Mind mapping is a brainstorming technique where visual diagrams are used to show how thoughts or ideas are connected.
The process is commonly used in project planning and presentations. In today’s digitally-focused world, it’s easier to create and share mind maps than ever before. Here are a few cloud-based applications that let you and your team create and modify a mind map together.

Bubbl.us

Bubbl.us is a free tool that allows you to create online “trees” in order to brainstorm and map ideas. Start with a central topic, then add new topics either at the same level or one level lower. Bubbl.us will format these bubbles into a tree automatically, though you can also move the bubbles around to suit your needs. You can also change the color and size of your bubbles to bring style to your brainstorming session. Bubbl.us is free, but an account is required in order to create or edit a tree.

Link - https://bubbl.us/

SpiderScribe

SpiderScribe is an online-based brainstorming and mind mapping tool that allows you to easily share your mind map with others. You can use SpiderScribe to connect files, notes and even calendar events on maps you can design how you want. Your maps are stored in the cloud, which means that you and the people you choose to share the map with can access and edit it at any time. SpiderScribe offers a free personal account and offer upgraded “pro” and “business” options for a small fee.

Link - https://www.spiderscribe.net/

Popplet

Popplet is a versatile mind mapping tool that allows multiple users to work on the same project. Popplet allows users to add media such as images or video to their maps. Maps can also have tags or categories applied to them, which makes them easy to sort through later. Popplet can be used both on PC and iOS compatible devices, though no Android version is currently available.

Link - https://popplet.com/

Coggle

Coggle is a free and easy mind mapping application that you can sign in to via your Google account. When creating a mind map with their software, Coggle will automatically randomize the color of each branch, although you may change it to whatever color you wish by clicking on the branch you want to change.

When you have completed your mind map, you can download and share it with your friends or co-workers. Not only that, but you may allow the people that you share your mind map with to edit the content too. It also gives you the option to look at what your mind map looked like before you allowed other people to make changes on it.   

Link - https://coggle.it/

GroupMap

GroupMap is all about making team-based activities easier. You can create or select a map, then invite a team to comment, collaborate and even vote on the best ideas. Everyone gets to add their views to the brainstorming session and GroupMap collects these ideas and displays them all in a group view for comment and for voting. GroupMap is easy to use, offers a free account option, and gives every member of the team a voice when it comes to collaborating.

Link - http://www.groupmap.com/

These are just a few of the mind mapping tools available online.
There are many other services available offering mind mapping resources and other useful brainstorming tools.
It’s up to you to decide which is best to help you and your team organize your ideas.