I see that this thread was posted a month ago but no response on this thread. Hope you’ve found your freelancer but If you’re still looking for a skilled backend developer online, freelance websites are best to look for. Freelancers are listed there as per their skills and are active on daily basis. You can also verify if you’re hiring the right person by viewing their profile and reviews on the platform. Few websites I suggest you to go are:
One of the important benefits of the above freelance platforms is that it is secure to hire freelancers and you will find professionals only who are available and deliver jobs in time.
Hope this helps you with your query.