Ohm

Ohm is a Chrome extension that brings back the cosmetic filtering capabilities that uBlock Origin users lost when Google's Manifest V3 restrictions rolled out. If you relied on custom rules to hide engagement metrics, promoted posts, comment sections, follower counts, or other visual annoyances on websites, and you found those rules suddenly stopped working in Chrome, Ohm is built to fill that gap. It converts uBlock Origin format filter rules into a minimal Chrome extension that only requests permissions for the specific hosts you target, not blanket access to every site you visit. The approach keeps the extension lightweight and avoids the permission creep that larger content blockers have accumulated over time.

The project offers two paths depending on how much control you want. There's a prebuilt extension you can install directly from the Chrome Web Store, which ships with a curated set of common filters for popular sites that most users find annoying. And there's a build your own option where you paste in your own filter list, pick which domains it applies to, and Ohm generates a personal extension scoped to exactly those domains. The build your own flow runs entirely in your browser tab. You paste the rules, click a button, and download a ZIP file containing a complete Chrome extension ready to side load via Developer Mode. No server involved, no account required, no data ever leaving your machine. You could do the entire process offline once the page is loaded.

Under the hood, Ohm supports procedural cosmetic filters that go beyond simple CSS selectors. You can use operations like remove to delete elements entirely rather than just hiding them, remove class to strip specific CSS classes that trigger unwanted behavior, has text to target elements containing certain words regardless of their HTML structure, and upward to select ancestor elements based on child matches when the element you want to hide is nested inside a container you need to target. These procedural filters let you target page elements by their content or structure rather than relying on fragile class names that websites change frequently during redesigns and A/B tests. If you've ever written a filter rule that broke a week later because the site renamed a CSS class or restructured their markup, you understand why procedural selectors matter for long term maintainability.

All processing happens locally in the browser. The extension doesn't phone home, doesn't collect analytics, and doesn't report what filters you're running or which sites you're modifying. This is relevant if your filter list reveals sensitive preferences about what kind of content you find objectionable or distracting. If you're hiding certain types of content or blocking specific UI elements, that information stays on your machine rather than being logged by a third party service that might sell behavioral data or get subpoenaed. The privacy model is simple because there's nothing to exfiltrate in the first place.

The build your own tool generates a complete extension package including manifest.json, content scripts, and icons. The output is a standard Chrome extension folder structure that you can load via Developer Mode for personal use or zip up and distribute to others if you want to share your filter set. Each generated extension only requests host permissions for the domains specified in your filter rules, which keeps the permission footprint minimal. You're not granting access to all URLs or all your browsing data, just the sites you explicitly want to filter. This is a meaningful improvement over extensions that request blanket permissions upfront and then promise not to abuse them.

This is clearly aimed at power users who were already comfortable writing or importing uBlock cosmetic filter syntax. It's not trying to be a general purpose ad blocker for people who just want to click install and forget about it. If you don't know what a cosmetic filter is, why you'd want one, or what the host##selector syntax means, you're probably not the target audience. But if you've been frustrated watching your carefully tuned filter list stop working in Chrome after the Manifest V3 transition, and you don't want to switch browsers entirely or use a full content blocker that demands deep permissions you're not comfortable granting, Ohm solves the narrow problem it claims to solve without expanding scope into features you didn't ask for.

The tool is MIT licensed and fully open source. You can read every line of code on GitHub before you install anything, which matters if you're security conscious about what runs in your browser. There's no pricing because there's nothing to pay for. The prebuilt extension and the build tool are both free, there's no premium tier that unlocks extra features, and no account or registration is required to use any of it. The tradeoff is that you're on your own for support. There's no company behind this, just an open source project maintained by a solo developer in their spare time. If something breaks or you need help writing filter rules, the GitHub issues page is your only recourse. That's acceptable for a free tool, but worth knowing upfront.