Tumbler

Recommendation

https://www.tumblr.com/docs/en/custom_themes

ab 2018

https://github.com/tumblr/docs/blob/master/npf-spec.md

If the original dimensions of the media are not known, a boolean flag original_dimensions_missing with a value of true will also be included in the media object. In this scenario,** width and height will be assigned default dimensional values of 540 and 405 respectively**.