Databases
The best free resource on SQL indexing I've found. I reread the chapter on partial indexes every few months.
Why count(*) is slow in Postgres and what you can do about it. Saved me from a bad architectural decision.
Streaming replication for SQLite. Makes SQLite viable for production workloads where you'd otherwise reach for Postgres.
Systems & Networking
Consistently the clearest explanations of networking and Linux internals. The zines are great too.
The canonical reference. I have this bookmarked because the local man pages on some distros are outdated.
War stories from production systems. Every post makes me double-check something in my own infrastructure.
Go
Rob Pike's post that finally made Go error handling click for me. Worth rereading once a year.
Opinionated but practical. I don't agree with everything, but it's a solid baseline for team codebases.
Great comparison of stdlib routing vs. chi vs. gorilla. Helped me decide to just use the stdlib in Go 1.22+.
Tools I use daily
Fuzzy finder. I use it for everything: file navigation, git branches, command history, process killing.
Fast grep replacement. The --type flag alone makes it worth switching.
Auto-loads environment variables per directory. Essential for working on multiple projects with different configs.