Every interviewer is a node in a network you don't currently have access to. Even when a role doesn't work out — wrong level, wrong timing, they went with an internal candidate — the person you spoke with still knows other people hiring for adjacent roles. Almost nobody asks for that. It's one of the highest-leverage, most underused moves in a job search.
Why this works better than it feels like it should
People are generally more willing to make a low-effort introduction than to advocate hard for a stranger. A referral costs the interviewer almost nothing — a two-line email connecting two people — but for you, it converts a cold application into a warm one, which typically responds at a much higher rate. You already did the hard part: they met you, formed an impression, and (if the interview went reasonably well) have a positive one.
When to ask
Not during the interview itself, and not if you're still in an active process for that exact role — asking for referrals elsewhere mid-process can read as hedging. The right moment is after you've gotten a clear no, or after you've accepted a different offer and the process has naturally closed. At that point the ask is low-stakes for both of you.
How to ask, without it feeling transactional
The version that works is specific and low-effort for them to act on — not "know of anything open?" which puts the thinking burden on them.
Notice what that does: it's specific enough to be actionable ("this type of role, this type of company"), it doesn't demand anything, and it leaves the relationship open rather than treating it as a closed transaction.
Following through on your side
If someone does refer you, close the loop — tell them how it went, thank them regardless of outcome, and look for a chance to return the favor later. Referral relationships that go one direction stop happening. The ones that compound over a career go both ways.
Where this fits into tracking your search
This only works if you actually remember who you talked to and what was discussed — six months later, "the person from the Series B fintech interview" is not retrievable from memory alone. Keeping every interviewer as a contact, tagged to the role and with a note on how the conversation went, is what makes the referral ask possible at all when the right moment comes.