I used to maintain locally a clumsy spreadsheet -- now I'm using this, directly hosted on my website. I only list conferences I consider participating in (submitting papers, attend, and/or contribute as a member of program committees).

To add or update a deadline:

• Update _data/conferences.yml
• Make sure it has the title, year, id, link, deadline, timezone, date, place, sub attributes
  • See available timezone strings here.
• Optionally add a note and abstract_deadline in case the conference has a separate mandatory abstract deadline

This is a fork from the excellent ai-deadlines.