PDF 圧縮
Reduce the file size of your PDF while maintaining optimal visual quality for uploads and email attachments.
PDFファイルを選択
or drag and drop PDF here
PDF最適化ガイド：圧縮アルゴリズムとファイル軽量化
PDF files can become bulky when they contain high-resolution images, embedded fonts, and complex vectors. Compressing a PDF involves optimizing these assets to reduce file size without compromising readability.
Lossless vs. Lossy PDF Optimization
PDF compression uses two main methods: lossless and lossy. Lossless compression shrinks text streams using algorithms like FlateDecode (Deflate). Lossy compression targets raster images embedded in the document, compressing JPEG data or downsampling images (e.g. from 300 DPI to 150 DPI) to dramatically reduce file sizes.
The Security Advantage of Local Compression
Because PDFs often contain financial statements or confidential records, uploading them to public cloud servers for compression poses privacy risks. DocumentAlter compresses PDFs directly in your browser, keeping your sensitive documents secure.
PDFを圧縮・軽量化する手順（ステップ別ガイド）
Import Target PDF File
Select or drag the PDF document you want to optimize into the compression area.
Configure Optimization Strength
Choose your compression level: Recommended (best quality/size ratio), Extreme (maximum size reduction), or Low.
Optimize and Download
Run the local optimization script to re-compress the document and download the smaller file.
よくあるご質問 (FAQ)
「PDF 圧縮」にファイルをドラッグし、圧縮モードを選択してダウンロードするだけで大幅に容量を削減できます。
テキストの鮮明さを保ちながら不要なメタデータや冗長オブジェクトを効率的に削減するため、視覚的品質は維持されます。
はい、100%安全です。すべての圧縮アルゴリズムはブラウザ内で動作し、ファイルがインターネット上に送信されることはありません。