Slack is an American cloud-based set of proprietary team collaboration tools and services, founded by Stewart Butterfield. Slack began as an internal tool used by his company, Tiny Speck, in the development of Glitch, a now-defunct online game. The name is an acronym for “Searchable Log of All Conversation and Knowledge”.

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While no longer using an IRC backend, Slack offers many IRC-like features, including persistent chat rooms (channels) organized by topic, private groups and direct messaging. All content inside Slack is searchable, including files, conversations, and people. On the free plan, only the 10,000 most recent messages can be viewed and searched. Users can add emoji buttons to their messages, which other users can then click on to express their reactions to messages.


Slack teams allow communities, groups, or teams to join through a specific URL or invitation sent by a team admin or owner. Although Slack was meant for organizational communication, it has been slowly turning into a community platform, a function for which users had previously used message boards or social media such as Facebook or LinkedIn groups.[ Many of these communities are categorized by topics which a group of people may be interested in discussing.


Public channels allow team members to communicate without the use of email or group SMS (texting). They are open to everyone in the chat, provided they have first been invited to join the client. Private channels allow for private conversation between smaller sects of the overall group. These can be used to break up large teams into their own respective projects. Direct messages allow users to send private messages to a specific user rather than a group of people. Direct messages can include up to nine people (the originator plus eight people). Once started this direct message group can be converted to a private channel.


Slack integrates with a large number of third-party services and supports community-built integrations. Major integrations include services such as Google Drive, Trello, Dropbox, Box, Heroku, IBM Bluemix, Crashlytics, GitHub, Runscope, Zendesk, and Zapier. In December 2015, Slack announced their app directory, consisting of over 150 integrations that users can install. In March 2018, Slack announced its partnership with the financial and human capital management firm Workday; Adding to Slack’s list of plugins. This integration allows Workday customers to access features from directly within the Slack interface.


Slack provides API to users to create applications and to automate processes, such as sending automatic notifications based on human input, sending alerts on specified conditions, and automatically creating internal support tickets. The Slack API has been noted for its compatibility with many types of applications, frameworks, and services.


Slack provides mobile apps for iOS, Android, and Windows Phone (beta), in addition to their web browser client and electron desktop clients for macOS, Windows, and Linux (beta). Slack is also available for the Apple Watch, allowing users to send direct messages, see mentions, and make simple replies. It was featured on the home screen of the Apple Watch in a 2015 promotional video. Slack has been made to run on a Super Nintendo Entertainment System via Satellaview.

Business model

Slack is a freemium product, whose main paid features are the ability to search more than 10,000 archived messages and add unlimited apps and integrations. They claim support for an unlimited number of users. When freeCodeCamp attempted to switch its community of over 8,000 users to Slack in 2015, however, they experienced many technical issues and were advised by Slack support to limit their channels to “no more than 1,000 users (ideally more like 500)”. That specific limit no longer applied by January 2017.

We at AppsForMyPC have tested and used Slack and it worked pretty smoothly 🙂 🙂