File Compressor

Data

Compress images, PDFs, documents, ZIP archives, and code files in your browser with before/after comparison.

What is file compression?

File compression reduces file sizes by removing unnecessary data. For images, this means re-encoding with more efficient codecs like WebP at adjustable quality levels. For documents like DOCX, XLSX, and PPTX (which are ZIP-based internally), compression means re-packing their contents at a higher compression level. For text-based files like JSON, CSS, JavaScript, and HTML, compression means minification — removing whitespace, comments, and redundant syntax while preserving functionality. Smaller files mean faster load times, lower bandwidth costs, and quicker deployments.

Client-side compression techniques

This tool uses your browser's built-in Canvas API to re-encode images as WebP with an adjustable quality slider. WebP typically produces files 25-35% smaller than JPEG at equivalent visual quality. Office documents (DOCX, XLSX, PPTX) and ZIP archives are decompressed and re-packed at maximum compression level — since many tools save with fast but suboptimal compression, re-compressing often yields 10-25% savings. For text files, the tool applies format-specific minification: JSON is parsed and re-serialized without whitespace, CSS has comments and unnecessary spaces removed, JavaScript has comments stripped, and HTML has inter-tag whitespace collapsed. All processing happens locally — no files are uploaded to any server.

When to compress files

Compress images before deploying to production, adding to Git repositories, or uploading to CMS platforms. Optimize DOCX and PPTX files before sending via email or uploading to shared drives. Re-compress ZIP archives that were packed with fast compression. Minify JSON fixtures before embedding in test files or API responses. Minify CSS and JavaScript when you need a quick size check without a full build pipeline. Batch compression lets you process multiple files at once, making it ideal for project-wide optimization sweeps.

Frequently Asked Questions

Is my data uploaded to a server?

No. All compression happens entirely in your browser using the Canvas API for images, ZIP re-compression for documents, and string manipulation for text files. Your files never leave your device.

What file types are supported?

Images: JPEG, PNG, WebP, GIF, BMP (re-encoded as WebP). PDFs: optimized by stripping metadata and rebuilding the document structure. Documents: DOCX, XLSX, PPTX, ODT, ODS, ODP, EPUB (ZIP re-compression). Archives: ZIP, JAR, APK (re-compressed at max level). Code/Text: JSON, CSS, JS, HTML, SVG, XML, Python, Go, Rust, and 20+ more (minified by removing whitespace and comments).

How does PDF compression work?

PDFs are optimized by loading the document, copying all pages into a fresh structure, and stripping unnecessary metadata (title, author, keywords, producer). This removes orphan objects and unused resources, typically reducing file size by 10-30% without affecting content or visual quality.

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