The best alternatives to Just Junior Jobs are BetaList, WorkWithUs, and FirstDevJob. If these 3 options don't work for you, we've listed a few more alternatives below.
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BetaList is a community of makers and early adopters showcasing their startups and exchanging feedback. It provides an overview of upcoming internet startups.
GitRecruit: Start sourcing candidates from Github. Filter candidates based on location, language / skills based follower and RecruitScore which is an aggregate of Github Contributions, Followers, Number of popular projects, stars and a few other metrics.