Will text still be searchable after compression?

No. This tool converts each PDF page to a JPEG image and rebuilds the PDF from those images. After compression, text is no longer selectable or searchable. This is a known limitation of browser-based PDF compression.

Why is the compressed file larger than expected for text PDFs?

Text-based PDFs store text as vectors, which are very compact. Converting them to rasterized images at any DPI typically increases the file size compared to the original. This tool is most effective for scanned or image-heavy PDFs.

How does parallel processing work?

Parallel processing uses Web Workers to render multiple PDF pages simultaneously instead of sequentially. For multi-page PDFs, this can provide 3-5x speed improvements. The feature is automatically enabled for PDFs with more than 2 pages when the Parallel Processing checkbox is checked.

What is target file size mode?

Target file size mode lets you specify a maximum file size (e.g., 5MB). The tool samples the first page, then uses binary search to find the optimal JPEG quality that will produce a file at or below your target size. This is useful when you need to meet strict upload limits.

Can I compress multiple PDFs at once?

Yes. Upload multiple PDF files and the tool will process them sequentially, showing per-file progress. Results are packaged into a ZIP file for download. Each file is compressed using the same settings.

Is there a page limit?

There is no hard page limit, but large PDFs with many pages may take several minutes to process. With parallel processing enabled, multi-page PDFs compress significantly faster. Use the page range option to process large documents in sections.

What if the compressed file is larger than the original?

The tool automatically returns the original file if compression produces a larger result. This can happen with text-heavy PDFs or PDFs that are already highly optimized.

Can I compress password-protected PDFs?

Yes. If your PDF is encrypted with a password, enter the password in the password field before compressing. The tool will use the password to unlock the PDF for processing. The password is never stored or transmitted.

How accurate is the estimated compressed size?

The estimated size is calculated by sampling the first page and extrapolating based on the total page count. It's a rough estimate (typically within 10-20% of the actual result) that helps you decide whether compression is worthwhile before committing to the full process.

What does Auto mode do?

Auto mode analyzes the first page of your PDF to determine if it's text-heavy or image-heavy. It then automatically selects the optimal preset: High Quality for text-heavy documents (to preserve readability), Screen for image-heavy documents (maximum compression), or eBook for mixed content.

Does metadata preservation affect file size?

No. Metadata preservation only copies the title, author, and subject fields from the original PDF to the compressed version. This information takes up negligible space (a few bytes) and doesn't impact compression ratios.

Compression

PDF Compressor Online Free

Compress PDF files by re-rendering each page to a compressed image and rebuilding the PDF. Features parallel processing for multi-page PDFs, target file size mode, batch processing with ZIP download, and side-by-side original vs compressed comparison. Choose from Screen (72 DPI), eBook (96 DPI), Print (150 DPI), or High Quality (200 DPI) presets. Note: this approach works best for scanned or image-heavy PDFs — it converts text to images.