Guides

The explanation behind each tool: what the settings actually do, which format to pick, and how to hit a file size limit without wrecking the picture.

Image guides

How to Compress an Image to a Target File SizeUpload forms want 100KB or 200KB and nothing larger. Here is how to hit a number instead of guessing at it.9 min read WebP vs AVIF vs JPEG vs PNG: Which Format Should You Use?Four formats, four different jobs. What each one is actually good at, and when the newest is the wrong choice.7 min read Social Media Image Sizes (2026): Every PlatformDimensions and aspect ratios for every major platform, and the crop settings that stop faces being cut off.7 min read HEIC to JPG: Why iPhone Photos Won't Open, and How to Fix ItiPhones save HEIC. Windows, email and upload forms often can't read it. Why, and what to do about it.8 min read How to Remove an Image Background CleanlyAutomatic cutouts are excellent on some subjects and poor on others. Which is which, and how to fix the edge.9 min read How to Reduce Image File Size Without Losing QualityTruly lossless saves less than people hope. Here is where the real savings are, and what they cost.9 min read How to Remove a Watermark from an ImageSome watermarks can be removed exactly; others can only be guessed at. The difference is transparency.9 min read

Or go straight to the image tools.

Web widgets guides

Why Your Favicon Isn't Showing in Google SearchGoogle has specific favicon rules, and a 16x16 ICO satisfies none of them. What it actually looks for.9 min read QR Codes That Actually Scan: Size, Error Correction and PrintMost QR failures are size, contrast or a missing quiet zone. The numbers that make one scan first time.10 min read Image Optimization for Core Web VitalsImages are usually the LCP element and the main source of layout shift. The fixes, ordered by effect.9 min read

Or go straight to the web widgets tools.

Text guides

How Many Pages Is 500, 1,000 or 2,000 Words?Word count to pages, both spacings, plus how long the same text takes to read aloud.7 min read Naming Conventions: camelCase, snake_case, PascalCase and kebab-caseWhich convention each language expects, and the one case where the choice affects SEO.6 min read How to Compare Two Files and Read the DifferenceLine, word or character comparison answer different questions. Picking wrong hides the change you wanted.8 min read

Or go straight to the text tools.

Why these exist

Every tool on Zyff has settings, and a setting is only useful if you know what it trades away. The quality slider on the compressor is a choice about how much detail to discard; the fit mode on the resizer decides whether your image gets cropped or letterboxed; the error correction level on a QR code trades damage tolerance against how small the code can be printed. These guides are the explanations behind those choices.

They are written to be useful whether or not you use the tools. Where a number is quoted — a size limit, a quality threshold, a recovery percentage — it comes from what the tool actually enforces rather than from a round figure that reads well. Every guide ends by pointing at the tool that does the job, and every tool page links back to the guides that explain it.