RMBG is a free online image background removal (image masking) application available across multiple platforms. It incorporates various open-source AI models (RMBG itself is also open-source) to assist users in automatically removing backgrounds without requiring any configuration or account registration. This service supports batch processing of up to 20 images at a time, with each image not exceeding 5 MB. APP Recommendations
RMBG can be used directly in a browser or downloaded as an application for Windows, macOS, and Linux. Its standout feature is privacy and data security: the background removal process runs solely on the user's device, and images are never uploaded to third-party servers.
The Free Resources Network Community has compiled a handy guide titled “Online Background Removal Tools: 39 Free Online Tools Recommended with Tutorials.” If you find RMBG unable to correctly remove backgrounds from your images, besides switching to different AI models, you may also consider trying other services.
User Guide
After launching RMBG, click “Select your files here” on the right to choose the images you want to remove backgrounds from (or simply drag and drop them). You can process up to 20 images at a time, with each file not exceeding 5 MB. Background removal will be handled automatically with no customization options available.
Switch between different AI models under “Model,” such as U2netp, Modnet, Briaai, and Silueta. If the default model doesn't provide satisfactory background removal, try selecting a different model—each excels at processing different types of content. 
RMBG processes backgrounds extremely quickly. Completed images appear below. Click the “Download” button on the far right to save the background-removed image.
Three reasons it's worth trying:
Completely free and open-source! No registration or payment required. The open-source nature ensures secure usage.
The background removal process runs entirely locally. Images are never leaked or uploaded to third-party servers.
Supports multiple AI models, processing up to 20 images per session.