PDF vs DOCX
PDF preserves your layout everywhere and is the right default; DOCX is only better when the employer or agency explicitly asks for an editable file.
The old advice that PDFs break ATS parsing is roughly a decade out of date. Every mainstream system reads text-layer PDFs correctly. What still breaks is a PDF exported as an image — a scan, or a design tool export with text rasterized — because there is no text to extract at all.
DOCX has one real advantage and it isn't parsing: recruitment agencies frequently need to strip your contact details and add their own branding before forwarding you to a client. When an agency asks for Word, they're asking for that, and sending a PDF creates work that sometimes just doesn't get done.
Two mechanical details are worth more than the format debate. Name the file so it's identifiable in a folder of four hundred — Firstname-Lastname-Role.pdf, not resume-final-v3.pdf. And check the exported file's text layer by opening it and selecting the text; if you can't select it, neither can the parser.
Resume parsing
The automated step that converts your uploaded resume file into structured fields — name, roles, dates, skills — inside an employer's hiring system.
Applicant Tracking System (ATS)
The software an employer uses to receive, store, search, and move job applications through their hiring process.