Image Converter

Client-side image conversion uses modern web standards such as the HTML5 Canvas API, OffscreenCanvas, and Web Workers. When you upload an image, your browser decodes the pixel grid locally and draws it onto a canvas. The browser then encodes the canvas pixels into the target format (such as JPG, PNG, WEBP, or AVIF) and generates a local download URL. Your images are never uploaded to any remote server, giving you complete privacy.

Lossy formats (like JPG, WebP, and AVIF) achieve tiny file sizes by discarding subtle color and luminance details that are hard for the human eye to perceive. Lossless formats (like PNG) compress the image without altering any pixels, preserving perfect quality but resulting in larger file sizes. WebP and AVIF can operate in both lossy and lossless modes.

The JPG format does not support transparency (an alpha channel). When converting transparent images (such as transparent PNG logos) to JPG, the transparent areas will naturally turn black by default. ToolZeno lets you flatten transparent areas using a custom background color (such as solid White, Black, or any custom hex color) to ensure your output looks clean and professional.

AVIF is supported for decoding in almost all modern browsers. However, canvas-based AVIF encoding is still experimental in some browsers. ToolZeno automatically checks your browser's capabilities and will warn you or disable AVIF options if your browser does not support it, providing WEBP or PNG as reliable fallbacks.

Because conversion is processed entirely in your browser's memory (RAM), there is no fixed file size limit. However, processing very large files (e.g. above 75MB) or huge batches of files simultaneously may slow down mobile browsers. We recommend converting large images individually to optimize performance.