I use Google Calendar as my todo list. Syncs across devices. Notifications. Share with Family & Work. Repeating tasks. Supports notes and attachments. Multiple Lists (calendars). Free.
>Firefox blocked this page because it may trick you into doing something dangerous like installing software or revealing personal information like passwords or credit cards.
No no, I assume it's because it impersonates Hacker News, a popular website. The Details even says this: it thinks you are trying to phish for hackernews sign ins.