Most job applications ask for more than just a resume — a cover letter, references, sometimes a portfolio or work sample — and the portal’s rules about format and file count are usually stricter than they first appear.
Read the listing for two things first: does it specify PDF or Word, and does it want one file or several? PDF is the safer default when it’s not specified, since it keeps your layout intact no matter what device or software opens it. If a system explicitly asks for a .docx (some applicant tracking systems parse Word more reliably) and your only copy is a PDF, see How to Convert a PDF Resume to an Editable Word Document. Watch the extension too, not just the word “Word” — a portal that says “.docx only” will reject an old .doc file, a resume you’ve been carrying forward since an early version of Word being a common case. DOC to DOCX converts it in seconds without changing a word of the content, and DOC vs DOCX explains why portals draw the line there.
If they want separate files, just make sure each one is named clearly — Surname_Resume.pdf, Surname_CoverLetter.pdf — rather than left as Document1.pdf or a scan filename. If they want a single combined PDF, Merge PDF puts your resume, cover letter, and any supporting documents together in the order you choose; the full walkthrough — ordering, converting non-PDF pieces, and the mistakes that get applications flagged as incomplete — is in How to Combine Documents Into One PDF for an Application.
Two things trip up job portals almost every time. The file is over the size limit — portal limits are often tighter than an email attachment limit, sometimes 2 to 5 MB, and Word Document Too Large for a Job Application Portal? covers the fastest fix. Or the layout falls apart after conversion — if your resume came out of a template with columns or graphics, check the result carefully, since How to Convert a PDF Resume to an Editable Word Document covers why layout-heavy resumes are the hardest case for any converter.
Before you submit: open the final file and read it start to finish, since a merged PDF can hide a duplicated page or a missing attachment — View PDF renders every page in the browser without downloading anything, so this takes seconds. Check the file’s title in its properties, not just its filename — see PDF metadata if you’re not sure what’s stored there. And save a version under the exact filename the listing asked for, if it specified one.
Merge PDF or PDF to Word — both free, no email, no account, nothing kept anywhere.