Orion

Orion is a desktop PDF editor that works entirely offline: open a document, add text, images, shapes and annotations, reorganize its pages — then save a normal PDF that any other reader can open. It isn't a wrapper around a web service: everything happens on your machine, and the original file stays untouched until you press Save.

Text added with the tool is real, selectable, searchable PDF text, not an image; annotations — highlights, underlines, sticky notes — are written as standard PDF annotations that any other reader understands. Pages are reordered by dragging thumbnails, split every N pages, or merged from several documents in an order you choose.

Behind the scenes, the interface never touches the PDF file directly: it edits an in-memory model, reading the file only to render it and writing it only on save — which is what makes undo cheap, crash recovery a simple serialization, and the original file safe. Distributed as standalone builds for Windows, macOS and Linux, under the AGPL v3 license, with a commercial license available for closed-product use.