The Matter web app is designed and tested for modern browsers. Inside Slack and Microsoft Teams, Matter runs in the Slack or Teams app itself, so this only applies to the web app at app.matterapp.com.
Supported browsers
The current version and one version back of each of these, on desktop and mobile:
Google Chrome
Apple Safari
Mozilla Firefox
Microsoft Edge
Internet Explorer is not supported.
Seeing a "Please update your browser" page?
Your browser is out of date or not on the list above. Update it, or switch to Chrome, Firefox or Edge. If you still have trouble on a supported browser, email support@matterapp.com with your browser name and version.