The stage where the job stops being “complete the ticket” and starts being “decide how the ticket should have been written.”
A mid-level engineer typically has three to five years of experience, has moved past learning basic fluency in their core languages and frameworks, and starts owning meaningfully sized pieces of a project rather than just executing tasks handed down from someone else. It’s also, per the essay this term appears alongside, the tier of “routine work” most exposed to near-term AI automation — mid-level output is often precisely the kind of well-specified, pattern-following work current coding assistants are best at replicating.
Same honesty note as Junior Developer: an informal industry convention, not an academically defined or certified category.