GridSim drops a column (x) and baseline (y) grid onto any live website, so you can see what lines up and what drifts. The best part: a bookmarklet (Safari and Chrome) you drag to your bar once, then click on any site to overlay the grid in-page, with live column and gutter controls. You can also paste a URL, check it in a real iPhone or Android frame, compare two devices, and take the grid into Figma as an overlay or grab the CSS. Free, no sign-up.

Hey Product Hunt 👋 I'm Wilfredo, I run Studio Practice (same shop as MacSim and CyberRuler). Paste any URL and it drops a column (x) and baseline (y) grid right on the live page. Check it on desktop or inside a real iPhone or Android frame, set two phones side by side to compare, then pull the grid into Figma or Sketch as a transparent overlay (or grab the CSS). The part I reach for most: the bookmarklet (Safari and Chrome). Drag it to your bar once, then click it on any site you're already looking at and the grid drops in-page, with live column and gutter controls. No pasting URLs, no leaving the page you're on. It's free, no sign-up. Would love to hear what you'd check with it, and what it should do next.

I hope you all enjoy the Bookmarklet feature!

GridSim

See any website's grid, right on the live page.

See any website's grid, right on the live page.

Forum Threads

Bookmarklet!

Forum Threads

Bookmarklet!