How Pixscaler compresses images
Most image compression tools upload your files to a remote server, process them there, and send the result back. Pixscaler takes a different approach. When you drop a file into the workspace above, the browser reads it directly using the File API. A Web Worker running on your own hardware takes that data, renders the image onto an offscreen canvas, applies the compression settings you chose, and exports the result as a Blob. At no point does any image data travel over the internet.
This matters in three specific ways. First, your files stay private regardless of what is in them. Passport scans, medical photos, confidential product mockups: none of them leave your machine. Second, because there is no network round-trip, compression happens as fast as your hardware allows. On a modern laptop, a batch of 30 high-resolution photos typically completes in a few seconds. Third, the tool works offline. Once the page has loaded, you can disconnect from the internet and the compressor still works.
Quality and file size
Use the quality slider for lossy formats (WebP, AVIF, JPEG). After compression, each row shows the original size, the new size, and the output dimensions so you can judge whether to raise or lower quality before downloading. If a portal or email client enforces a hard file size limit, adjust dimensions and quality and re-run until the listed size meets your requirement—there is no guaranteed single-click way to hit an exact byte cap for every image.
Converting images to WebP and AVIF
WebP and AVIF are the two modern image formats most worth using on the web right now. WebP produces files roughly 25 to 35 percent smaller than JPEG at the same visual quality and has universal browser support. AVIF compresses further than WebP, typically 45 to 55 percent smaller than JPEG, but takes slightly longer to encode.
Both formats are selectable in Pixscaler's format dropdown. For most web use cases, WebP is the right default. Use AVIF for key images on pages where file size is a primary concern and your audience is on modern browsers. Both formats support transparency, so either can replace PNG files with alpha channels.
Resizing images to exact dimensions
When you enter both width and height, the output image is exactly that many pixels wide and tall. If that does not match your source aspect ratio, the image is scaled non-uniformly (stretched or squeezed) to fill the frame—useful when a platform expects a fixed aspect ratio.
When you enter only width or only height, the aspect ratio lock (on by default) keeps the other side proportional to your original. Turn the lock off if you want the missing side to stay at the original pixel size instead.
For platform-specific dimension requirements, the preset pages at the top of this section open the workspace with the correct width, height, and format. You drop the file, tune quality if needed, and download the result.