Friday was my last day as a Mozilla employee.

I joined Mozilla almost 16 months ago after spending a decade at Microsoft. I wanted to move into the open source world and no organization represents open source as plainly as Mozilla, the non-profit foundation that brings us Firefox.

Mozilla is filled with wonderful people. I’ll miss many of them but one cool thing about working at Mozilla, and leaving, is that you don’t have to stop being “a Mozillian”.

I joined Mozilla to evangelise the open web. On my first day at Mozilla there were 165 full time employees. Today there are something like 750. Growth that rapid often results in turmoil and Mozilla is experiencing it’s fair share. More importantly to me is that the developer engagement team has shifted it’s focus to primarily drive developer adoption of FirefoxOS.

Don’t get me wrong, FirefoxOS is very cool and it truly amazes me what a relatively small number of engineers have been able to accomplish so far.

To begin with, I’ve discovered that I’m not really the right personality for a non-profit. Every conversation I had with my management left me reminded that I didn’t really fit in.

I wanted to fit in, but my real reason for leaving is that, while I’ve been able to do technically interesting work at Mozilla, the best part of being a technical advisor is being able to help businesses and professionals succeed.

Focusing on FirefoxOS may someday provide that opportunity to Mozilla’s developer evangelists, but not until after it releases, after cell carriers adopt it, after it is released all over the global market and then only if it can successfully compete against Apple, Android, Microsoft and other new players like Ubuntu to succeed where other players (like WebOS) have failed.

I think FirefoxOS has a chance and I wish them well, but at this stage of my career, and given my prior career experiences, I find greater satisfaction in working with larger and more commercial (existing) audiences.

I plan to stay involved with FirefoxOS and especially the Mozilla HTML5 apps initiative, but for full time employment, I’m off to find a better fit.

I made this decision not knowing exactly what I’ll do next.

I know I plan to work on a team, rather than in a group, and that I want role where I can help my company succeed while helping my customer do amazing things !

Stay tuned – I expect to blog in a week or so about my decision !