When Jimmy Rosén first started working with the web, it was in the days of early Content Management Systems. As he learned more about the importance of the open web and web standards, he became increasingly annoyed at the terrible, non-standards-compliant code these programs produced.
Over the course of years, the fact that these tools were both proprietary and producing awful code for his clients made him angry. So when he was ready to start an agency that valued open source and open web standards, he called it Angry. Not because we are angry, but to remember our genesis and purpose. To remind us that the open web is something we have to value, contribute to and defend, not something we can take for granted.
Oh, and the Creative part? All Swedish digital agencies were called [Something] Creative (or a similar buzzword) back then.
So there you have it. Angry Creative.