He studied computer science at Linköping University where he graduated with a Master of Science degree.
After graduating, Kallstrom worked as a programmer at Framfrab, a Swedish e-consultancy firm. In 200, he travelled to Tokyo where he worked as a freelance graphics and web designer, honing skills and experience that would eventually lead to him starting his own business. Prior to launching his first start-up, he worked as an advisor to Blippex, a search engine that only indexes web pages that have been viewed by real internet users.
In 2006, he founded and served as the Chief Executive Officer of Twingly, a popular blog search engine, before stepping down in 2012 to pursue a new project, Memoto.
He founded the company with Oskar Kalmaru and Bjorn Wesen in Stockholm and started to design and produce the world’s smallest wearable “life-logging” camera, the Narrative clip.