Practical guides
Clear explanations of everyday digital tasks: what the options mean, which settings work, and which mistakes to avoid. Each guide links to a free tool that does the job in your browser.
All guides
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How to Reduce Photo File Size: What Really Works for 100 kB, 200 kB and 500 kB
Lowering the quality alone barely helped our phone photos, and at higher settings they even got bigger. We measured which combination of size and quality fits common upload limits.
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How to Count Words and Characters: Why Counters Disagree, SMS Limits and Reading Time
The same sentence can have 8, 10 or 12 words, depending on who counts. We tested how browsers split words, counted our own guides in four languages and worked out when an SMS shrinks from 160 to 70 characters.
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How to Check Color Contrast: WCAG 2.2 Ratios, HEX, RGB and HSL Explained
Why white text on a bright blue button can fail, why HSL lightness is misleading and which gray is the lightest you can use on white. We calculated the WCAG 2.2 contrast ratios for common colors.
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JSON Errors Explained: How to Find and Fix Invalid JSON
Trailing commas, single quotes, comments, an invisible BOM: we fed 26 broken JSON snippets to Chrome, Python and PHP and wrote down what each one reports. Here is how to read the message and fix the real cause.
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How to Merge and Split PDF Files Without Uploading Them – and What Gets Lost
Combining and splitting PDFs is easy, but what happens to bookmarks, form fields, links and file size? We tested it with real documents and explain how to do it privately in your browser.
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How to Make a QR Code That Always Scans: Size, Contrast and Error Correction
We generated QR codes, covered them with logos, lowered the contrast, shrank them and removed the margin, then tried to decode them. Here is what makes a QR code reliable and what quietly breaks it.
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JPG, PNG, WebP or AVIF? How to Choose the Right Image Format
We encoded the same photos as JPG, WebP and AVIF at equal visual quality and compared the file sizes. Here is what each format is good at, when PNG is still the right choice, and how to convert your images.
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How to Extract Text from an Image: 8 Tips for Accurate OCR
We ran our free OCR tool on test images with tiny text, tilted lines, shadows and blur. Here is what really breaks text recognition, how to prepare a photo or screenshot, and how to check the result.
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How to Create a Strong Password: Length, Randomness and What NIST Recommends
Why a long random password beats a short complicated one, how many bits of entropy you actually need, what the 2025 NIST guidelines changed, and how to create and store passwords safely.
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How to Write a Title Tag and Meta Description That Get Clicks
What Google actually does with your title and description, why pixel width matters more than the number of characters, and a practical checklist with before-and-after examples.
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How to Calculate Percentages: 7 Formulas with Worked Examples
Percent of a number, percentage change, reverse percentages, VAT, stacked discounts and percentage points: each formula with a worked example and the traps that catch even careful people.
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Persian, Islamic and Gregorian Calendars: How They Work and How to Convert Dates
How the Solar Hijri, lunar Hijri and Gregorian calendars count years, months and leap days, why a converted Islamic date can be off by one day, and how to convert dates reliably.
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How we write our guides
Every guide starts from a real question and is checked against primary sources such as official standards and documentation, which are listed at the end of each article. Numbers in examples are calculated, not estimated, and measurements are made with the tools described.
We update a guide when standards, browsers or recommendations change, and correct mistakes as soon as we learn about them. More about our process: Editorial policy