[7] His "Test Tube" project started with the idea of producing a documentary about scientists and their research, but he decided to upload his raw footage to YouTube; from that point "Periodic Videos" and "Sixty Symbols" were developed.

Working with Professor Martyn Poliakoff, Haran's videos explaining chemistry and science for non-technical persons have received positive recognition.

Started in October 2011,[15] Numberphile features videos that explore educational topics from a variety of fields of mathematics.

[citation needed] Haran continues to maintain the Test Tube channel, now titled nottinghamscience, as a place to post extra footage and outtakes from Periodic Videos and Sixty Symbols.

Haran has several channels that have been inactive for several years, which are Words of the World, Backstage Science, Psyfile, PhilosophyFile, Bibledex, FavScientist, and foodskey.

Brady Stuff is Haran's channel for personal videos and is a self-described "dumping ground for clips that don't quite fit anywhere".

In January 2014, Haran launched the podcast Hello Internet along with co-host CGP Grey, another YouTube educational content creator.

[23] The podcast features discussions pertaining to their lives as professional content creators for YouTube, as well as their interests and annoyances.

Typical topics include technology etiquette; movie and TV show reviews; plane accidents; vexillology; futurology; and the differences between Grey's and Haran's personalities and lifestyles.

As a result of their conversations, Haran has been noted for reappropriating the term "freebooting," among other words, to refer to the unauthorised rehosting of online media.

These are usually, but not always, an opportunity for the hosts to attempt to actually create a podcast from an idea previously put forward on the show.

In November 2018, Haran launched The Numberphile Podcast, in which he speaks with various mathematicians in a longer-form version than the YouTube channel.

In January 2023, Haran launched the podcast Younglings with his wife Kylie Pentelow, journalist Amanda Knox, and her husband Christopher Robinson.