Practical guides to the free tools on this site: what each one does, the ideas behind it, and how to use it well.
A hue shift turns every colour in an image by the same angle: blues become purples, oranges become greens, and greys never move. Here is what hue is, where the colour wheel came from, why two hue-shift methods give different results, and how to recolour an image free in your browser.
Read the guide →Everything about file compression in one place: how lossless compression works, the key techniques from Huffman to Zstandard, the history of ZIP, RAR, 7z and gzip, what each format is used for, open- and closed-source archivers, security pitfalls, and a real benchmark.
Read the guide →Why your logo gets a fuzzy halo and your photo weighs ten times too much. How JPG, PNG, GIF, WebP, AVIF, HEIC and SVG work, where each came from, which to use where, and what really happens to pixels when you resize, format by format, with real browser measurements.
Read the guide →Is Rs 25 lakh more or less than 2.5 million? Here is how the South Asian lakh–crore–arab system and the international million–billion system work, how to convert between them in your head, where the commas go, and the history behind both.
Read the guide →A hash is a short fingerprint of any text or file. Here is what that means, how MD5, SHA-1, SHA-256, SHA-512 and CRC32 differ, which one to use, and how to generate them free in your browser.
Read the guide →What does 192.168.1.10/24 actually mean, why does a /24 give you 254 devices instead of 256, and how do you split a network for staff, guests and cameras? A plain-English guide to IP subnetting, with worked examples you can check in a free IP calculator.
Read the guide →Website, Wi-Fi, vCard, WhatsApp, Micro QR, rMQR, static or dynamic: "QR code" covers a whole family. This encyclopedia explains how QR codes work inside, every symbol type and content type, how to design and print them, how to stay safe, and how to make your own free.
Read the guide →Most stolen accounts are not hacked by geniuses. They are opened with passwords that were short, predictable, or reused. Here is how attackers actually guess passwords, what makes one strong, and how to create a strong one in seconds.
Read the guide →A 12 MB scan can drop below 1 MB, and a small text PDF can grow nearly 30 times larger, using the same "compress" button. Here is why, how to choose the right compression level, and how to shrink a PDF in your browser without uploading it.
Read the guide →Your search result is the first thing people see of your page. Here is what a title tag and meta description actually do, why there is no exact character limit, and a five-step workflow for testing yours with a free SERP preview before you publish.
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