Sizes, limits, and the reasoning behind them
Reference material for the things the tools do. Written to be checked rather than skimmed, and updated when a platform changes something.
YouTube thumbnail size: 1280 × 720, and what actually gets cropped
The recommended size is well documented. What nobody tells you is how small that image gets before anyone decides whether to click it.
Every social image size that matters, in one place
Forty-eight placements across thirteen platforms. Which ones share a size, which ones cannot be reused, and why the crop is the part that bites.
How to read your engagement rate without fooling yourself
Three formulas share the name. They give very different numbers from the same post, and the flattering one is the one most people quote.
Why browser tools do not upload your files, and how to check in a minute
Every free tool site claims your files are safe. Here is what the claim means technically, and the two ways to verify it yourself.
Character limits, and the ones that truncate without telling you
Hitting the cap is the visible failure. The expensive one is the cutoff that happens hundreds of characters earlier, in the feed.
What the image quality slider actually does
Quality 80 is not "80% as good". Understanding what JPEG discards explains why 80 looks fine, 60 is often fine too, and re-saving is what kills an image.
JSON that will not parse: the six things it almost always is
A parse error names a position, not a cause. Here are the six mistakes behind nearly every one, in the order they are worth checking.
How this site serves 2,119 tools from one file
No framework, no build step, no server. What that buys, what it costs, and the three techniques that make it hold together.
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