Image Compressor
Compress JPEG, PNG, and WebP images with adjustable quality in your browser. Reduce file sizes by up to 90% with real-time preview and batch support. No uploads.
How to Use
Compress images to reduce file size in four steps:
- Upload your images — Drag and drop one or more images onto the upload area, or click to browse. The tool accepts JPEG, PNG, WebP, BMP, and GIF formats. Multiple files are supported for batch compression — each image is processed independently with its own before/after comparison.
- Choose output format — Select JPEG for photographs and complex images (best size reduction with lossy compression), WebP for modern web delivery (30-50% smaller than JPEG at equivalent quality), or PNG for graphics requiring transparency or pixel-perfect lossless output.
- Adjust quality — Use the quality slider (1-100) to control the compression strength. Higher values preserve more visual detail at larger file sizes. For most photographs, 70-85 produces excellent results with significant size reduction. The tool shows the compressed size and savings percentage in real time as you adjust.
- Download compressed images — Click the download button on each image card to save the compressed version. The filename preserves the original name with the new format extension. A green savings badge confirms the file size reduction achieved.
All compression runs locally in your browser using the Canvas API. Your images are never uploaded to any server.
About This Tool
Image compression reduces file size by removing data that contributes least to perceived visual quality. There are two fundamental approaches: lossy compression discards information permanently to achieve dramatic size reductions, while lossless compression reorganizes data without any loss. This tool uses the browser's built-in Canvas API to apply both strategies depending on the output format selected.
JPEG compression uses the Discrete Cosine Transform (DCT) algorithm to convert spatial pixel data into frequency components. High-frequency detail (fine textures, subtle gradients) is quantized more aggressively at lower quality settings, producing smaller files at the cost of visible artifacts around sharp edges. The quality parameter (1-100) controls the quantization table: at quality 85, most photographs are visually indistinguishable from the original while achieving 60-80% file size reduction.
WebP compression was developed by Google as a modern alternative to JPEG and PNG. Its lossy mode uses predictive coding and an arithmetic entropy coder that typically achieves 25-35% smaller files than JPEG at equivalent visual quality. WebP is supported by all modern browsers (Chrome, Firefox, Safari 14+, Edge) and is recommended for web images where broad compatibility is needed.
PNG compression applies the DEFLATE algorithm (LZ77 + Huffman coding) losslessly, meaning every pixel is preserved exactly. PNG is ideal for screenshots, diagrams, logos, and any image requiring transparency. Since the quality parameter does not apply to PNG, this tool outputs PNG at the browser's default compression level.
The compression pipeline works by loading the image into an HTMLImageElement, drawing it onto an off-screen <canvas>, and then calling canvas.toBlob() with the target MIME type and quality parameter. For JPEG output, the canvas is pre-filled with a white background since JPEG does not support transparency — transparent regions in PNG or WebP sources are composited over white before encoding.
Why Use This Tool
Image compression is essential across many workflows where file size impacts performance, cost, or usability:
- Web performance — Images account for 40-60% of total page weight on most websites. Compressing hero images and thumbnails from 2MB to 200KB dramatically improves Largest Contentful Paint (LCP) scores and reduces bandwidth costs. Google Core Web Vitals directly penalize slow-loading pages in search rankings.
- Email attachments — Most email providers limit attachment sizes to 10-25MB. A batch of 20 smartphone photos at 4MB each exceeds these limits. Compressing to quality 80 typically reduces each photo to 800KB-1.2MB while preserving visual quality for viewing on screens.
- Social media and messaging — Platforms like Instagram, Twitter, and WhatsApp re-compress uploaded images. Pre-compressing to WebP at quality 85 gives you control over the visual tradeoff before the platform applies its own lossy encoding pass.
- Cloud storage and backups — Photo libraries from smartphones accumulate gigabytes per year. Compressing older archives by 60-70% extends storage quotas without deleting memories. A 50GB photo library can often be reduced to 15-20GB with minimal visual impact.
- E-commerce product images — Online stores display hundreds of product photos per category page. Optimizing each image to under 100KB enables fast page loads that reduce bounce rates and increase conversion rates. Studies show each 100ms of load time improvement increases revenue by 1%.
This tool processes everything locally in your browser. No images are uploaded, stored, or transmitted to any server — making it safe for personal photos, client work, and confidential content.