The Take-Home OA

HubSpot's assessment hands you a live HTTP endpoint. You GET a blob of JSON, you reshape it into an exact output structure, and you POST it back. The endpoint grades you on the spot: a 200 means your answer is correct, a 400 comes back with a note telling you what is still wrong. There is no hidden test harness to reverse-engineer and no trick data structure to recall. The whole game is turning messy real-world records into precisely the shape the spec asks for, and getting every edge case right.

One thing to know before you start. Around mid-2025 HubSpot began routing many candidates to a 90-minute proctored CodeSignal assessment instead of this take-home. The take-home is still honored for people who already sat it, and some reqs still use it, so know it cold. If your invite mentions CodeSignal and a 90-minute timer, read the CodeSignal lesson instead. This lesson is the take-home: the two problems below are the ones candidates report drawing most, and both are shown with their real specs.