Flock vs Rocket.Chat
When comparing Flock vs Rocket.Chat, the Slant community recommends Rocket.Chat for most people. In the question“What is the best team chat software?” Rocket.Chat is ranked 7th while Flock is ranked 17th. The most important reason people chose Rocket.Chat is:
Rocket.Chat is available for free. It's licensed under the MIT license with source code available on [GitHub](https://github.com/RocketChat/Rocket.Chat).
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Cross-platform
They have apps for Windows, Mac, Chrome, iOS, Android and web interface. And all the chat sessions are always on sync.

Pro Clean and clutter free interface
Pro Cheaper than Slack
It is half the price of Slack and full of nice features like polls, assign to do's, etc.
Pro Very powerful integration APIs
Unlike its rivals, it not only allows you to receive events, but also allows you to push content to it and receive various user action events.
Pro No IT team required for setup
Moving a team or organization to flock does not require any setup from the company's IT team. At max, what might be required would be to whitelist their domain in case the organization's IT team has gotten external domains blocked. You can simply download Flock and invite others in your organization by using their email ids in order to start collaborating. That's all there is in the name of setup.
Pro Free if you don't need the most advanced features
Most of its features are free, even video conferences. But also they have a Pro version with unlimited chat history, Active Directory integration among other things.
Pro Unlimited groups and teams
There is no limit on the number of groups or of group members. Similarly, within a team you can have unlimited members. There is no limit of number of teams too.

Pro Faster than Slack
Flock is offering an app that is faster than Slack.
Pro Highly configurable permissions
For every team, the permissions and restrictions can easily be set over the participating members and the conversations they are having.
Pro Better than slack
Pro Stickers
Posting messages is more fun with them in addition to emojis.
Pro Customisable UI, integrations surface just like native features
There are multiple options like slash commands, message buttons, chat buttons, attachment picker etc., where the integrations can surface inside the native app. This greatly eases the discoverability of a integration, making it really easy for the team members to find and use the integrations.
Pro Free and open source
Rocket.Chat is available for free. It's licensed under the MIT license with source code available on GitHub.
Pro Native apps for all major desktop and mobile platforms
Rocket.Chat has native apps for macOS, Windows, Linux, iOS and Android.
Pro Supports a wide variety of authentication methods
In addition to the usual email / username + password combination, Rocket.Chat supports authenticating via Facebook, Github, Gitlab, Google, Linkedin, Meteor and Twitter accounts.
Pro Understands markdown better than Slack does.
Links work properly, for instance, with square brackets followed by parentheses.
Pro Very active and helpful community
Pro Video conferencing support
Rocket.Chat supports video calls.
Cons
Con No thread feature
Reply command only quotes snippets. There's no implementation to show thread(s) of an initial message.
Con Developer support is non-existent
Can't even create a clean Ubuntu VM with a working developer install. Unresolved dependencies; fails to build. Docs are terrible; actual devs don't respond to questions; error messages are near-opaque. DO NOT RECOMMEND.
Con Web client loses images
In chat rooms with images, before very long, images start to become empty boxes. Useless to pass around visual information
Con No theme customization
Con No chat audit for enterprise
Con Poor security implementations / protocols
Con Centralized
Con iOS app is poorly made
The iOS application is not native, being just a browser container. This means that the UX is quite poor, slow, buttons unresponsive. At this moment they do not provide a decent experience.
Con Android app is poorly made
The Android application is just a badly wrapped web-view which does not perform well and has no form of offline caching whatsoever.
Con Privacy settings are absent
Privacy settings for the server are absent, for instance, you don't have the ability to disable registrations, there's no way to control access to the chat.
Con Features not available out of the box
Con No web browser support
Con Email required for registration
Con No way to block new registrations
Without the ability to disable registrations, there's no way to control access to the chat.
