Each account is believed to be worth six figures and both were previously held by Lewis PR.
Coverity, a ten-year-old firm headquartered in San Francisco, provides software quality testing to brands such as Samsung, NEC and BAE Systems.
As well as continuing Coverity’s ongoing comms with the developer community, Hotwire has been briefed to elevate the company's reputation among senior management by promoting the importance of software and good code to businesses in the UK and Germany.
The account will be led by Hotwire senior programme director Gemma Rowlan, reporting to Coverity’s West Coast-based director of corporate comms Julie Seymour.
New York-based start up MongoDB provides back-end database systems for websites such as eBay, Foursquare and the New York Times and recently closed a $150m (£90m) funding round valuing the company at more than $1bn.
Hotwire will target technology business pages, including enterprise and national business press, to position MongoDB as a challenger brand to firms such as Oracle, initially in the UK and Germany.
The account will be led by Hotwire associate director Kate Hamilton, reporting to MongoDB’s EMEA marketing director Paz Macdonald.