While .pdf formats are best at keeping your format in all other situations, .docx formats are most accurately scanned by the ATS. So if you want to beat ATS, a .docx file is suggested. However, always follow directions on the posting!
ATS often convert documents into simple text-only files. Fancy formatting or accessories will be lost or warped – so don’t rely on these features. Use common fonts the software can recognize and scan. If you include any acronyms, also spell them out so that the software will recognize it.
Tailoring your resume with relevant keywords does not mean pasting the entire job description, stuffing it with keywords completely out of context, or adding a section labeled “keywords” where you stick various words from the job description (and more sneakily, in “invisible” white text). You only want to use your keywords if it is truthful and correct to your experiences and skills. Ensure it is still human-friendly.
Some tracking systems only display the URL and drop the words you linked, so it is best to not link any important words (for example, your job title or an accomplishment.) Instead, link words like “website” or “portfolio" or paste the URL without linking it.