Well gulp.de is the main one, they are also an agency of sorts (I've worked for them a couple of times) and the paid service is worth it. Jobserve is also in German, then there is IT Jobs: Feste und befristete IT-Stellenangebote bei IT Job Board who have been sending em a lot of stuff recently, and of course there's IT Projektbörse - computerwoche.de but Google is probably your best bet for finding the websites as there are, literally, dozens of them

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