PDF security
What does Compare PDF do?
Compare PDF opens exactly two PDFs side by side in the browser. Text comparison lists additions, deletions and replacements; content overlay reveals image and layout differences with adjustable opacity and sensitivity. Search the change list and select a result to locate its page. Independent zoom, a hand tool and synchronized scrolling help you review both versions. Download a PDF report containing marked reference pages and the complete change list.
How to use Compare PDF
- 1Add exactly two PDFs
Open Compare PDF and select two files: the reference and the changed copy. Unlock either file first if a password is required.
- 2Choose a comparison mode
Text comparison finds edits in extractable text. Content overlay compares rendered pages, with balanced, strict or relaxed sensitivity for smaller visual differences or raster noise.
- 3Inspect changes locally
Search the change list, click a change to jump to its page, and use zoom or synchronized scrolling to inspect both versions. In overlay mode, adjust opacity to reveal either document.
- 4Read the marks, then review the sources
Download the report and inspect every marked region. Confirm legal or accessibility impact in the original files, not from the overlay alone.
Supported files and limits
- Output format: PDF comparison report
- Input: PDF
- Output options: text comparison and content overlay; balanced, strict or relaxed sensitivity
- exactly two PDFs per task; text comparison requires extractable text; scans use content overlay
- Files stay on this device and are removed when you close the page.
Exactly two PDFs are required per task. Pages are paired by page number. Text comparison requires extractable text; use content overlay for scans. It does not provide a semantic, accessibility or legal reading of changes.
What the output keeps
- rendered reference pages
- visible difference marks
Rendered reference pages and visible difference marks are retained in the report.
What may change or be lost
- semantic meaning of changes
- accessibility and legal interpretation
Semantic meaning of changes, accessibility consequences and legal interpretation are not produced. Layout-only noise can still be marked depending on sensitivity.
When not to use this tool
Do not use Compare PDF as a contract redline, as proof that two files are legally equivalent, or as a substitute for reading both PDFs. It also cannot compare a PDF with a Word file in one step.
If processing fails
If you add fewer or more than two PDFs, the task is rejected. Encrypted files must be unlocked first. Very large page sizes can exhaust memory; compare extracts if needed. A report with no marks still does not prove legal sameness.
Privacy boundary
Both PDFs are compared in this browser. They are not uploaded to a PDF Smart Kit application server. Close the page to clear the pair from memory.
Testing evidence
Last tested: · Test browser: Chromium · Product version: 1.0.0
Sample: Two PDF versions containing text, graphics and an added page · 3 pages
What was checked
- Text replacements and an added page are detected.
- Visual differences on image-only pages are detected.
- The download is a valid PDF.
Known failures and limits
- The report is visual and does not provide legal interpretation.