[tronko]

There are some startups in Madrid[1], also, apply with LinkedIn and Glassdoor[2] to companies in Spain[3]. Speaking English and somewhat-entendible Spanish you shouldn't have any problem getting and interview. Indeed your English native level can be an asset.

Thus, you should bring to the interviews that have experience working in USA. I think that is pretty valued in Spain.

On the other hand, Madrid seems to have an American expat community, there are some meetups [4][5] and facebook groups, etc.

Don't know about Barcelona.

Good luck!

[1] Take a look at https://www.siliconrepublic.com/start-ups/madrid-spain-start... and https://www.seedtable.com/startups-madrid

[2] https://www.glassdoor.com/Job/jobs.htm?suggestCount=0&sugges...

[3] I know you want to work for a startup but Amazon is in Madrid, maybe you are interested in that?

[4] https://www.meetup.com/es-ES/expats-and-americans-madrid/

[5] https://www.internations.org/madrid-expats/americans

EDIT: formatting.