Windows Search (File Explorer)
Windows can search inside the content of your PDFs right from File Explorer, but only if the folder sits in the indexed locations and the PDF file type has content indexing turned on. Setting it up is free; rebuilding the index can take hours.
Steps
- Open Indexing Options (type it in the Start menu).
- Click Modify and check that the folder where your PDFs live is among the included locations. If you keep everything on an external drive or a network folder, it probably isn't, and that's why it "finds nothing".
- Click Advanced → File Types, find the pdf extension, and check "Index Properties and File Contents".
- If you just changed something, use Rebuild under Advanced → Index Settings. Honest warning: the rebuild can take several hours, or a full day with many files.
- Then, in Explorer, go to the folder and search. To force a content search you can type content: "what you're looking for" in the search box.
Real limits
- It only searches where the index reaches. Network folders, external drives, and freshly added folders tend to stay out until you include them and wait for indexing.
- It searches for words, not ideas: if the document says "lease" and you search "rent", there's no result.
- It tells you which file has the word, but not on which page or in what context: you still have to open the PDF and repeat the search inside.
- And the limit they all share: if the PDF is a scanned image, there's no text to index. We come back to this below, because it's the typical case.