Repair & Optimize PDF Online (Free, Private, No Upload)

Fix corrupted, damaged, or broken PDF files and optimize PDF structure for improved performance, all entirely within your browser without uploading sensitive documents to external servers. This tool diagnoses PDF issues, repairs structural problems, removes errors, and optimizes file organization to create cleaner, faster-loading documents. PDFs can become corrupted through incomplete downloads, failed email transfers, sudden application crashes during saving, hard drive errors, or software bugs during PDF creation. Symptoms of corrupted PDFs include files that won't open in PDF readers, documents missing pages or showing blank pages, error messages about invalid PDF structure, extremely slow loading times, or crashes when attempting to open the file. The repair tool attempts to reconstruct damaged PDF structure, recover readable pages from partially corrupted files, remove invalid objects and references causing errors, rebuild the cross-reference table that indexes PDF contents, and optimize internal organization for faster access. Beyond repair, the optimization features improve healthy PDFs by removing unused objects and resources, compressing content streams more efficiently, and reorganizing file structure for faster web viewing. This is valuable for rescuing important documents from corruption when no backup exists, recovering data from PDFs damaged during transmission, optimizing large PDFs for faster loading in browsers and viewers, cleaning up PDFs created by buggy software, and preparing documents for long-term archival. The tool works entirely locally in your browser, ensuring that sensitive business contracts, confidential reports, personal documents, or proprietary information never leave your device—critical when dealing with already compromised files where security is paramount. Use this for corporate documents that won't open after download, scanned documents exhibiting errors, PDFs created by legacy software showing compatibility issues, and any PDF where you're seeing error messages or unexpected behavior.

How to Repair and Optimize a PDF

  1. Click Choose PDF and select the corrupted or problem PDF.
  2. Wait for the diagnostic scan to complete. The tool will:
    • Check PDF validity and structure
    • Identify errors and warnings
    • Suggest applicable repairs and optimizations
  3. Review the diagnostic results showing detected issues.
  4. Select optimization options (recommended defaults are pre-checked):
    • Rebuild PDF Structure: Reconstruct from scratch to fix issues
    • Remove Unused Objects: Delete orphaned resources
    • Optimize Content Streams: Compress page content
    • Linearize for Web: Enable faster browser loading
  5. Click Repair & Optimize to process your PDF.
  6. Download the repaired and optimized version.

Related tools: Compress PDF, Convert to Grayscale, Merge PDFs

FAQ

Can this tool recover content from severely corrupted PDFs?

The repair tool can fix many types of corruption, particularly structural issues like broken references, invalid objects, or incomplete cross-reference tables. However, if the actual page content data is corrupted or missing, recovery may not be possible. The diagnostic scan will show whether the PDF has recoverable pages. For severely damaged files, the tool attempts to extract whatever content remains readable.

Will repair change the content or appearance of my PDF?

No, repair aims to preserve all original content and appearance while fixing structural issues. Text, images, formatting, and layout should remain identical. The tool rebuilds the PDF's internal structure without altering the actual page content. If you notice any differences, it means those elements were corrupted in the original and have been reconstructed as closely as possible.

What's the difference between repair and optimization?

Repair fixes errors and corruption that prevent the PDF from working correctly. Optimization improves performance and file size for PDFs that already work fine. You can use both together: repair structural issues while also optimizing for better performance. Even healthy PDFs benefit from optimization to load faster and use less storage.

Can this fix password-protected or encrypted PDFs?

No, encrypted or password-protected PDFs cannot be repaired or optimized without first removing the protection. The tool will detect encryption and notify you. Use the Unlock PDF tool first if you know the password, then repair/optimize the unlocked version.

How does this compare to professional PDF repair software?

This tool handles common PDF corruption and optimization tasks well, particularly for moderately damaged files with structural issues. Professional desktop software may have more advanced recovery algorithms for severely corrupted files with damaged page content. However, this tool offers key advantages: it's free, works instantly in your browser, keeps your files completely private (no upload), and handles the majority of PDF issues effectively.

Will optimization reduce file size?

Optimization can reduce file size, sometimes significantly, by removing unused objects and compressing content streams. However, the amount of reduction varies. PDFs created by efficient software may see little change, while PDFs with lots of orphaned objects or uncompressed streams may shrink considerably. For maximum size reduction, use this tool in combination with the Compress PDF tool.

What should I do if the repair doesn't work?

If the tool cannot repair your PDF, the corruption may be too severe for automated repair. Try these alternatives: (1) Return to the original source and re-download or request a fresh copy. (2) If the PDF was created from another format, recreate it from the source document. (3) Try opening in different PDF readers—sometimes one reader can open files that others cannot. (4) For irreplaceable documents, consider professional data recovery services that specialize in PDF repair.