Your security certificate has expired
Using Chrome, Todoist is showing as being 'offline' (hence I cannot sync using https).
When I tried to open a new session, I was greeted with:
The site's security certificate has expired!
You attempted to reach todoist.com, but the server presented an expired certificate. No information is available to indicate whether that certificate has been compromised since its expiration. This means Google Chrome cannot guarantee that you are communicating with todoist.com and not an attacker. Your computer's clock is currently set to Wednesday, October 16, 2013 3:51:38 AM. Does that look right? If not, you should correct the error and refresh this page.
You should not proceed, especially if you have never seen this warning before for this site.
Proceeding anyway, my address bar shows https with a slash through it!