Finished my Visa onsite last month. Applied for a senior SWE role in the payments platform org at Foster City. Writing this up while it's fresh.
The onsite is virtual (they've kept it that way since COVID and show no signs of changing). It's a full day, split across four or five sessions with breaks in between. Here's the breakdown:
Two coding sessions. Each with a different SWE interviewer. Medium-difficulty problems. My first was an array sliding-window problem with a follow-up asking about space complexity. My second was a variation on graph traversal, basically finding shortest paths with a constraint. Both were clearly pre-set problems, not improvised.
System design. This was the round I was most nervous about and it turned out to be the most collaborative. The prompt was roughly "design a payment processing pipeline that can handle high throughput with idempotency guarantees." Given that this is literally what Visa does, not a surprise. They want you to know: distributed systems basics, queue-based architectures, at-least-once vs exactly-once delivery, failure modes. I got a lot of follow-up on how I'd handle duplicate transactions. Know idempotency inside and out for this company.
Behavioral. Two sessions, different interviewers. Competency-based, STAR format. Questions I got: "tell me about a time you improved the reliability of a system" and "describe a situation where you had to align two teams with different priorities."
Hiring manager chat. Usually at the end. More conversational. Mine asked what I wanted to learn, where I wanted to be in three years, and whether I had questions about the team. This is your chance to show you've done research.
Timeline was actually reasonable: onsite on a Tuesday, recruiter feedback call the following Monday. I've waited three weeks at other companies.
One note: the interviewers are generally thoughtful and will give you a hint if you're stuck for a while. Don't stare at the screen in silence. Just narrate what you're thinking.