Want to filter out some useless, spammy or offensive sites from Google, DuckDuckGo, Startpage.com, Bing and Yahoo search results? Just click "block" to reduce a site's hits to a one-line notation, or hide it completely. No typing required.
For a one-minute video overview, and a detailed description of the script, please see the following page: http://www.jeffersonscher.com/gm/google-hit-hider/
Google Chrome users: Install the Tampermonkey extension for Chrome BEFORE installing this userscript.
Firefox 57+ users: Install the Violentmonkey extension or the Tampermonkey extension for Firefox BEFORE installing this userscript. (The script is partially compatible with the new Greasemonkey but it's not quite there yet.)
Firefox 52 ESR/Waterfox Classic users: If you are using the legacy Greasemonkey extension (version 3.11), you need to manually edit version 2.1.5 or later. See: this recent thread.
Other Browsers: I have no idea...
Disclaimer: Google search is a very complex application, so there is no guarantee that this script will work for you. The author is not responsible for you missing a result you might have liked to see, or other malfunction of the script. Use at your own risk.
If you need to extract your block list from before Firefox 57 and move it to Tampermonkey or Violentmonkey, or to the newest Greasemonkey, please see: https://openuserjs.org/scripts/jscher2000/Google_Hit_Hider_by_Domain_(Search_Filter_Block_Sites)/issues/Extract_Block_List_from_Greasemonkey_Storage
You can find explanations of most functions on my site here: http://www.jeffersonscher.com/gm/google-hit-hider/. If that does not help, please use the "Issues" link on the toolbar just below the Install button.
v2.2.1 - Bug fixes for Google Images and Yahoo
v2.2.0 - Bug fixes for DuckDuckGo and sizing of Export/Import
v2.1.9 - Bug fixes for hiding/unhiding Twitter carousel
v2.1.8 - Style fixes for Startpage and Ecosia
v2.1.7 - Fixes for updated Google and Startpage layouts
v2.1.6 - Restore Manage Hiding menu item for Tampermonkey/Violentmonkey/FireMonkey
v2.1.5 - Initial FireMonkey compatibility; fixes for custom CSS feature
v2.1.4 - Fixes for block button in the cite line on Google, and glitch on Baidu
v2.1.3 - Updates for Google Images; syntax corrections per Tampermonkey linter
v2.1.2 - Fixes for Google "cite above" layout(s), Google carousels, Startpage, and Bing
v2.1.1 - Adapt to Google Images changes; handle ftp: result URLs
v2.1.0 - Bug fix for users who customized button captions; added start.duckduckgo.com
v2.0.9 - Ecosia web search; Add All feature to immediately block all unblocked domains on the page (display the list you want them added to first)
v2.0.8 - Adapt to new Google image results layout
v2.0.7 - Update for new results structure on Startpage.com (thread).
v2.0.6 - Improve Manage Hiding dialog performance with long block lists (thread).
v2.0.5 - Bug fixes for image search and do not block partial IPv4 addresses (thread); streamline list-generation code; (v2.0.4 not posted here) Adapt to Bing change on Firefox, exclude Recaptcha frames, allow importing 1-character domains.
v2.0.3 - Minor fixes for Google Images, Startpage.com, Bing (Bing's still broken on Chrome)
v2.0.2 - Emergency fixes for Startpage.com (still some weird layout issues...); minor fix for Adwords results page
v2.0.1 - Partial fix for breakage in Bing on Chrome
v2.0.0 - Fixes and added domain support for DuckDuckGo; some code streamlining
v1.9.9 - Fix bug with ~ button and integrate .tld option
v1.9.8 - Initial support for .tld blocking (e.g., use Import to add ru.tld to block .ru results); fixed buttons for Yandex.com (for Tampermonkey; Violentmonkey can't apply the script to Yandex.com)
v1.9.7 - Fix List Util button (remove use of initMouseEvent)
v1.9.6 - Support AdWords testing results page; MyWOT and other bug fixes
v1.9.5 - Tweaks for Google, Google Images, and Bing results page changes
v1.9.4 - Fixes for Baidu blocking (see: Baidu works not very well)
v1.9.3 - Baidu web results support (see: Baidu Support (v1.9.3+), fixed missing GHHbD button on Google image results
v1.9.1 - Replace GM_addStyle (hat tip: problems with non gm engines
v1.9.0 - Greasemonkey 4 compatibility (lightly tested, subject to glitches!)
v1.8.3 - fixed missing block buttons on Yandex.com, added support for Qwant web results, conformed license code
v1.8.2 - import can completely replace your current list, tweaks for Yahoo results
v1.8.1 - ability to remove subdomains from partial domain in block form; block featured snippets
v1.8.0 - minor tweak for Google; compatibility with uAutoPagerize on Yahoo and Yahoo Japan
v1.7.9 - initial support for Searx.me metasearch (general/news), minor CSS corrections
v1.7.8 - fix bugs on Google Image results
v1.7.7 - find real domain in Startpage.com highlight links (per the issue: "Inaccurate block popup."), restore GHHbD button on Google Image results
v1.7.6 - adjust placement of the block button to avoid overlaying title or WOT icon
v1.7.5 - work around script change on Google images, initial support for Yandex.com web search
v1.7.4 - fix unblocking bug on Google image search
v1.7.3 - adapt to style change on Google image search
v1.7.2 - tweaked style rules for block button in the cite line on Google
v1.7.1 - adapt to layout change for top result in some Google searches
v1.7.0 - support for Bing and Yahoo web search, various fixes for Google Images, GoogleMonkeyR, style rules
v1.6.9 - partially restore blocking on Google Images (perma-ban results are blank, not deleted)
v1.6.8 - override style rule on DuckDuckGo that truncated the block dialog
v1.6.7 - fixed typo affecting the Autopagerize extension (http://fox.2ch.net/test/read.cgi/poverty/1439688850/99)
v1.6.6 - quick fix for changes to Google web results layout of 7/22/2015
v1.6.5 - updated for current Google images layout, remove blank spots in GoogleMonkeyR layout, fix +site/-site
v1.6.4 - recognize URLs after Google modifies them to tracking links
v1.6.3 - changed @include's from .tld to .*, added detection for In-depth articles section of web results
v1.6.2 - fixes for new DuckDuckGo results layout