Check a file type before opening it

Use this when

• Use this workflow when the task matches the intent in the title: check a file type before opening it.
• Use this workflow when a downloaded file has an unfamiliar extension, came from a shared archive, or needs a quick local sanity check before you open it in another app.
• Use it when the PDF itself needs work: page order, size, metadata, hidden signals, text, images, form state, print layout, or final sharing quality.
• Use it before sending a PDF outside your workflow, especially when the file came from another app, person, scanner, or converter.
• Use it when the task crosses 3 tool families and the result needs to move cleanly from one format or context into another.

Avoid this when

• Avoid starting with final-copy operations like compression, watermarking, or page numbering before page structure is correct.
• Avoid assuming PDF inspection is malware scanning or legal review; it is a practical signal layer for document workflow decisions.
• Avoid OCR expectations unless the guide or tool explicitly says OCR is part of the path.
• Avoid skipping the review step just because the tools are browser-local or instant.
• Avoid using the workflow as a replacement for source-of-truth review when legal, medical, financial, academic, or regulated decisions are involved.

You are done when

• Page count, order, rotation, metadata, file size, and visible output match the intended destination.
• Any hidden PDF signals discovered by inspectors have been intentionally accepted, cleaned, or routed into another workflow.
• The final PDF copy has been kept separate from the original source file.
• The result has been opened, reviewed, and checked against the real destination requirement rather than only against the page preview.
• The next action is clear: download, copy, verify, compress, convert, compare, archive, or continue into the linked workflow.

Sequence

PDF workflows should inspect and organize first, transform second, and verify last because later operations can hide or compound earlier document problems. This guide starts with “Check the visible file against the detected type” and ends with “Verify the final file when identity matters” so the user does not jump straight to a final output before the input and review conditions are understood.