Guides
Short, practical explanations of the problems our tools solve, each with the fix and the tool to check it.
Guide100 useful websites, sorted by what you need them forA list of 100 useful websites for images, files, writing, learning, code, site owners, privacy and everyday tasks. Every link checked in October 2026.Guide24 useful web tools that work without an accountA list of useful web tools you can open and use right away: no account, no install, no watermark. Grouped by images, data, site checks and everyday jobs.GuideHow to build a campaign URL for Google Analytics 4How to build a campaign URL for Google Analytics 4: which UTM parameters to add, a worked example, where the data shows up in GA4, and when not to tag.GuideHow to Compress Images for the Web Without Losing QualityPick the right format, resize before you compress, and choose a sensible quality setting. A short, practical guide to smaller images that still look sharp.GuideHow to Fix a Link Preview Image That Is Not ShowingWhy your link shows no image on LinkedIn, X, Slack or WhatsApp, and how to fix the og:image tag — including the cache that keeps the old preview alive.GuideHow to generate a JSON Schema from JSONHow to generate a JSON Schema from a JSON sample, and the six things a generator cannot know that you should fix by hand before you use the schema.GuideHow to make a cubemap skybox in UnityHow to turn six face images or a 360 panorama into a cubemap skybox in Unity: import settings, the skybox material, and fixes for seams and flipped faces.Guideog:image size and format requirements per platformThe og:image size that works on every platform is 1200 x 630 pixels. Here are the limits for Facebook, LinkedIn, X, WhatsApp and Slack, and the tags to add.GuideOpenGL vs DirectX Normal Maps: Which One Your Engine NeedsOpenGL and DirectX normal maps differ only in the green channel. See which format Unity, Unreal, Godot and Blender expect, and how to convert between them.GuideUnity Mask Maps Explained: How to Pack Metallic, AO and SmoothnessWhat goes in each channel of a Unity HDRP mask map, how URP differs, how to turn roughness into smoothness, and how to pack the texture for free.GuideUTM Parameters Explained: A Naming Guide That Keeps Reports CleanWhat the five UTM parameters mean, naming rules that keep analytics reports clean, worked examples, and the mistakes that quietly corrupt campaign data.Guideutm_source and utm_medium values: a reference listA reference list of utm_source and utm_medium values, with the Google Analytics 4 channel each medium maps to and the values that end up as Unassigned.GuideWhat is JSON Schema? Examples you can copyJSON Schema explained with examples: what a schema looks like, the keywords you will use most, and where it is used, from API validation to LLM outputs.GuideWhat Is llms.txt and Should Your Site Have One?llms.txt explained: what the file is, the format it uses, a short example, how it differs from robots.txt, and an honest look at what it does and does not do.GuideWhat to put on a useful links pageHow to build a useful links page that visitors use and search engines trust: how many links, how to group and describe them, and what to leave out.GuideWhy Is My Page Not Indexed by Google? A ChecklistA practical checklist for pages that do not show up in Google: robots.txt blocks, noindex tags, canonical mistakes, sitemap gaps and thin internal linking.