SilentBlock

Free, silent ad blocker for Chrome (Manifest V3). No ads, no nags, no subscriptions.

SilentBlock 2.0 compiles EasyList, EasyPrivacy, the uBlock Origin filter lists and the EasyList Cookie List into Chrome's native blocking engine at build time. It ships them with the extension and never downloads rules at runtime.

What it does

Layer	How
Network blocking	~21,700 declarativeNetRequest rules (from ~120,000 filters; the ~100,000 plain ||domain^ filters fold into a few dozen rules). Chrome enforces them itself, so no page script runs until it has been checked.
Stand-ins	Blocked Google Analytics, Tag Manager, gtag, GPT and AdSense scripts are swapped for local stubs, so "track the click, then navigate" links and anti-flicker snippets still work.
Generic hiding	The page reports its class and id names, and the service worker injects CSS for the ~27,500 generic ad and cookie-banner selectors that match. Nothing is parsed per frame for the rest.
Site-specific hiding	~28,000 hostnames with their own hide and restyle rules, injected per frame as it loads.
Anti-adblock	~8,200 site-specific scriptlets (uBO semantics: set-constant, abort-on-property-read, prevent-setTimeout, json-prune and 30 others), run in the page before its own scripts, only on the sites listed.
Pop-ups and tab-unders	New tabs a page opens are followed for their first few hops and closed if they land on one of ~3,000 $popup hosts. A tab sent to an ad right after the page reopened itself in a new tab is put back.
Malware and scams	uBO Badware, URLhaus, the Phishing URL Blocklist and DurableNapkin's scam list: ~46,000 hosts blocked outright, plus ~36,000 individual phishing and malware page URLs checked on every navigation. A listed page gets a warning with "Back to safety" and "Continue anyway". This layer stays on for paused sites. No API keys and no lookups: every check is local.
Nag walls	"Kill nag wall" in the popup removes an anti-adblock overlay on demand, or on every visit with "Always on this site".

Every piece of CSS is injected as a user stylesheet: pages cannot see it, override it or block it with CSP. On ordinary sites SilentBlock patches no page APIs at all.

Using it

The toolbar icon's colour tells you what happened on the page in front of you:

Colour	Meaning
Slate blue	Nothing on this page needed blocking (also the brand colour)
Green	Protected: ads and trackers blocked
Amber	Pushy site: a pop-up, tab-under or nag wall was dealt with
Red	A known malware, phishing or scam host was blocked
Grey	Paused on this site, or protection is off

The popup explains the colour and shows a live count. Settings can keep the icon plain blue.

• Protection turns everything on or off.
• Block on this site pauses SilentBlock on the current site and its subdomains. This is also the fix when a site breaks: paused sites get no rules, no CSS and no scripts.
• Settings has the filter categories (ads, trackers, cookie banners), the paused and nag-wall site lists, the blocked-count badge, and settings export/import.

Pausing a site also covers tag debugging: pause the client site to let GTM preview and Tag Assistant load there. The Google Ads, GA4, GTM, Meta, LinkedIn and Microsoft consoles, and vendor dashboards such as Hotjar and Sentry, are excepted in filters/silentblock-core.txt so they work out of the box.

Install

1. Download SilentBlock-<version>-chrome.zip from the latest release and unzip it somewhere permanent, or build it yourself (below) and use dist/chrome.
2. Open chrome://extensions, turn on Developer mode, click Load unpacked and pick the folder.
3. If you had SilentBlock 1.x loaded from another folder, remove it. Chrome gives each unpacked folder its own extension id, so the two would both run. Settings do not carry across folders, so re-add any paused sites.

Chrome 120 or later. A Firefox build (dist/firefox) is produced and passes web-ext lint, but only the Chrome build is tested.

Development

Requires Node 22.2+. The checkout must live on a local disk, not Google Drive (npm writes zero-byte files there).

npm install
npx playwright install chromium   # used by the build to validate selectors and regexes
npm run build                     # -> dist/chrome, dist/firefox, dist/build-report.json
npm test                          # unit tests (compiler, settings)
npm run test:e2e                  # Playwright: the real build in headless Chromium
node scripts/verify-load.mjs      # load dist/chrome over CDP and report Chrome's own error
npm run check                     # all of the above
npm run package                   # -> release/SilentBlock-<version>-{chrome,firefox}.zip

npm run build:fast skips the browser validation. Only use it while iterating: Chrome refuses to load the whole extension if a single regex rule is one it rejects, and the full build is what catches those.

Layout

filters/
  lists.json               list registry: id, category, file, upstream URL, licence
  upstream/*.txt           committed snapshots of the upstream lists (npm run lists:update)
  silentblock-*.txt        SilentBlock's own filters (core exceptions, extras, self-test)
scripts/
  build.mjs                lists -> DNR rulesets, cosmetic data, scriptlet buckets, manifests
  lib/                     parser, network/cosmetic/scriptlet compilers, validation
src/
  manifest.json            base manifest (version and rulesets are filled in by the build)
  background/              service worker: state, apply (reconcile), cosmetic injection
  content/                 token reporter, Facebook sponsored posts, nag-wall remover
  scriptlets/library.js    MAIN-world scriptlets, embedded into each bucket by the build
  resources/               redirect stubs (GPT, gtag/GTM, analytics.js, noop files)
  icons/                   toolbar icons per state, rendered by scripts/icons.mjs from assets/icons/
  popup/, options/, warning/, shared/
test/unit, test/e2e, test/fixtures

How settings apply

src/background/apply.js reconciles the browser with the saved settings: which rulesets are enabled, one dynamic allowAllRequests rule for paused sites, and every registered content script, each with excludeMatches built from the paused list. It runs on install, update, browser start and after each settings change. Settings are never reset on update, and 1.x settings are migrated.

Updating the filter lists

npm run lists:update   # refresh filters/upstream/*.txt (keeps the old snapshot if a download looks wrong)
npm run check

Review the build report's rule counts before committing. The build fails if the total goes past the 30,000 static rules Chrome guarantees every extension.

Adding SilentBlock's own filters

Use ABP/uBO syntax in filters/silentblock-*.txt. Network rules should be $third-party unless there's a reason not to be. filters/silentblock-selftest.txt only targets the reserved .test TLD and drives the end-to-end tests. Leave it in.

Releasing

npm run bump -- minor        # or patch / major / x.y.z; updates package.json + CHANGELOG
npm run check && npm run package
git add package.json package-lock.json CHANGELOG.md
git commit -m "Release vX.Y.Z" && git tag vX.Y.Z && git push --follow-tags

Pushing the tag runs .github/workflows/release.yml: build, full tests (Chrome and a Firefox smoke test), a GitHub release with the Chrome, Firefox and source zips, then a submission to each store it has credentials for. Every store reviews the upload before users get it.

Store	Item	Credentials
Chrome Web Store	accdpphckockpflaggbplikpmaknioao	None stored: keyless login from GitHub Actions to the cws-publisher service account (Workload Identity Federation in clicktrack-505800, tags only)
Firefox (AMO)	silentblock@local	Repo secrets AMO_JWT_ISSUER, AMO_JWT_SECRET
Microsoft Edge	hhdolnhpfeeipbomjfkalbhegkakbkmo	Repo secrets EDGE_PRODUCT_ID, EDGE_CLIENT_ID, EDGE_API_KEY

A store with no credentials is skipped. To retry a store, or publish an existing release after adding credentials, run the Publish workflow by hand: gh workflow run publish.yml -f tag=v2.0.1 -f stores=firefox (stores defaults to all three). The same scripts run locally: npm run package, then npm run publish:chrome (signs in through your gcloud login), publish:firefox or publish:edge with the variables above. npm run store:status shows what Chrome has. Listing text and images: docs/store-listing.md and npm run store:art.

Filter lists and licences

List	Licence
EasyList, EasyPrivacy, EasyList Cookie List	GPL-3.0 or CC BY-SA 3.0
uBlock filters (main, quick fixes, unbreak, privacy, cookie notices, badware)	GPL-3.0
Malicious URL Blocklist (URLhaus data)	CC0 / MIT
Phishing URL Blocklist	CC BY-SA 4.0 (sources: OpenPhish, PhishTank, IPThreat)
Scam Blocklist by DurableNapkin	MIT

SilentBlock itself is licensed under the GNU GPL v3.0 or later. The bundled filter lists keep their own licences, listed above. Privacy policy: PRIVACY.md.