HumanPen is a document-level AI polish tool: import a Turnitin or iThenticate AI detection report (or pick paragraphs yourself), rewrite only the flagged sections, and keep layout, citations, formulas, numbers, and meaning as intact as possible. You are billed for words actually rewritten—not for the whole draft. If a recheck still shows ≥20% on remaining flagged spans, those spans can be re-run at no extra charge until the report is under 20% (product wording, not a promise that any school or detector will pass). Start at https://humanpen.net.