About the pdf tools
A PDF is a container for text, vector drawings, and images with a fixed layout, which is why it looks identical everywhere and why editing one is awkward. Merging and splitting here only rearrange pages: nothing is re-encoded, so the text stays selectable and the quality is untouched. Compression is the exception, since shrinking a PDF means recompressing the photos inside it.
Extracting text works on PDFs that contain text. A scan contains pictures of text, so it needs optical character recognition instead, which is what our image to text tool does with Tesseract. Signing works by drawing or typing a signature onto the page and flattening it in place. All of it runs through pdf-lib and pdf.js in your browser, so contracts and statements never leave your device.