I’ve applied for jobs a few times and this has always been a problem. Now that I’ve been out of college for a while it’s even more of a problem. I don’t have anyone from college that would even remember me. I can’t use my current coworkers because I don’t want my current employer to know I’m leaving until I have a new job lined up. I don’t keep in touch with old coworkers. I don’t do anything outside of work as far as volunteering or anything. I know I’m not supposed to use friends or family. Who is even left after that? The only people I have the contact info for are friends, family, and my current boss.
Piggybacking off this, I wouldn’t just ask a direct manager whether he would vouch for you, I’d also ask for feedback on areas needing improvement too. You don’t have to go into your next job with that same blind spot. Imagine being in a job interview and when they ask you about your “weak areas” you can respond, “I talked with my previous supervisor about this exact issue!” For the last half decade I’ve made a habit of asking for corrective feedback and taking performance reviews seriously. It’s like the opposite of burning a bridge! My current and previous boss are happy to vouch for me!