: Using older, unsupported software like version 9 poses security risks, as it does not receive patches for modern vulnerabilities.

: Be extremely cautious of third-party sites offering "Nitro Pro 9 Full Version Free." These are often cracked versions that may contain malware or viruses. 2. How to Use Nitro Pro for Free Legally

: A lightweight Windows tool that offers extensive features for free, though some advanced tools will add a watermark to the saved file.

: Nitro Pro 9 reached its "sunset" period years ago. The official developer, Nitro Software , no longer provides download links or technical support for this version.

: A highly recommended, truly free desktop app (Windows/Mac) that includes editing, merging, and even OCR without watermarks.

If you need a permanent free solution for editing PDFs, several modern tools offer features similar to Nitro Pro without the subscription cost:

: After 14 days, the advanced features (editing, OCR, converting) will lock, but you can often still use it as a basic PDF viewer. 3. Best "Truly Free" Alternatives