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AI-powered comparison of two PDFs — additions, deletions, and key differences explained.
Trusted by 10,000+ users · 2M+files processed · SOC 2 compliant
Compare PDF files online with PDFPilot4U — see side-by-side text and visual differences between two PDF versions, with highlighted changes and an exportable diff report. The compare PDFs tool detects added, deleted, and modified text, identifies moved paragraphs, and overlays visual page diffs for image and layout changes. Perfect for redlining contract revisions, tracking edits between document versions, comparing pre- and post-review research drafts, or auditing changes between published and updated specifications. The compare tool uses Claude Sonnet 4.5 for semantic comparison (catches reworded sentences with the same meaning) on top of standard text diffing. Output includes a markup PDF with changes highlighted, a side-by-side HTML report, and a JSON diff for programmatic processing. Free for 3 comparisons per day on guests, 50 on Pro, unlimited on Business.
Drop the original PDF and the revised PDF. The compare tool supports files up to 100 MB each on Pro plans.
Click Compare — analysis completes in 10-30 seconds with text and visual diffs identified.
See changes highlighted in a side-by-side view. Download markup PDF or HTML diff report.
Lawyers compare original and revised contracts to spot every addition, deletion, and clause change before client review.
Researchers compare pre- and post-peer-review drafts to verify all reviewer comments were addressed in the revision.
Engineers compare published vs updated technical specs to identify breaking changes for downstream systems.
How Compare PDFs on PDFPilot4U compares to the most common alternatives.
| Feature | PDFPilot4U | iLovePDF | Smallpdf |
|---|---|---|---|
| Semantic comparison | Claude Sonnet 4.5 | Basic text diff only | Premium only |
| Visual page overlay | Yes — image/layout diff | No | Premium |
| Output formats | PDF markup, HTML, JSON | PDF markup | PDF markup |
| Free daily limit | 30 operations/day (guest), unlimited on Business | ~3 tasks/hour for free, premium starts $7/mo | 2 documents/day free, premium $9/mo |
| Max file size (free) | 5 MB free, 100 MB Pro, 500 MB Business | ~10 MB free | ~5 MB free |
| AI features included | 12 AI tools (Ask PDF, Summarize, Translate, etc.) | Limited — AI add-on only on premium | AI features locked behind premium tier |
| Privacy / data handling | TLS 1.3 + AES-256, auto-delete in 24h, no model training | Files deleted in 2h, standard SSL | Files deleted in 1h, ISO 27001 |
| No watermark on output | Always — free + paid | Free tier may add watermark | Free tier may add watermark |
Standard text diff identifies word-level changes. Semantic comparison (Claude Sonnet 4.5) catches reworded passages with unchanged meaning. Visual overlay detects layout and image differences.
Yes. Scanned PDFs trigger OCR before comparison. Best accuracy from clear scans at 300+ DPI.
Yes. The compare tool detects content language automatically and compares within the same language. Translated versions can be compared semantically.
Markup PDF (changes highlighted inline), side-by-side HTML report, JSON diff for programmatic processing, and PDF summary report.
Yes. Move detection identifies paragraphs that shifted location without text changes — useful for spotting reorganized sections.
5 MB each on guest, 100 MB each on Pro, 500 MB each on Business. Documents with 1000+ pages are supported.
No. Anthropic's API does not train on customer data. Compared PDFs are private and auto-delete in 24 hours.
3 comparisons per day on guest and free accounts. Pro gets 50/day, Business unlimited. No credit card for any tier.
Identifies whether your content was written by AI or a human.
Scans your text and corrects grammatical errors and writing mistakes.
Translates your PDF content into another language while keeping formatting.
Rewrites AI-generated content to sound natural and human.
