Here's an article for all developers out there that would like to integrate Sequence into their products and services.
To enable Testnet, simply click on the option right at the bottom of the sign-in page.
One clear indication that you are now on Testnet is a yellow line right below the address bar. When you see this, go ahead and sign-in as normal.
Once you're signed-in, just click on your wallet address to trigger a menu for you to choose the network that you would like to use.
We hope this article helped you. If you have any questions, feel free to start a chat conversation with one of our Sequence Support Agents, or join the discussion on our official Discord channel.