Mailboxes and Messengers

Gmail https://support.google.com/mail/answer/7190?hl=en
Yahoo https://www.lifewire.com/search-messages-yahoo-1174487
Outlook https://support.microsoft.com/en-us/office/learn-to-narrow-your-search-criteria-for-better-searches-in-outlook-d824d1e9-a255-4c8a-8553-276fb895a8da
Yandex https://yandex.ru/support/mail/web/letter/query-language.html
Mailbird https://support.getmailbird.com/hc/en-us/articles/360042425014-Advanced-Search-queries-and-UI
Mail (Mac OS) https://support.apple.com/en-au/guide/mail/mlhlp1003/mac
Front https://help.front.com/t/632499/how-to-search-in-front
Postbox https://support.postbox-inc.com/hc/en-us/articles/202200180
Protonmail https://protonmail.com/support/knowledge-base/search/
Google Workspace (Hangouts, Groups, Chat, Voice) https://support.google.com/vault/answer/2474474?hl=en#zippy=%2Cgoogle-voice-search-operators%2Cgoogle-chat-search-operators

Cloud storages

Google Drive https://support.google.com/vault/answer/2474474?hl=en

Operation systems

MacOS https://support.apple.com/guide/mac-help/narrow-search-results-mh15155/mac
Windows https://thegeekpage.com/windows-10-advance-search-tricks-cheatsheet/#Search_by_File_extension

Linux (find command cheat sheet) https://devhints.io/find

Search engines

Google https://www.indeed.com/career-advice/finding-a-job/google-search-operators#:~:text=Google%20Search%20operators%20are%20combinations,Punctuation%20such%20as%20quotation%20marks
Yandex (also works with Yandex Images Search) https://seosly.com/yandex-search-operators/
DuckDuckGo https://help.duckduckgo.com/duckduckgo-help-pages/results/syntax/
Bing https://seosly.com/bing-search-operators/#:~:text=Bing%20search%20operators%20are%20special,your%20online%20life%20way%20easier
Baidu http://www.baiduguide.com/baidu-seo-guide/baidu-search-operators/
Ask https://askhelp.extension.org/advanced-search-options/
Naver http://seoseminkorea.blogspot.com/2015/03/naver-seo-naver-advanced-operators-list-2015.html
AOL https://help.aol.co.uk/articles/Advanced-Search

Social media

Twitter https://www.tweetbinder.com/blog/twitter-advanced-search/
YouTube https://seosly.com/youtube-search-operators/
Reddit https://www.reddit.com/wiki/search/

Content analysis

BuzzSumo http://help.buzzsumo.com/en/articles/1633294-web-content-analyzer-advanced-search-operators

Professionals communities

Linkedin https://booleanstrings.com/linkedin-search-operators/

Coding

Github https://docs.github.com/en/github/searching-for-information-on-github/searching-on-github/searching-code
Gitlab https://docs.gitlab.com/ee/user/search/advanced_search.html
Bitbucket https://confluence.atlassian.com/bitbucketserver/bitbucket-search-syntax-814204781.html

Job searching

Stack Overflow Jobs https://stackoverflow.com/help/advanced-search-parameters-jobs

Code

Github Gist https://gist.github.com/santisbon/2e1e9c69b58bdf4c9624219a44d40d83

Productivity and project management

Trello https://help.trello.com/article/808-searching-for-cards-all-boards
Slack https://slack.com/intl/ru-ru/blog/productivity/shrinking-the-haystack-how-to-narrow-search-results-in-slack
Evernote https://help.evernote.com/hc/en-us/articles/208313828-Use-advanced-search-syntax
Jira https://support.atlassian.com/jira-software-cloud/docs/advanced-search-reference-jql-operators/
Todoist https://todoist.com/en/help/articles/introduction-to-filters https://blog.doist.com/todoist-filters/
Shortcut https://help.shortcut.com/hc/en-us/articles/360000046646-Searching-in-Shortcut-Using-Search-Operators

IOT search engines

Shodan https://help.shodan.io/the-basics/search-query-fundamentals
Censys https://censys.io/ipv4/help/examples?q=&
FOFA https://fofa.so/ (click the button below search field)

Marketplaces

Alibaba Cloud https://www.alibabacloud.com/help/doc-detail/29060.htm

Maps

Mapy.cz https://napoveda.seznam.cz/en/advanced-search-and-gps-coordinates/
Arcgis https://enterprise.arcgis.com/en/portal/latest/use/advanced-search.htm

Images

Pics.io https://help.pics.io/en/articles/1811657-advanced-search

Libraries

PubMed https://library-guides.ucl.ac.uk/pubmed/advanced-search

Customer support

ZenDesk https://support.zendesk.com/hc/en-us/articles/203663226

News/RSS

Feedly https://feedly.helpscoutdocs.com/article/82-what-are-the-advanced-search-operators

Databases

Aleph https://docs.alephdata.org/guide/search/advanced-search-methods

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Dork collections lists

https://github.com/cipher387/Dorks-collections-list