Depends on the type of internship you are looking for and where you want to work. Most technology companies offer internships, check the company website or reach out to them to find out if they do and how to apply.
The monthly "Who is Hiring" threads are a great resource. A lot of companies have listings for interns. Here's this month's thread for reference: https://news.ycombinator.com/item?id=9996333
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[ 107 ms ] story [ 464 ms ] threadYou can also look here: http://www.internships.com/