Advent and Holiday Calendars 2020

Here are some advent and holiday calendars for 2020:

Web Performance Calendar – The speed geek’s favorite time of the year

Advent of Code 2020

Perl Advent Calendar 2020

Lean UXmas 2020 – The top articles from 2020’s Agile & Lean UX News

24 Days in December – Thoughts of the PHPamily

There is one in French:

24 jours de web : Le calendrier de l'avent des gens qui font le web d'après