Okay, so I applied to Vercel as a new grad last semester and made it to the final onsite before getting passed on. I wanted to post this because there's a lot of content about Vercel interviews for senior SWE and basically nothing for someone coming in at the entry level.
First thing to know: Vercel does not have a formal new grad program like some big tech companies. You're applying to a specific team's opening and you'll be treated somewhat like a junior hire, not a rotational program. That means the bar for technical depth is real even at the junior level.
What the loop looked like for me:
Recruiter screen, then a 45-minute technical screen with a mid-level SWE on the team. That was one algorithm problem (medium difficulty, tree traversal variant) and discussion of a past project. Nothing about Next.js or Vercel-specific tooling in this round.
Onsite was three rounds: another coding round (two mediums, similar difficulty to Leetcode), a system design "lite" (design a simple URL shortener, nothing distributed-systems scary), and a behavioral round focused on curiosity and motivation.
For prep: Solid grounding in DS&A at the Leetcode medium level is the floor. You don't need to have solved 500 problems, but you need to be fluent explaining your approach. The system design was genuinely lite for an entry-level candidate. They're not expecting a distributed cache design. Think: basic components, basic tradeoffs, can you reason about scale. The behavioral felt important. They asked a lot about projects I'd built and why I made certain decisions. Have one or two things you can talk about with real depth.
I think I didn't get the offer because I fumbled the behavioral round. I was so focused on the coding prep that I hadn't really articulated why I wanted Vercel specifically versus just "cool devtools company". They seemed to care that you actually use their products or at least understand the developer experience space.
FWIW if I interview there again I'd spend way more time on that piece. The coding bar is not unreasonable for a new grad who's put in reasonable prep.