JPG to PDF is the tool for pictures. Despite the name, it accepts JPG, JFIF, PNG, WEBP, GIF, BMP, AVIF, SVG and TIFF images, plus HEIC when your browser can open it, as Safari does. A multi-page TIFF from a scanner adds every page to the PDF. Drag the images into order, choose A4, Letter or the image's own size, set the orientation to automatic, portrait or landscape, and pick no margin, small or large. It respects the camera orientation, and JPGs that don't need rotating are embedded as they are, without recompression. Separate pages exist for the most common searches, such as image to PDF, PNG to PDF, photo to PDF, HEIC to PDF, WEBP to PDF, JFIF to PDF, BMP to PDF and TIFF to PDF; they all use the same tool.
TXT to PDF is for text. Paste text or open a .txt file and choose the page size (A4 or Letter), font (Helvetica, Times or Courier), font size and margins. Long lines wrap on their own and new pages are added automatically. It supports Western languages such as English, Spanish and Portuguese; other alphabets and emoji are replaced with "?".
Illustrator files have their own page: AI to PDF. An .ai file saved with "Create PDF Compatible File", the default in Illustrator, is already a PDF inside, so it's delivered as it is with a .pdf extension, ready to open in any PDF viewer.
For a paper document, Scan to PDF is often better than photographing pages and converting them, because it crops each page with perspective correction and applies document filters. For a document you are writing, Word Editor can save it as a PDF through your browser's print dialog.
Which page size to choose depends on where the PDF is going. A4 is the standard in most countries, Letter in the United States and Canada, and the image's own size keeps each photo exactly as it is, with no white borders. For a document that will be printed, a small margin keeps content away from the edge; for something only read on screen, no margin uses the full page. Automatic orientation turns each page to match its image, which helps when you mix portrait and landscape photos. Whatever you choose, drag the images into the final order before creating the file, because each one becomes a page in that sequence.
Once you have the PDF, you can keep working without uploading it again: merge it with other files, add page numbers or compress it before sending.