Setup and access
An online tool opens in the tab you already have. There is no install, no license, and no version to update, and nothing is left behind on a shared or work computer. That matters when you have one quick job and a deadline.
Desktop software needs a download, disk space, and permission to install, which is often blocked on office machines. In return it works offline, handles very large files without a browser memory ceiling, and keeps every feature a click away once it is open.
Where your files are processed
The honest answer is that it varies. Many web tools upload your file to a server for processing, which matters for contracts, ID scans, and client work. Others run entirely in the browser, so the file never leaves the device in the first place.
Filekind is the second kind: images and PDFs are processed locally in the browser and never uploaded, with no signup and no watermark. Desktop apps also keep files on the machine, but check the fine print on cloud sync before you send sensitive material anywhere.
Features, limits, and volume
Desktop editors usually win on depth: layers, batch queues, advanced color, plugins, and fine control over compression. If you process hundreds of files a day or build layouts, that control earns its place in your workflow.
For single files and small sets, browser tools are faster to start and often free. They do have limits, such as maximum file size, pixel dimensions, and page counts, so check those before you plan a large job. Match the tool to the volume: one image is a browser task, and a full catalog rewrite is a desktop task.