https://www.cnet.com/news/heads-up-nintendo-switch-online-multiplayer-costs-money-starting-today/

The online multiplayer experience on Nintendo Switch is about to change: later today, the company is set to launch Nintendo Switch Online. The paid online service will cost $3.99 a month or $19.99 a year -- and will be required for Switch owners who want to play multiplayer games over the internet. In other words, the service is effectively putting parts of major titles like Splatoon 2 and Mario Kart 8 behind a paywall.

If you're not willing to pay for online play, however, you've still got a few hours to squeeze in a few rounds: The company stated on Twitter that its online services would be undergoing maintenance at 5pm PT in preparation for an evening launch.