W3HTech - Free Online Tools, Calculators & Tech Blog

Developer Tools

HTML Email Template Generator

Easy-to-use tool to generate HTML email templates.

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JSON Formatter

Format, validate, and beautify JSON data instantly.

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YAML Formatter

Format, validate, and beautify YAML data instantly.

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Regex Helper

Build, test, and learn regular expressions with live match highlighting and a plain-English explainer.

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curl Command Builder

Build, preview, and copy curl commands from a simple request form.

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Markdown Viewer

Write and preview Markdown with live lint feedback, right in your browser.

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HAR Analyzer

Inspect HAR files — requests, timing, and security issues — entirely in your browser.

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Unicode Converter

Convert text between any language and Unicode escape sequences for i18n/localization.

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Emoji Generator

Search, choose, and copy emojis — or build a custom combo to paste anywhere.

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Encoder / Decoder

Encode and decode text using Base64, URL encoding, and Hex — instantly, right in your browser.

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Epoch Converter

Convert Unix epoch timestamps to human-readable dates and back, with UTC/local timezone support and a live current-timestamp clock.

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Icon Generator

Upload an image and generate a full set of favicon and app icon sizes, ready to download and drop into your site.

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UUID Generator

Generate UUIDs (v1, v4, v7, or Nil) in bulk, with case, hyphen, and brace formatting options — entirely in your browser.

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JWT Decoder

Decode JSON Web Tokens (JWT) — inspect header, payload, and signature — instantly, right in your browser.

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Word Counter

Count words, characters, sentences, and paragraphs, estimate reading time, and generate lorem ipsum text.

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QR Code Generator

Turn any text or link into a downloadable QR code, right in your browser.

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CSV ↔ JSON Converter

Convert between CSV and JSON, with nested object/array flattening to dot-notation columns.

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Password Generator

Generate strong, random passwords with a strength meter, entirely in your browser.

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Hash Generator

Generate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes for text or files, entirely in your browser.

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Diff Checker

Compare two blocks of text or code with a unified or side-by-side diff view, entirely in your browser.

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Lorem Ipsum Generator

Generate placeholder words, sentences, or paragraphs of classic Lorem Ipsum text.

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HTTP Status Codes

Search and browse every HTTP status code with its meaning and common causes.

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Fake Data Generator

Generate realistic dummy JSON and CSV records for testing — names, emails, addresses, and more.

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kubectl Command Builder

Build common kubectl commands — get, describe, logs, exec, scale, and more — with the right flags, ready to copy.

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SQL Formatter

Format and beautify SQL queries in your browser, with dialect options for Standard SQL, MySQL, PostgreSQL, and more.

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Cron Expression Builder

Build or paste a cron expression and get a plain-English description plus the next run times.

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JSON to TypeScript

Paste JSON and generate TypeScript interfaces or type aliases, with nested types and optional fields.

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Text Case Converter

Convert text between camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, Title Case, and more, instantly.

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Markdown Table Generator

Build or paste a Markdown table, edit it in a spreadsheet-like grid with column alignment, and copy the result.

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Random Number Generator

Generate random numbers in a range, unique picks, decimals, or roll dice.

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Sumo Logic Query Builder

Build Sumo Logic search queries visually — scope filters, keyword terms, and chained pipe operators.

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SQL Query Builder

Build SQL SELECT queries visually with a live join visualizer that runs joins against sample data.

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URL Query Parser / Builder

Break a URL into its protocol, host, path, and query parameters, edit them in a table, and get the rebuilt URL live.

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Gantt Chart Generator

Plan projects with a drag-to-schedule Gantt chart that runs entirely in your browser.

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Responsive Design Checker

Preview any URL at mobile, tablet, laptop, and desktop widths side by side, plus a custom-width mode.

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Developer Learning

React Tutorial

Learn React fundamentals with live, editable code examples in an interactive lesson-by-lesson playground.

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Python Tutorial

Learn Python fundamentals with real, runnable code examples in an in-browser lesson-by-lesson playground.

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ML Concepts

Learn machine learning concepts interactively — visual demos, quizzes, and a glossary for developers new to ML.

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Kubernetes Learning Lab

Learn Kubernetes interactively with a cheat sheet, quizzes, a kubectl simulator, and hands-on YAML challenges.

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Backend Engineering

Learn backend engineering from HTTP and REST APIs to the distributed-systems principles behind databases, with hands-on simulators and quizzes.

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System Design 101

Learn software system architecture and how to design scalable systems, through guided topics, diagrams, quizzes, and worked case studies.

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Linux Learning Lab

Learn Linux interactively with a cheat sheet, quizzes, a terminal simulator, and hands-on shell challenges.

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Cybersecurity Learning Lab

Learn cybersecurity basics through interactive lessons, hands-on simulations, quizzes, and a searchable glossary.

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Kafka Learning Lab

Learn Apache Kafka interactively with a cheat sheet, topic quizzes, a simulated Kafka CLI, a script playground, and hands-on broker challenges.

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Docker Learning Lab

Learn Docker interactively with guided lessons and a searchable cheat sheet covering images, containers, Dockerfiles, volumes, networking, and Compose.

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Observability Learning Lab

Learn observability, monitoring, and logging hands-on with a cheat sheet, topic quizzes, a simulated metrics/logs/traces dashboard, and guided incident-diagnosis challenges.

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Git Learning Lab

Learn Git interactively with a simulated terminal, live commit-graph visualization, guided challenges, quizzes, and a cheatsheet.

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Calculators

Math Problem Generator

Generate addition, subtraction, linear equation, and quadratic equation problems with solutions.

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Energy Usage Calculator

Estimate annual energy use and cost to operate household appliances.

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Age Calculator

Calculate your exact age in years, months, and days from your date of birth.

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EMI Calculator

Work out your monthly loan EMI, total interest, and total payment from the amount, rate, and tenure.

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Unit Converter

Convert between length, weight, volume, and temperature units, instantly in your browser.

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BMI Calculator

Calculate your Body Mass Index and category from weight and height, in metric or imperial units.

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Scientific Calculator

Arithmetic, trig, log, and factorial with memory and calculation history.

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Currency Converter

Convert between world currencies using live exchange rates, with a full rate comparison table.

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Tip Calculator

Work out the tip and total from a bill amount, tip percentage, and split it between any number of people.

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Budget Planner

Track income, expenses, budgets, recurring bills, and savings goals to manage your personal life budget — all stored locally in your browser.

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Network & Internet

What Is My IP

Find your public IP address, location, and ISP instantly.

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Internet Speed Tester

Test your download, upload, latency, jitter, and packet loss speed instantly.

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Ping Test

Measure round-trip latency to any host with a live trace, right in your browser.

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DNS Lookup

Query A, AAAA, MX, TXT, NS, SOA, CAA, and PTR records against Cloudflare or Google's public resolvers, side by side.

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Timezone Converter

Compare times across multiple cities side by side, search by city name, and share a link to your exact setup.

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WHOIS Lookup

See who a domain is registered to, when it expires, and which name servers it uses.

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Subnet Calculator

Calculate network address, broadcast, host range, and usable hosts from IPv4 CIDR notation.

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User-Agent Parser

Auto-detect your browser's User-Agent, or paste any string, and decode its browser, engine, OS, and device type.

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Network Explorer

Interactive IPv4 networking toolkit — subnet and port calculators, animated protocol visualizers, and a networking quiz, all client-side.

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Design & Drawing

Whiteboard

A free online whiteboard for brainstorming and explaining ideas — draw, write, and sketch with shapes, sticky notes, and text. Auto-saves in your browser.

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Color Palette Generator

Generate harmonious color palettes with hex/RGB/HSL values, lock colors you like, and reroll the rest.

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Gradient Generator

Build linear and radial CSS gradients with a live preview, adjustable color stops and angle, and one-click copy.

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Color Contrast Checker

Check WCAG AA/AAA contrast ratios between text and background colors, with live pass/fail badges.

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Box Shadow Generator

Stack multi-layer CSS box-shadows with live preview, per-layer offset/blur/spread/color controls, and one-click copy.

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CSS Border Radius Generator

Set a horizontal and vertical radius for each corner and get the matching CSS, including the elliptical-corner syntax.

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Flexbox/Grid Playground

Adjust flexbox and grid container properties with a live preview and copy the generated CSS.

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ASCII Art Generator

Turn text into block-letter ASCII art banners with a custom fill character, ready to copy.

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Image Editor

Adjust, rotate, flip, and crop a photo right in your browser — nothing is uploaded.

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Font Creator

Draw your own handwriting font letter by letter and export it as a real, installable OTF/WOFF2 font file.

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UML Diagram Designer

Create UML class, sequence, use case, and flowchart diagrams with a drag-and-drop visual editor, then export as PNG/SVG, save as JSON, or share via a link.

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Paint Color Picker

Upload a photo of a wall, click a spot on it, and instantly see its hex/RGB/HSL plus the nearest common paint-like color name.

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Media & Entertainment

Web Music Player

A retro-styled player for your own local audio files, with a playlist and live spectrum visualizer.

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Internet Radio Player

Curated live internet radio stations across genres, with favorites and volume control.

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Metronome

Adjustable-tempo metronome with tap tempo, time signatures, and selectable click sounds.

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News Feed Reader

Subscribe to RSS/Atom feeds and read headlines and summaries from your favorite sites, right in your browser.

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Audio Editor

Trim, cut, fade, normalize, and merge audio clips right in your browser — no upload, no install, fully client-side.

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Video Editor

Trim, arrange, and export multi-track video projects entirely in your browser.

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Travel & Outdoors

Trail Finder

Find hiking trails, peaks, and viewpoints near you or any location you search for.

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Kids & Learning

BrixQuest

Pick a theme, age, and difficulty for a step-by-step LEGO build with a parts list and assembly pictures.

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BotForge

Pick a platform and category for a LEGO MINDSTORMS build with wiring diagram, parts list, and a block-based program.

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Typing Tutor

Practice your typing speed and accuracy with adjustable difficulty, live stats, and mistake tracking.

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Times Tables Trainer

Practice multiplication tables with a timed quiz, adjustable range, and instant feedback.

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Memory Match Game

Flip cards to find matching pairs, with adjustable difficulty, a move counter, and a timer.

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Word Search Generator

Enter a word list and generate a puzzle grid, then drag across letters to find each word.

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Cat Name Generator

Pick a theme and coat color, then generate a shortlist of cat name ideas to swap and copy.

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Country Flags Quiz

Match flags to their countries in a multiple-choice quiz, filterable by region.

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Solar System Explorer

Explore facts about every planet and test your knowledge with a quiz.

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Word of the Day

Learn a new vocabulary word daily and build your streak.

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Quote of the Day

A fresh inspirational quote daily, browsable by category, with favorites.

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Road Sign Quiz

Learn US road signs with a browsable reference and a multiple-choice quiz.

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Recyclables Guide

Look up whether common materials are recyclable, plus a sorting quiz.

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Morse Code Translator

Translate text to and from Morse code, play it as audio beeps, and practice with an interactive trainer.

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Periodic Table Explorer

Explore the periodic table of elements — search, filter by category, and view detailed properties for every element.

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Electricity Basics

Learn voltage, current, resistance, and watts with an Ohm's Law calculator, a maker-friendly glossary, an interactive circuit visualizer, and a quiz.

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Electronic Components

Learn resistors, capacitors, transistors, and diodes — decode color/EIA codes, browse a component glossary, and test your knowledge.

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Piano Basics

Learn piano note names and keyboard layout with an interactive on-screen keyboard — free play, note-finding, and key-naming exercises.

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Guitar Basics

Learn guitar with interactive fretboard visualization, chord diagrams, step-by-step lessons, song practice, and real-time tuning via microphone.

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Hot Wheels Garage

Browse a colorful collection of Hot Wheels toy cars, save your favorites to My Garage, and spin the wheel for a surprise pick.

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Flute Basics

Learn flute from scratch with an interactive fingering chart, step-by-step lessons, a metronome, and microphone-based note practice.

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English Buddy

Learn English grammar with interactive quizzes, a browsable grammar reference, vocabulary flashcards, and a rule-based sentence checker.

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Astrology & Panchangam

Moon Phase Calculator

Choose a month and year to view the moon phases for each day.

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Sun Rise Sun Set Calculator

Choose a month and year to view sunrise and sunset times for each day.

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Rahu Kaalam Calculator

Choose a month and year to view Rahu Kaalam — a period each day considered inauspicious.

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Tithi Calculator

Choose a month and year to view the Tithi and Paksha for each day — key inputs for selecting a muhurta.

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Nakshatra Calculator

Choose a month and year to view the nakshatra — the lunar zodiac of Vedic astrology — for each day.

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Zodiac Compatibility Calculator

Enter two birth dates to see their zodiac signs and a compatibility breakdown across love, friendship, and work.

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Numerology Calculator

Enter your full birth name and birth date to reveal your Life Path, Destiny, and Soul Urge numbers.

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Digital Compass

Uses your device's orientation sensor to show a live heading with a rotating compass rose.

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Vedic Horoscope

Your real sidereal Moon rasi from the Swiss Ephemeris, plus a daily reading grounded in today's actual planetary transits.

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Tamil Panchangam

Today's Tamil date and full Panchangam — thithi, nakshatra, yogam, karanam, and Rahu Kaalam — computed from precise astronomical calculations.

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Tamil Calendar

A monthly Tamil calendar grid with Tamil date, tithi, nakshatra, and festivals for every day, plus a downloadable yearly .ics export.

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Tamil Jathagam

Full Vedic birth chart (jathagam): Lagna, Rasi and Navamsa charts, planetary positions, Vimshottari Dasha, and marriage-matching attributes, computed with the Lahiri ayanamsa.

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Blog

Read the latest technology and computer programming articles.

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