I'm a hybrid designer/developer, but I socialize with more developers than designers—at conferences, online, etc. I have a very specific form of impostor syndrome. I think it might be instructive when examining impostor syndrome, in the same way that optical illusions can be instructive when examining the workings of perception.
I am not a rockstar designer. Or, for that matter, developer. Or anything, really. I am talented, and I feel that I could be a badass at something. Looking around me at tech conferences and our erstwhile online communities, I think this is a feeling that a lot of us share. We're all looking for that outlet, that thing that we would be a game-changer at doing. In our heads, we fantasize about being some kind of Michael Jordan of X, or maybe something with less glamor. A savant-like rain-man at content marketing, or scalable API design, or documentation, or low-latency concurrent network development, or whatever it is that we think we like doing. The point is that this isn't some humblebrag. I honestly believe that everybody with ambitions to create something of meaning struggles with this, and tech is a community of just such people.
As a designer at developer conferences, I am sometimes treated like some kind of visiting dignitary. Holy shit, you're a designer, but you can talk about Python in complete sentences? Well lookit that. You must be a really badass designer. And we'll forgive your shitty code, because zomg, you're a designer too!
Cross-field impostor syndrome is the worst because I feel like I've pulled a fast one on everybody. They barely have the tools to evaluate this whole other field, and my proficiency therein. I keep waiting for some designer to stand up during one of my talks and say "Um, quite frankly, all of this bullshit is nothing more than your opinion."
What's more, I often feel like I was given the stage by accident. PyCon is a conference full of some astoundingly smart people vying for a tiny amount of speaking slots, so it's a great example. I love watching people get up in front of others and talk about the shit they love. It's a trial by fire; it makes them better. So few are even given the opportunity. I was given that opportunity (twice!) Did I do my opportunity justice? Or did they waste a slot on me simply because I come from foreign fields and make pretty slide decks to illustrate my points?
I know, objectively, that there are not a lot of people who generalize over their career like I do. It doesn't change how I feel. I still look back on my years in open source and I feel unworthy of any kind of praise. I barely write code. I barely maintain my projects. If I deserve recognition in something, it is in talking some talk and getting other people excited enough to make the thing I am imagining. I've basically just self-described as a backseat driver. I hate backseat drivers.
There's no need to reconcile my desire to improve with my impostor syndrome. I've been given some kind of esteem on credit. I'm working to make good on repaying that loan. Moping about it too much won't help me pay down my reputation debt. Actually making things seems like the only viable path to me being not full of shit. Some of the time I succeed at that, and some of the time I get a sliver of credit for doing some critical thinking about how something should be made, without doing the actual work.
Impostor syndrome has a lot of sides. This is mine.