Compare PDFs - Redline & Side-by-Side Deleted in 1 hour

Track-changes-style PDF comparison

Compare two versions of a PDF and download a redline PDF in the format legal and contracts teams expect: deletions in red strikethrough, additions in blue underline. Word-level diff. No watermark.

Three output modes

• Unified redline: single PDF showing the new version with inline strikethrough deletions and underlined additions. Best for sending to a reviewer who wants one document.
• Side-by-side: two-column PDF with v1 on the left and v2 on the right. Best for catching reorganizations.
• Summary report: a clean stats-only PDF showing words added / deleted / unchanged broken down per page. Useful for audit trails.

Color scheme

• Deletions are rendered in red (#cc1f1a) with a strikethrough line.
• Additions are rendered in blue (#1a4fcc) with an underline.
• Unchanged text is rendered in black.

Options

• Ignore whitespace (default on): treats all whitespace runs as equivalent so reflow doesn't show as a diff.
• Ignore case (default off): treats "Hello" and "hello" as the same word.
• Ignore formatting (default on): collapses soft-hyphens and non-breaking spaces before diffing.

Notes & limits

• Free tier: each PDF up to 50 pages. Larger files return HTTP 402.
• The redline PDF re-flows the extracted text rather than overlaying directly on the original PDF, so the layout will not be pixel-identical to v2. Words and ordering are accurate.
• API: POST to /compare-pdf/redline, /compare-pdf/side-by-side, or /compare-pdf/summary with multipart fields file1 and file2.