She subsequently joined a United Kingdom-based startup that built product management software, where she was solely responsible for the company's direct marketing.

[1] Soon after the 2016 United States presidential election, Jammi visited the Breitbart News website and saw an Old Navy ad with a photograph of an interracial couple.

[2] She and Matt Rivitz, a copywriter who had just pushed for mortgage company SoFi to stop running ads on Breitbart, joined together to create the initially anonymous Sleeping Giants campaign in November 2016.

[2][6] Sleeping Giants also engaged in campaigns to pressure advertiser boycotts of other websites and individuals, including Tucker Carlson and Bill O'Reilly.

[2] Jammi joined marketer Claire Atkin to continue her activism and research around advertising's enablement of publishers of fake news, far-right content, medical misinformation, and conspiracy theories.

[9] Through their work with Check My Ads, Jammi and Atkin have reported on broad keyword blocklisting of words like "coronavirus", "racism", and "immigration", a practice they say has been detrimental to the news industry as a whole.

[14][15] Jammi is on the advisory committee of Good Information Inc., a public-benefit corporation launched in October 2021 and led by Tara McGowan.