I got error reports from both Chrome and Firefox when attempting to log into Tatoeba just now.

Firefox reports:
Your connection is not secure. The owner of tatoeba.org has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website. tatoeba.org uses an invalid security certificate. The certificate expired on 2016-aŭgusto-13 16:12. The current time is 2016-aŭgusto-13 20:18. Error code: SEC_ERROR_EXPIRED_CERTIFICATE

Chrome reports: Your connection is not private. Attackers might be trying to steal your information from tatoeba.org (for example, passwords, messages, or credit cards). NET::ERR_CERT_DATE_INVALID. tatoeba.org normally uses encryption to protect your information. When Google Chrome tried to connect to tatoeba.org this time, the website sent back unusual and incorrect credentials. This may happen when an attacker is trying to pretend to be tatoeba.org, or a Wi-Fi sign-in screen has interrupted the connection. Your information is still secure because Google Chrome stopped the connection before any data was exchanged.
You cannot visit tatoeba.org right now because the website uses HSTS. Network errors and attacks are usually temporary, so this page will probably work later.