I migrated 12 client projects off Heroku. Here's the playbook (and the 7 things that bit me every single time).

Disclosure: I'm a senior backend tech lead and I run HostingGuru. Six of these 12 migrations landed on HostingGuru. The other six went to Render, Railway, Fly.io, or back to a VPS. The playbook below works regardless of destination — it's the Heroku-side problems I want you to skip. Since Heroku announced "sustaining engineering mode" in February 2026, I've been the person clients call when they need to get off the platform without breaking production. As of this week I've done 12 migrations — R