By default Matomo (Piwik) provides five Custom Dimensions slots. You may configure Matomo to track more Custom Dimensions. New Custom Dimension slots will be created in both the ‘visit’ scope and ‘action’ scope.
First you need to be able to connect to the server running Matomo over SSH, so you can type commands to the Matomo console. To add 10 new Custom Dimensions slots from 5 to 15, type in the terminal:
$ cd /path/to/piwik $ ./console customdimensions:add-custom-dimension --scope=visit --count=10
You can now track up to 15 custom dimensions in the visit scope. Enjoy!
You can create at least 50 dimensions in each scope (100 in total), and possibly even a few more (there is usually a hard limit from the database which will be hit when you create between 100 and 200 dimensions).
This console command
customdimensions:add-custom-dimension updates your Matomo Database schema and adds new columns in several tables in order to track more custom dimensions.