Guides, how-tos & explainers
Practical, no-fluff articles on the tools developers reach for every day — how to use them well, and the mistakes worth avoiding.
Are UUIDs Really Unique?
In practice UUIDs never collide - here is the math behind why, and the one thing people get wrong: a UUID is an identifier, not a secret.
Read articleBulk Find & Replace with Regex
How to use regular expressions for bulk find and replace - matching patterns, capturing groups, and swapping many variants in a single pass.
Read articlecamelCase vs snake_case vs kebab-case Explained
A clear breakdown of camelCase, snake_case and kebab-case - what each looks like, where each belongs in code, and how to convert between them.
Read articleHow to Combine Images into One PDF
How to merge several photos or scans into a single, correctly ordered PDF - without uploading your files anywhere.
Read articleConventional Commits Explained
What Conventional Commits are, the full list of types, and why teams adopt the spec to automate versioning and changelogs.
Read articleHow to Convert PDF to Word and Keep Formatting
Learn what formatting survives a PDF-to-Word conversion, how to protect fonts and tables, and when a scanned document needs OCR first.
Read articleDescribe It, Don't Write It: AI Regex
Why generating a regular expression from what you mean beats writing it symbol by symbol — and how to verify the result.
Read articleencodeURI vs encodeURIComponent Explained
The clear difference between encodeURI and encodeURIComponent, with examples showing which one to use for a value versus a whole URL.
Read articleFavicon Sizes & Formats Explained
A clear guide to the favicon sizes and formats modern sites need - ICO, PNG, and SVG - and the exact link tags to wire them up.
Read articleHow to Convert a File to a Base64 Data URI
Turn an image or font into a self-contained data: URI you can paste straight into CSS or HTML - and know when the size trade-off is worth it.
Read articleHEX vs RGB vs HSL Color Codes Explained
HEX, RGB and HSL describe the same colors three different ways - here is what each one means and when to reach for it in CSS and design.
Read articleHow AI Code Explainers Work
A high-level look at how large language models read and explain code, and where their limits are.
Read articleHow EMI Works: Principal, Interest & Tenure
A plain-English explanation of how each EMI splits into principal and interest across the loan tenure.
Read articleHow Many Days Until a Date? A Simple Guide
How to count the days until a future date accurately, including the inclusive-versus-exclusive trap that makes two people get different answers.
Read articleHow to Add a Watermark to a PDF
A step-by-step guide to stamping a text or image watermark - Draft, Confidential, or a logo - across a PDF, free and entirely in your browser.
Read articleHow to Calculate a Percentage
Master the one percentage formula behind percent-of and what-percent questions, with worked examples you can check against an online calculator.
Read articleHow to Calculate a Tip
Learn the one tip formula plus quick mental-math shortcuts for 10%, 15%, 18% and 20%, with worked examples you can verify instantly.
Read articleHow to Calculate Age Between Two Dates
How to measure the exact interval between any two dates in years, months and days - the logic, the traps, and the quick way.
Read articleHow to Calculate Days Between Two Dates
A practical walkthrough for counting the exact days, weeks and months between two dates without off-by-one errors or leap-year surprises.
Read articleHow to Calculate Loan EMI
A step-by-step guide to calculating your loan EMI using the standard formula, with a worked example you can follow.
Read articleHow to Calculate Percentage Increase & Decrease
Use one percentage change formula to handle increases, decreases, discounts and growth rates - with worked examples and the traps that catch people out.
Read articleHow to Calculate Your BMI
Work out your body mass index by hand in metric or imperial units, with the exact formula, a worked example and the pitfalls to avoid.
Read articleHow to Calculate Your Exact Age
A step-by-step guide to getting your exact age in years, months and days from a birth date - by hand and the easy way.
Read articleHow to Change Text Case Online
A quick, practical guide to converting text between UPPERCASE, lowercase, Title Case and Sentence case online without retyping a thing.
Read articleHow to Combine Multiple PDFs into One File
How to bundle many PDFs - reports, scans and invoices - into one well-ordered file, with practical tips for getting large batches right.
Read articleHow to Compare Two Texts Online
Learn how to compare two blocks of text online and read exactly what was added, removed or changed - line by line, without missing a thing.
Read articleHow to Compress a PDF Online
A simple step-by-step guide to shrinking a PDF in your browser so it fits email and upload size limits - free, fast, and private.
Read articleHow to Compress an Image Online
A simple step-by-step guide to shrinking an image in your browser so it fits email and web upload limits - free, fast, and private.
Read articleHow to Convert an Image (PNG, JPG, WebP)
A step-by-step guide to converting images between PNG, JPG, and WebP online, right in your browser.
Read articleHow to Convert an Image to Base64
Turn a PNG, JPG or SVG into a Base64 data URI you can paste straight into HTML or CSS - encoded locally in your browser.
Read articleHow to Convert Between Time Zones
A step-by-step guide to converting a time from one zone to another accurately, including the daylight saving and date-rollover traps that catch people out.
Read articleHow to Convert JPG to PDF
A step-by-step guide to turning JPG and PNG images into a clean, correctly sized PDF - without uploading anything.
Read articleHow to Convert PDF to JPG
A step-by-step guide to exporting every page of a PDF as a JPG image online, right in your browser.
Read articleHow to Convert PDF to Word
Turn a locked PDF into an editable Word document in a few clicks, entirely in your browser - no upload, no sign-up, no watermark.
Read articleHow to Convert PNG to WebP
A step-by-step guide to converting PNG images to WebP for smaller, faster web pages, right in your browser.
Read articleHow to Convert Units Online
A practical walkthrough for converting length, weight and temperature units online, correctly and without guessing the formula.
Read articleHow to Convert a Unix Timestamp to a Date
A practical walkthrough for turning a raw Unix timestamp into a readable local, UTC or ISO date - and converting a date back into a timestamp.
Read articleHow to Count Words & Characters Online
Learn how to count words, characters, sentences and paragraphs online in a few clicks - live, private and entirely in your browser.
Read articleHow to Create a Favicon for Your Website
A step-by-step guide to turning an image into a favicon and wiring it into your website, right in your browser.
Read articleHow to Create SEO-Friendly URL Slugs
A step-by-step walkthrough that turns any page title into a clean, lowercase, hyphenated URL slug search engines and readers both like.
Read articleHow to Crop an Image Online
A step-by-step guide to cropping an image to a selection online, right in your browser.
Read articleHow to Crop an Image to a Specific Aspect Ratio
A step-by-step guide to cropping an image to a fixed aspect ratio like 1:1 or 16:9 for social and profile photos.
Read articleHow to Decode a JWT Token
Decode any JSON Web Token to read its header and payload claims in seconds — safely, right in your browser.
Read articleHow to Deduplicate a List Online
A quick, practical guide to deduplicating a list online - removing repeated entries cleanly while handling case, whitespace, and merged lists.
Read articleHow to Delete Pages from a PDF
A step-by-step guide to removing single pages or ranges from a PDF and saving a smaller file, all in your browser.
Read articleHow to Diff Two JSON Files Online
Learn how to compare two JSON files online and read exactly what was added, removed or changed — by path, without the noise of a text diff.
Read articleHow to Encode & Decode Base64 Online
A quick, correct walkthrough for encoding and decoding Base64 text online - including the UTF-8 and emoji edge cases that trip people up.
Read articleHow to Encode & Decode URLs Online
Encode or decode a URL or query value in seconds, choosing the right scope — component versus full URL — every time.
Read articleHow to Extract Pages from a PDF
A practical, step-by-step guide to pulling specific pages out of a PDF into a new file - free, private and entirely in your browser.
Read articleHow to Find and Replace Text Online
A practical walkthrough for finding and replacing text online, including the case and whole-word options that decide exactly what gets swapped.
Read articleHow to Fix a Sideways or Upside-Down PDF
Why a scan opens sideways or upside-down, and how to correct its orientation permanently so the file reads upright for everyone.
Read articleHow to Generate a JSON Schema
Learn how to turn a sample JSON document into a JSON Schema, then refine the inferred types and required fields into a contract you can validate against.
Read articleHow to Generate a UUID Online
Generate random v4 or time-ordered v7 UUIDs online, one at a time or in bulk, with the exact case, hyphen and brace formatting your system expects.
Read articleHow to Generate an MD5 or SHA-256 Hash Online
A quick, practical walkthrough for turning any text or file into an MD5 or SHA-256 digest right in your browser.
Read articleHow to Generate Placeholder Text
A practical, step-by-step guide to producing realistic dummy text for mockups - by paragraph, sentence or word - without installing a thing.
Read articleHow to Generate Regex from Plain English
Describe the pattern you need in plain English, generate a working regex, and verify it against real samples — step by step.
Read articleHow to Generate SQL from Plain English
A step-by-step guide to turning a plain-English question into a working SQL query with AI, using your schema for accuracy.
Read articleHow to Merge PDF Files Online
A clear, step-by-step walkthrough for combining several PDFs into one file online - and getting the page order right before you merge.
Read articleHow to Pick a Color from an Image
Use an eyedropper to sample the exact pixel color you want and copy it as HEX, RGB or HSL - accurately, and without guessing by eye.
Read articleHow to Preview HTML Online (Without Installing Anything)
See any HTML snippet rendered as a real page in seconds — straight in your browser, nothing to install.
Read articleHow to Preview Markdown Online
See your Markdown rendered live as you type - headings, lists, tables and code - right in your browser, with nothing to install.
Read articleHow to Remove Duplicate Lines from Text
A practical walkthrough for removing duplicate lines from text online, including the case-sensitivity and whitespace details that decide what counts as a duplicate.
Read articleHow to Remove EXIF Metadata from Photos
Learn exactly what EXIF metadata hides in your photos - location, camera, timestamps - and how to strip it all out in a few clicks, entirely in your browser.
Read articleHow to Remove Unwanted Pages from a PDF
How to spot and remove blank, duplicate and unwanted pages from a PDF so you share a clean, professional file every time.
Read articleHow to Resize an Image Online
A simple step-by-step guide to resizing an image in your browser by pixels or percentage - free, fast, and with nothing uploaded.
Read articleHow to Resize an Image Without Losing Quality
How to keep your images sharp when you resize them - the difference between downscaling and upscaling, keeping aspect ratio, and avoiding blur.
Read articleHow to Rotate PDF Pages Online
A step-by-step guide to rotating some or all pages of a PDF in 90-degree steps and saving the fix so it sticks, all in your browser.
Read articleHow to Schedule Meetings Across Time Zones
How to find overlapping working hours across time zones and pick a meeting slot that is fair to everyone - without the daylight saving and date-rollover slip-ups.
Read articleHow to Split a Bill with Tip
Split any restaurant bill plus tip evenly among your group with one clear formula, worked examples, and rounding tips that actually add up.
Read articleHow to Split a PDF into Multiple Files
A clear, step-by-step walkthrough for splitting one PDF into several separate files by page range - free, private and entirely in your browser.
Read articleHow to Spot Differences Between Two Documents
Learn how to find every edit between two versions of a document - added, removed and changed lines - without re-reading the whole thing.
Read articleHow to Summarize Long Text with AI
A practical guide to condensing long articles, reports and documents into clear key points with AI - without losing the meaning.
Read articleHow to Test HTML Email Templates Online
Preview an HTML email template online and check the details that actually break in real inboxes — inline styles, table layouts, and thin CSS support.
Read articleHow to Test a Regex Online
A practical, step-by-step guide to writing and testing a regular expression online with live match highlighting.
Read articleHow to Understand Unfamiliar Code with AI
A practical, step-by-step guide to using an AI code explainer to understand a snippet you did not write.
Read articleHow to Verify a File Checksum
A published checksum only helps if you actually check it - here is how to hash a download and compare it correctly.
Read articleHow to Watermark a PDF for Free
How to watermark a PDF for free in your browser, with practical tips on positioning and opacity so the mark reads clearly without hiding your content.
Read articleHow to Write a TL;DR Automatically
How to generate a clear, honest TL;DR automatically - what makes a good one, where it belongs, and the mistakes that make it useless.
Read articleHow to Write Better Git Commit Messages
A practical guide to writing Git commit messages your future self will thank you for — the right structure, tense, and level of detail.
Read articleHTML Preview vs a Local Server: Which for Quick Tests?
Compare an online HTML preview with a local dev server so you know which one to reach for on any given test.
Read articleJPG vs PNG vs WebP: Which Image Format to Use
A clear comparison of JPG, PNG, and WebP - which to use for photos, graphics, and transparency, and when WebP beats them both.
Read articleJSON Beautify vs Minify: When to Use Each
Beautify JSON when a human needs to read it; minify it when a machine needs to move or store it — and know that both transforms are perfectly lossless.
Read articleJWT Decode vs Verify: What's the Difference?
Decoding reads a token's claims; verifying proves they're genuine — mixing them up is how JWT security goes wrong.
Read articleMarkdown Cheat Sheet: Syntax Basics
The Markdown syntax you'll actually use every day - headings, lists, links, code and tables - in one quick reference.
Read articleMD5 vs SHA-256: Which Should You Use?
MD5 is fast but broken; SHA-256 is the safe default - here is when each one is the right tool.
Read articleHow to Merge PDFs Without Losing Quality
Why merging PDFs is lossless when done correctly, and how to avoid the re-compression traps that quietly degrade text and images.
Read articleMetric vs Imperial: A Quick Conversion Guide
The handful of metric-imperial conversions worth knowing by heart, and simple tricks for remembering them.
Read articleNatural Language to SQL: A Practical Guide
How natural-language-to-SQL actually works, why schema context is the key input, and how to review the output before you trust it.
Read articleHow to Reduce Image File Size Without Losing Quality
How to shrink an image while keeping it looking sharp - understand lossy vs lossless, pick the right quality level, and choose the best format.
Read articleHow to Reduce PDF File Size Without Losing Quality
Understand what actually makes PDFs large and how to balance compression against quality so your files stay small and readable.
Read articleCapture Groups & Named Groups in Regex
How numbered capture groups, named groups, and non-capturing groups work — and how to read the values they produce.
Read articleRegex Flags Explained (g, i, m, s, u, y)
What each JavaScript regex flag does — g, i, m, s, u, y — with a short example of what changes when you toggle it.
Read articleSeconds vs Milliseconds Timestamps Explained
The difference between a 10-digit seconds timestamp and a 13-digit milliseconds one is a factor of 1000 - and getting it wrong sends your dates thousands of years off.
Read articleHow to Turn PDF Pages into Images
How to render each page of a PDF as an image, and how to pick the resolution and quality that fit your use.
Read articleUUID v4 vs v7: Which Should You Use?
v4 is fully random and v7 is time-ordered - here is how they differ and why v7 is usually the better choice for a database primary key.
Read articleWebP vs JPG: Which Is Better?
A practical comparison of WebP and JPG on size, quality, transparency, and browser support - and how to convert between them.
Read articleWhat Is a Base64 Image Data URI?
Understand what a Base64 image data URI is, how it embeds pictures inline in HTML and CSS, and when the size trade-off is worth it.
Read articleWhat Is a Unix Timestamp (Epoch Time)?
A Unix timestamp is the number of seconds since 1970-01-01 UTC - a compact, timezone-neutral way to pin down a single moment in time.
Read articleWhat Is Base64 Encoding?
Base64 turns raw binary into a small, text-safe alphabet so data can travel through channels built for text - and no, it is not encryption.
Read articleWhat Is BMI & What Do the Ranges Mean?
A plain-English guide to what BMI measures, what each category range means, and where the number falls short as a health signal.
Read articleWhat Is JSON Schema & Why Use It
Understand what JSON Schema is, how it validates the shape of your data, and why a declared schema beats scattered manual checks — with practical examples.
Read articleWhat Is Lorem Ipsum & Why Designers Use It
The story behind the scrambled Latin every designer pastes into a mockup - what it is, where it came from, and why it still works.
Read articleWhat Is URL Encoding (Percent-Encoding)?
A plain-English guide to percent-encoding: what it is, which characters are reserved or unsafe, and why every query value needs it.
Read articleWhat Makes a Good URL Slug?
The handful of rules - length, hyphens, lowercase, and stop words - that separate a clean, SEO-friendly slug from a messy one.
Read articleWhat's Inside a JWT? Header, Payload & Signature
A plain-English tour of a JWT's three parts and the standard claims you'll find in the payload.
Read articleWhy Key Order Doesn't Matter in JSON
JSON object keys are unordered by definition, so re-ordering them changes nothing — but array order is meaningful. Here's why, and what it means for comparing JSON.
Read articleWhy You Should Strip Metadata Before Sharing Images
The photos you post can quietly reveal your home address, your device, and your routine - here is why EXIF metadata is a privacy risk and how removal fixes it.
Read articleWord Count vs Character Count: What Counts?
A clear breakdown of word count versus character count - when each one matters, and exactly what a counter includes in the total.
Read articleHow to Format JSON: A Practical Guide
Turn a wall of minified JSON into something you can actually read — and validate it in the same pass.
Read articleJSON Compare Explained: How to Diff Two JSON Objects
A line-by-line text diff lies about JSON. Here's how a structural compare finds what actually changed.
Read articleJSON Validator vs Formatter: What's the Difference?
They sound interchangeable, but a validator and a formatter answer two different questions about your JSON.
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