[citation needed] Ad Fontes Media has its origins in a blog called All Generalizations are False which was written by patent attorney Vanessa Otero from Denver, Colorado.

"[5] In 2018, Ad Fontes successfully launched a crowdfunding campaign to improve the technology behind the chart, increase the number of analysts, and make the site's methodology more transparent.

[10] During the September 2020 media bias project, nearly 1800 individual articles and TV news shows were rated by at least three analysts with different political views (left, right and center).

Analysts are selected by a panel of application reviewers consulting a rubric of candidate qualifications—including education, political/civic engagement, familiarity with news sources and United States government systems, reading comprehension and analytical skills, among others (Otero, 2021).

Once hired, analysts complete a minimum of 20 training hours to learn the content analysis procedure before contributing ratings to the data set (Otero, 2021).

'"[14] In 2018, a Columbia Journalism Review article questioned the thoroughness of the Media Bias Chart (when it was based solely on Otero's opinions) and similar initiatives, stating that "the five to 20 stories typically judged on these sites represent but a drop of mainstream news outlets' production".