and spreadsheet workflows.JSON to CSVConvert JSON arrays into CSV tables for easy import into spreadsheets and data tools.XML FormatterPretty-print and validate XML with readable indentation, cleanup, and error feedback.SQL FormatterFormat SQL statements with indentation, consistent spacing, and readable database query output.Text DiffCompare two text blocks and highlight the exact additions, removals, and changes between versions.URL ParserBreak down a URL into protocol, host, path, query parameters, hash, and other useful components.HTML Escape / UnescapeEscape HTML special characters into entities or unescape entities back into raw HTML text.ASCII / HEX ConverterConvert text to its hexadecimal byte representation, or decode hex back into readable ASCII text.CSP Header ParserBreak a Content-Security-Policy header into its individual directives and sources for review.CSS Gradient GeneratorBuild linear and radial CSS gradients visually and copy the generated background or text gradient code.Box Shadow GeneratorDesign layered CSS box shadows with a live preview and copy the generated box-shadow declaration.Border Radius GeneratorAdjust each corner radius independently and copy the resulting CSS border-radius declaration.Color Contrast CheckerCheck the contrast ratio between two colors against WCAG AA and AAA accessibility thresholds.OGP Tag GeneratorGenerate Open Graph and Twitter/X meta tags from a title, description, image, and URL.OGP Image SimulatorPreview how a title, description, and image will look as a shared social link card.SVG OptimizerOptimize an SVG in your browser with SVGO, preview its markup, compare file sizes, and download the optimized vector.Subnet CalculatorCalculate an IPv4 subnet's network, broadcast, mask, host range, usable host count, and binary representation locally in your browser.Schema Markup GeneratorGenerate JSON-LD for FAQ, HowTo, Article, LocalBusiness, Product, and Breadcrumb schemas. Structured data stays in your browser.UTM BuilderBuild a campaign URL with source, medium, campaign, term, and content parameters, plus presets and URL validation. Data stays in your browser.SERP PreviewPreview a search result title, description, and URL with desktop and mobile layouts, and measure text pixel widths in your browser.Robots.txt GeneratorBuild a robots.txt file with user-agent, allow, disallow, crawl-delay, and sitemap rules, then download it locally.XML Sitemap GeneratorTurn a pasted list of absolute URLs into XML sitemap entries with optional last-modified dates, change frequency, and priority.TOTP GeneratorGenerate rolling six-digit authenticator codes from a Base32 shared secret using Web Crypto. Secret processing is fully client-side.SSH Key GeneratorGenerate an RSA 2048-bit or ECDSA P-256 SSH key pair in your browser with an OpenSSH public key and PKCS#8 PEM private key.CSR DecoderDecode common subject fields and public-key and signature algorithms from a PEM certificate signing request in your browser.File Hash CheckerCalculate MD5, SHA-1, SHA-256, and SHA-512 digests for local files using browser APIs and a local MD5 implementation. Files are not uploaded.WebSocket TesterConnect to a WebSocket endpoint you choose, send messages, and inspect live events in a browser log. Messages go only to that endpoint.Meta Tag GeneratorCreate escaped page title, description, canonical, robots, viewport, and optional author tags.CSS Button GeneratorStyle a button with live colors, spacing, corners, hover, and keyboard focus, then copy CSS and HTML.XML to JSON ConverterConvert XML to an ordered JSON representation retaining attributes, mixed content, and repeated elements.cURL to Code ConverterConvert a cURL request into Python requests, JavaScript fetch, and PHP cURL examples in your browser.JWT SignerSign JSON claims as a JWT with HMAC or an RS256 private key using browser cryptography.OpenAPI ViewerInspect API operations and paths from an OpenAPI or Swagger document in JSON or YAML..gitignore GeneratorGenerate a starter .gitignore file from common Node, Python, Java, Go, and React presets.CSS Specificity CalculatorEstimate the ID, class, attribute, pseudo-class, and element specificity of a CSS selector.Code Screenshot GeneratorPreview a code snippet and download it as a PNG image rendered in your browser.README GeneratorDraft a project README with a title, description, setup steps, usage section, and SPDX license reference.License Notice GeneratorCreate an SPDX license notice for a project using common license identifiers.
Utilities

Create passwords, QR codes, PDFs, text, colors, dates, and other everyday outputs.

User AgentParse device, browser, and operating system details from the incoming user agent string.Color ConverterConvert colors between HEX, RGB, and HSL in real time.Utility Toolkit OverviewJump into the most popular browser-side utilities for PDFs, QR codes, passwords, image work, and everyday text tasks.QR Code GeneratorGenerate a customizable QR code from text or a URL and download it as PNG or SVG.Merge PDFsCombine multiple PDF files into one document locally in your browser.Split PDFExtract selected pages from a PDF into a new document locally.Remove PDF PagesRemove selected pages from a PDF without uploading the file.Images to PDFCombine PNG and JPEG images into a single PDF document locally.Text to PDFTurn plain text into a simple downloadable PDF document in your browser.Password GeneratorCreate strong random passwords with adjustable length and symbol support.Case ConverterConvert text to upper, lower, title, camel, or snake case in your browser.Lorem Ipsum GeneratorGenerate placeholder paragraphs with adjustable paragraph and word counts.Date DifferenceCalculate the exact difference between two dates and times.Text CounterCount characters, words, lines, sentences, and estimated reading time for any text block.SVG to PNG ConverterUpload or paste SVG markup, preview it, adjust output size, and export a PNG locally in the browser.Image ResizerResize JPG, PNG, and WebP images locally with aspect-ratio locking, presets, and export-quality controls.Markdown PreviewTurn markdown into rendered HTML preview with simple formatting controls for writing and documentation checks.Slug GeneratorCreate clean, URL-friendly slugs from titles and text for blogs, pages, and content management workflows.Line Ending ConverterConvert text between Unix, Windows, and Mac line endings without leaving the browser.UUID ValidatorCheck whether a value is a valid UUID and identify its version and variant.Credit Card ValidatorCheck a card number's Luhn checksum and identify its likely card network from the number pattern.ULID GeneratorGenerate sortable, timestamp-based ULID identifiers as an alternative to random UUIDs.Text Line SorterSort lines of text alphabetically, numerically, by length, or in reverse, with duplicate removal.Duplicate Line RemoverRemove duplicate lines from a block of text while preserving the original order of first occurrences.Text Line JoinerJoin multiple lines of text into a single line using a comma, space, or custom delimiter.Text SplitterSplit text into separate lines using a delimiter such as a comma, space, or custom character.Golden Ratio CalculatorCalculate the complementary dimension of a layout using the golden ratio, approximately 1.618.Aspect Ratio CalculatorCalculate a missing width or height from a known aspect ratio, or find the ratio between two dimensions.PX / REM CalculatorConvert px to rem and rem to px with a configurable base font size, or switch to px to em for sizing relative to a parent font.YouTube Thumbnail DownloaderGet direct links to a YouTube video's thumbnail images in every available resolution.Image CompressorCompress JPG and WebP images in your browser with a quality slider or approximate target size. Files never leave your device.HEIC to JPGConvert HEIC and HEIF photos to JPG in batches without uploading them. Conversion runs locally in your browser.Image Format ConverterConvert image files between JPG, PNG, WebP, AVIF, GIF, BMP, and ICO in your browser. Your files stay on your device.EXIF ViewerInspect EXIF and other image metadata, then create a metadata-stripped copy locally. Your image is never uploaded.Image Palette ExtractorSample an image in your browser to find its most frequent colors, then click a swatch to copy its HEX value.Image CropperCrop, rotate, and flip an image locally with percentage-based bounds. Your image is processed in the browser, never uploaded.Favicon GeneratorCreate 16px and 32px PNG favicons, a 180px Apple touch icon, and an ICO file from an image in your browser.Meme GeneratorAdd top and bottom captions to your own image and download a meme as PNG. Image editing happens entirely in your browser.Image to TextRun browser-based OCR to extract text from an image, then copy or download the transcript. The image is never uploaded.PDF to TextExtract selectable text from a PDF, view the result by page, and copy or download it locally. Your PDF is never uploaded.QR Code ScannerScan a QR code with your camera or decode a QR image in your browser. Camera frames and images are never uploaded.Age CalculatorCalculate age in years, months, and days, discover the weekday you were born, and see a countdown to your next birthday. Dates stay in your browser.Percentage CalculatorFind a percentage of a number, calculate percent change between two values, or work out a discounted price. Calculations stay in your browser.BMI CalculatorEstimate BMI, basal metabolic rate, and daily energy needs using metric or imperial measurements. Health calculations stay in your browser.Loan CalculatorEstimate a fixed-rate loan's monthly payment, full month-by-month amortization schedule, and total interest. Your inputs remain in your browser.Compound Interest CalculatorProject compound growth from an initial deposit, an annual rate, a term, and recurring monthly contributions. Values stay in your browser.Tip CalculatorWork out a tip, optional tax, the final bill, and each person's share when splitting a check. Bill values stay in your browser.GST/HST CalculatorEstimate combined Canadian sales tax by province or territory, add tax to a price, or remove tax from a tax-included total. Amounts stay local.Salary to Hourly CalculatorConvert annual, monthly, biweekly, semimonthly, or weekly pay into an hourly estimate, with weekly hours and overtime inputs. Pay values stay local.Unit ConverterConvert length, weight, temperature, volume, speed, and digital storage units with common cm-to-inch and kg-to-pound pairs preselected.Currency ConverterConvert between more than 150 currencies using the open.er-api.com exchange-rate feed. Only the requested currency code is sent for rates.Sleep CalculatorEstimate bedtime options for a target wake-up or wake-up times for a chosen bedtime using 90-minute cycles and time to fall asleep.Countdown TimerCreate a titled event countdown with days, hours, minutes, and seconds. Share one exact deadline across timezones through a link or social platform.Online StopwatchRun a browser stopwatch with pause, reset, lap times, and fullscreen mode. Timing remains on your device.Pomodoro TimerUse customizable focus, short-break, and long-break intervals with a task label, optional sound, completed-session count, and a downloadable summary.Fraction CalculatorAdd, subtract, multiply, or divide fractions, simplify the result, and see its decimal equivalent in your browser.Scientific CalculatorEvaluate typed arithmetic expressions with parentheses, powers, pi, e, and trigonometric and logarithmic functions. Calculations stay local.Statistics CalculatorPaste a list of numbers to calculate mean, median, mode, population standard deviation, and range locally in your browser.Business Days CalculatorCount weekdays between two dates, excluding weekends and an optional custom list of holiday dates. Date ranges stay in your browser.Microphone TestCheck microphone input level, choose an available device, and record a sample for playback. Audio stays in your browser and is never uploaded.Webcam TestPreview your webcam, check its reported video resolution, and save a snapshot as PNG. Camera frames stay in your browser and are never uploaded.Speaker TestPlay separate left- and right-channel tones or a frequency sweep to check speaker output. Audio is generated locally in your browser.Keyboard TesterCheck held and detected keys on a visual keyboard, including navigation and numpad keys. Key codes remain in memory until reset or leaving the page.Typing TestTake a 60-second typing test with rotating sample texts and see words per minute and character accuracy. Typed text remains in your browser.Reaction Time TestMeasure visual reaction time across five attempts and compare your average and best response. Timing is local to your browser.Screen TestCycle fullscreen solid colors to inspect a display for stuck or dead pixels. The test uses local browser rendering and sends no screen data.Text EncryptorEncrypt and decrypt text locally with AES-256-GCM and a passphrase-derived key. Plaintext and passphrases are never uploaded.Wi-Fi QR Code GeneratorCreate a scannable QR code from an SSID, network security type, password, and hidden-network setting. Credentials stay in your browser.Barcode GeneratorGenerate Code 128, EAN-13, UPC-A, or Code 39 barcodes from text or digits, then download PNG or SVG locally.Text to SpeechRead text aloud with browser speech voices, adjustable rate and pitch, and optional voice selection. Text is passed to your browser's speech engine, not SiteIndex.Speech to TextDictate a live transcript with the browser Web Speech API, then copy or download the recognized text. Speech processing depends on browser support.Voice RecorderRecord microphone audio in your browser with a live input-level meter, then play or download the local recording.Fancy Text GeneratorConvert plain Latin letters into decorative Unicode styles and copy each variant. Text conversion happens locally in your browser.ASCII Art GeneratorRender a short phrase as monospaced FIGlet ASCII art using several font styles, then copy the text from your browser.Morse Code TranslatorTranslate letters and digits to International Morse code or decode Morse back to text, with optional browser-generated tone playback.Spin WheelSpin a wheel to choose a random name or option from an editable list. Your entries are saved in this browser's local storage.Random Number GeneratorGenerate cryptographically random integers from a range, draw unique numbers, roll configurable dice, or flip a coin locally.Invoice GeneratorCreate a simple invoice with line items, tax, and an optional local logo, then print or save it as PDF through your browser.Citation GeneratorDraft starter APA, MLA, or Chicago citations for a book or web source from author, title, year, publisher, and URL fields.GPA CalculatorCalculate a credit-weighted GPA from course grades and credits, or estimate the GPA needed in upcoming courses to reach a target.Email ExtractorExtract and deduplicate email addresses, phone-like numbers, and URLs from pasted text, then export the matches as CSV locally.Readability CheckerEstimate English Flesch Reading Ease, Flesch-Kincaid grade level, word and sentence counts, and reading time locally.Chart MakerTurn pasted CSV data into a bar, line, or pie chart and download the canvas as PNG without uploading the dataset.White NoisePlay locally generated white, pink, or brown noise through the Web Audio API with a volume control and optional sleep timer.MetronomeSet a 20–300 BPM tempo and time signature, tap to estimate a beat, and hear browser-generated metronome clicks.Love CalculatorGenerate a playful, repeatable name-pair compatibility score for entertainment. The toy calculation runs locally and is not relationship advice.Magic 8 BallAsk a yes-or-no question and get a random classic-style 8-ball response, with optional device shake interaction. It is a toy, not advice.Mortgage CalculatorEstimate monthly mortgage principal, interest, property tax, and insurance with a fixed-rate calculation.EMI CalculatorCalculate a fixed equated monthly instalment, total interest, and total loan repayment.Sales Tax CalculatorAdd sales tax to a price or reverse an inclusive total to find the price before tax.Retirement CalculatorProject retirement savings from contributions, assumed returns, and inflation, with a today-value comparison.ROI CalculatorCalculate investment gain or loss, total return on investment, and annualized return.Pregnancy Due Date CalculatorEstimate a pregnancy due date from the first day of your last period and usual cycle length.Ovulation CalculatorExplore an estimated ovulation date and fertile window using a regular-cycle calendar assumption.Ideal Weight CalculatorSee the adult weight interval corresponding to BMI 18.5-24.9, without prescribing one ideal weight.Macro CalculatorIllustrate adult maintenance energy and a stated protein, carbohydrate, and fat split.Water Intake CalculatorExplore a rough weight-based adult daily fluid range with explicit health and hydration limitations.BAC CalculatorExplore an educational blood alcohol estimate and why a calculation cannot establish driving safety.Volume ConverterConvert litres, millilitres, cubic units, and explicitly labeled US and Imperial volumes.Length ConverterConvert metric lengths and international inches, feet, yards, and miles with instant results.Temperature ConverterConvert Celsius, Fahrenheit, and Kelvin with offset-aware formulas and absolute-zero validation.Weight ConverterConvert milligrams, grams, kilograms, ounces, pounds, and stones using standard mass definitions.Density CalculatorCalculate density from a measured mass and volume, with explicit units and SI results.Roman Numerals ConverterConvert whole numbers from 1 to 3999 into Roman numerals, or validate and decode Roman notation.Alarm ClockSet a local browser alarm with a visual alert and optional sound while the page remains open.CalendarView any Gregorian month from 1900 to 2199 with localized labels and Sunday-first weeks.Time CalculatorAdd or subtract signed durations with hours, minutes, seconds, and optional milliseconds.World ClockCompare live times and local dates across selected IANA time zones using your device clock.Grade CalculatorCalculate a weighted average from percentage scores and matching weights, with normalization shown.Concrete CalculatorEstimate rectangular slab volume, waste allowance, and whole bags from a manufacturer-specified yield.Roofing CalculatorEstimate simple pitched-roof surface area and roofing squares from a horizontal footprint and pitch.Square Footage CalculatorCalculate rectangle, triangle, or circle area in square feet and square metres with explicit dimensions.Slope CalculatorCalculate rise, run, line inclination, and distance between two points, including vertical-line handling.Standard Deviation CalculatorCompare population and sample standard deviation with variance, mean, and count for a numeric list.Significant Figures CalculatorCount significant figures using stated zero conventions and round decimal digits into explicit scientific notation.Long Division CalculatorDivide signed whole numbers exactly with quotient, remainder, and digit-by-digit absolute-value steps.Number to Words ConverterSpell signed decimals in English short-scale words while preserving individually spoken fractional digits.Force CalculatorCalculate one-dimensional Newtonian net force from mass and signed acceleration in SI units.Kinetic Energy CalculatorCalculate classical translational kinetic energy from mass in kilograms and velocity in metres per second.Velocity CalculatorCalculate average one-dimensional velocity from signed displacement and positive elapsed time.Running Pace CalculatorCalculate average elapsed pace per kilometre and mile plus speed from distance and duration.Dice RollerRoll up to 100 custom-sided dice using browser cryptographic randomness with individual results and a total.Bra Size CalculatorExplore an approximate adult US/UK bra-fitting starting size from underbust and bust measurements.

Practical website troubleshooting workflows

A single check rarely explains a website problem. Start with the symptom, compare related signals, and treat each result as a point-in-time observation rather than a guarantee.

A site is slow or unreachable

  1. Check the public response with Website Down Checker; one successful check cannot prove availability for every visitor.
  2. Use Website Speed Test to inspect response timing, then compare from the same device and network.
  3. Check the certificate with SSL Checker if browsers report a security warning.