Zulip is a chat and collaborative software created by Jessica McKellar and Tim Abbott in 2012. It was originally developed as a proprietary software by a combridege company called Zulip. Zulip can be a perfect and nice alternative to Slack or HipChat Actually right now it's the leading alternative to the above mentioned collaborative softwares.
Like slack, zulip has endless intergration with almost anything you can imagine slack has. As of this writing zulip has over 100+ intergration and since zulip is developed by a community it's intergration keeps growing each and every moment. And if you feel like there is a missing intergration you can use Zulip's own intergration to extend and add your own intergration.
A sample of zulip's supported intergrations.
Like slack having lots of active bots zulip also has a it's own pre-developed bots. This can help run automated task like reminders and if you have a bot you like in your own daily usage again you can use Zulip's own very easy API to develop those bots.
Zulip also comes with both support for web and desktop, This wide array of support added to it's popularity and the face that zulip can be self hosted by your self if you want to retain and manage your own private data. Though zulip also has a commercial support provided by the major company behind zulip.
Zulip requires a fully working email server and there are lots of other options out there that you can use if you don't have a fully working mail server yet. Zulip needs to be able to send email so it can confirm new users’ email addresses and send notifications
Alternative free outgoing mails to use with zulip
For sending outgoing email from your Zulip server, zulip highly recommend using a “transactional email” service like
Alternatively you can consider using gmail.