Is it hold onto or hold on to?
It’s “hold on to,” because “hold on to” is a phrasal verb. It means “to keep something” (e.g., “I held on to his letters”) or “to grip tightly” (e.g., “Hold on to the rope!”).
Choosing onto or on to can be confusing. “Onto” is a preposition that means “on top of” or “upon” and must be used with verbs that express movement (e.g., “Climb onto the rock”).
To make sure you use these words correctly, use QuillBot’s free Grammar Checker.