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Vercel’s developer experience is genuinely excellent — push to Git, get a URL, previews for every pull request. The bill is the problem: per-seat pricing plus usage, and it scales with your success. Dokploy is the self-hosted answer that’s been eating that market: an open-source PaaS that gives you the same workflow — Git deploys, automatic HTTPS, preview environments, one-click databases — on a VPS you control, installed with a single command. Here’s the full setup, including the parts the highlight reels skip. ...

Google “Spring Boot JWT tutorial” and the top results still hand you the 2019 recipe: a custom OncePerRequestFilter that parses the Authorization header by hand, a third-party JWT library, a UserDetailsService, and five config classes of glue. It works — the way a hand-rolled ORM works. On Spring Boot 4, Spring Security 7 has first-class JWT support through the built-in OAuth2 Resource Server. No custom filter. No third-party JWT library. Here’s the modern shape, including what Security 7 removed out from under the old tutorials. ...

Every Spring codebase has its own API versioning story, and they’re all slightly embarrassing: /v1 and /v2 prefixes baked into paths, a custom header parsed by hand in an interceptor, or two parallel controller classes that drift out of sync. Spring Framework 7 — the foundation of Spring Boot 4 — finally makes versioning a first-class citizen: a version attribute on @RequestMapping and every shortcut variant, with the framework handling resolution, matching, and deprecation. Here’s how to use it, and where it bites. ...

Migrating one service to Spring Boot 4 is a weekend project. Migrating sixty is a program — and programs fail in a specific way: every team independently rediscovers the same seven errors, burns a week each, and the “migration” becomes sixty snowflake upgrades with sixty subtly different outcomes. The fix is a discipline with an unfriendly name and a friendly result: solve every error once. When a team hits a migration error, the output isn’t a fixed service — it’s a permanent, automated fix that no other team ever has to think about again. Here’s the playbook. ...

“Detect a cycle in a linked list.” Everyone recites it: slow moves one step, fast moves two, if they meet there’s a cycle. Then the interviewer says “why can’t fast skip over slow?” and the room goes quiet. Then “find where the cycle starts” — and the memorized answer runs out. Floyd’s tortoise and hare is a two-minute algorithm with a twenty-minute understanding. Here’s the understanding. The shallow answer (and why interviewers hate it) The HashSet version works and every candidate knows it: ...