This is my personal free to use image converter tool. You can use it to convert multiple images to a different image format directly in your browser. It is almost instant on most devices, and the best thing is, that it will never be paid, unlike other image conversion services.
You can visit the website at free-image-converter.vercel.app to convert your images for free.
Don't worry, the images are not being stored on any server, as it is all being done directly in your browser on your device. No one will see anything you ever upload to this service.