Hyrum's Law

ELI5 — The Vibe Check

Hyrum's Law: 'With enough users, every observable behavior of your system will be depended on by somebody.' Error message text, response order, timing quirks — someone builds on them. Change anything, break someone. It's why backward compatibility is so hard.

Real Talk

Hyrum's Law (from Google engineer Hyrum Wright) states that all observable behaviors of a system will eventually be relied upon, regardless of documentation or contracts. This includes undocumented API behaviors, error message formats, performance characteristics, and side effects. It explains why even 'safe' changes can break consumers.

When You'll Hear This

"Hyrum's Law is why we can't fix that misspelled error message — 3 clients parse it." / "Someone depends on our API returning results in insertion order, even though we never guaranteed it."