Slack

Comments: Slack is a very good tool with many add-ons that can help your business with communication, reminders, etc. The library of add-ons is growing.
The only thing is that I wish the search was a little bit better, you often find irrelevant hits and it is a bit hard to exclude channels or people in your search.

Pros: How easy it is to use.
It is easy to chat with other members in the organization, it is easy to start small chat groups, for more permanent groups you can start channels, both public and private.
It has both voice calls and video calls that are fast and smooth with great quality.

Cons: It is a bit harder to cooperate with other companies, where skype is available for anyone and you can easily add any contact, in slack you need an administrator to add a quest to the workspace. a good thing is that for each paid license you have in the company you can invite 5 guests that have access to a single channel(single-channel guest). a small con is that you need to pay a license for any guest that need access to more than one channel(multi-channel guest) The search function could offer a few more options

Comments: I actually enjoy Slack. It is fun to use, and I like much more than sending an email.

Pros: Slack really allows us to communicate effectively based on group or subject. We can communicate directly in the General chat, directly, or in any number of specialized group channels. Each team has their own channel, and if needed, that channel can be locked to prevent other teams from entering. Most are open channels that allow for any of our teams to come in and converse on the subject titled. One our favorite things to use are external apps. I love that Slack will pop up an upcoming appointment or if we need a meeting in say Zoom, I can just type /zoom and it will generate a Zoom link and we can all join in. We are on the free tier, so with the higher level tier, you can get conferencing and a wealth of other features added in. The free level serves us very well. We use email integration also, so important emails and even things like weather alerts pop up as a Slack notification. It is really a great service.

Cons: Can be confusing to use if you are not used to chat systems such as Hangouts or WhatsApp though. The idea of a separate room, or Group chat, confuses some, but once they see how things work, it is a non-issue.

Comments: a great free/paid, GDPR compliant option for company instant messaging

Pros: Slack offers free versions of it's software which were suitable for our business and therefore saved us money versus competitor instant messaging products. Slack is also GDPR complaint so ticked our boxes in terms of what we needed. The interface is also simple to use and intuitive, as well as not being too cluttered. It offers both group chats, company wide groups and personal chats. Slack also has great integration possibilities with other apps such as dropbox, or client relationship managers, which is useful for sharing information. it also allows you to create polls and share gifs etc, and has clear pop up notifications and email updates.

Cons: -limited naming allowances for channels (e.g. no spaces end no capital letters) which can make it hard to think of obvious names for some groups
-the gif insertion is a strange system, (have to type /giphy [text] and then it will give you one suggestion of a gif and you have to shuffle if you want a different picture, rather than being able to choose)
-the way of responding to a certain message and creating a new chain can be complex to some in the team

Comments: Overall, we use this tool as a team all day long and it works well for what we need. On occasion it "glitches," but that is rare.

Pros: Slack is easy to use, it is easy to chat in a group, set up special channels and have private chats. It does have a calling feature, with share-screen ability. I especially like that you can mute or change the sound features of each channel or group, and that you can pause all notifications for a period of time. It's easy to see when team members are on and available to talk, which is important as we have an all remote team.
Service is great with a Slack help feature that allows you to ask questions and get immediate help from Slackbot. Polly is a great tool for polling, very easy to use.

Cons: Slack can be glitchy at times, rarely, but it is irritating. It will show as if I am not on when I am. Other times I will miss comments because it just didn't notify me. This is not just me, but the entire team will have these issues on occasion. Again, it's rare, and a simple log out and back in are all that's needed to get it working again.
The calling feature is great in many ways, but there are times when the quality is not the greatest and we get disconnected. Again, rare; and it might not even be a Slack issue - maybe internet glitches?

Comments: Before using Slack, we had to wait for people to answer emails or use text messages or chat apps. None of it was organized into a company-wide system where you can have multiple conversations with different people. Slack is the perfect solution for quick communication that doesn't need to be saved forever.

Pros: Slack is very simple to set up and use and allows us to quickly message our team members who all work remotely. It's a great tool for sharing links, getting answers to simple questions, and also sharing fun things in the Random and General Channels. We've got a few different Channels we use with our 21 users who are a combination of employees and contractors. We also use Google Drive, so that is integrated into Slack.

Cons: We've got the free plan, so we have messages that are now archived that we can't access. Considering it's free, it's not much of a con.