I am in the process of applying to some tech companies for the next summer (contact me if you have an open position hehe). Here are some things I experienced and also some tips for the ones also applying.
From Germany I was used to a very easy-going process. Companies highly valued credentials (degrees, courses taken, references, ...) for the technical skills. Interviews were then focused on soft skills and assessing at which team/project I could apply my strength best. Interviews were always directly with a representative from the team/group I was applying to. Soft skills would be assessed through team exercises (not technical) in so-called "assessment centers", role plays, experience questions (like"can you tell me about a situation where it was difficult to work with other people?") and other questions like "what do you think is important for good time management?". Then, for the rest of the interview they would explain different projects they are hiring for and try to see how I could fit into them. The whole process would usually only involve an initial phone call to discuss logistics and then one on-site interview. Most German companies value etiquette highly. Your writing better be flawless and the cover letter is probably the most important part of the application. It is really important to make a good point about why this company excites you.
My experience in the U.S. is very different. The initial contact is very focused on the "résumé". Recruiters at job fairs will sometimes just ask you for your résumé and that's it. Students will sometimes come to tech talks just to give their résumé to the recruiter and won't even stay for the talk. Also there are companies whose entire application process just consists of uploading a résumé. So are applications in the US very credential based? I can't say either, because most companies haven't even asked me for transcripts or reference letters. And many emphasize that they recruit people with all sorts of education paths. Weird. Instead, I would say that recruiting is less credential based than in Germany, because the U.S. companies all want to assess technical skills themselves through a series of technical phone interviews. And only if you pass through them you get an onsite interview. I honestly have my doubts on how good this process is as the sample size the company gets from two or three 45 minute technical phone interviews is rather small. Further, at some companies the interviews are with random software engineers in the company, who don't know about you, and have little incentive to make a good phone interview. But maybe degrees from U.S. universities don't say much, many applicants went through a different education or many applicants are from foreign countries with uncertainty about the significance of their degrees.
Anyways. To be successful, one needs to specifically prepare for this kind of interview. I recommend skimming the book Cracking the Coding Interview to get gist of why companies think they do these interviews, what they are looking for, what to expect, as well as some general strategies for answering questions. The book also contains sufficient review material to quickly freshen up your basic programming skills if needed. Then there is also a section of typical interview problems. But there are websites that provide the same and also let you write and test the code on the website directly. I can recommend CodeLab and LeetCode. Topcoder is another site that many recommend, but it's much more blown up. The book, on the other hand has very good solutions to the problems and also a good system of giving you hints if you're stuck. But don't be fooled. The interview questions I was asked in the actual interviews were sometimes much tougher than the ones in the book or online.
Another recommendation I have is Triplebyte (a Y Combinator company). The concept is that you do the first round of technical interviews with them (first online and then over the phone). If you are successful, you can then directly go to the onsite interviews of their partners. And they have a lot of very interesting partner companies. They save you a lot of stress. Otherwise you would have pretty much the same interview round with all the companies you apply for. That's not only cost for you, it's also cost for the companies. So by saving this cost, Triplebyte is able to invest more into optimizing their interview process. They also have a nice philosophy: Very data-driven, they don't look at credentials at all, and they focus on the applicants strength instead of weaknesses. So I highly recommend checking them out if you are applying for interviews/jobs in the space: Triplebyte.