OHowWow

pdf 相較於 ppt 最大的好處，大概就是在A電腦做的檔案，放到B、C、D、E、F.... 電腦，版位都不會跑掉，只是使用免費版軟體編輯完，通常都會有浮水印。自己看還好，如果是當作簡報給其他人看，這就完全不適用了，以下找了幾個免費且無浮水印的 PDF 編輯軟體：

1. PDFsam Basic

PDFsam Basic 是一款開源且免費的 PDF 編輯工具，專注於拆分、合併、旋轉和重新排序 PDF 文件。它不會添加浮水印，而且可以在 Windows、macOS 和 Linux 上使用。

"OpenShot" is an open source free software, cross-platform (Windows, Mac, Linux), supports a variety of video formats, stability and speed is also very good, is also often updated, providing conversion output, multi-track editing film and sound channel Features, built-in video effects, subtitle effects, can be dragged and applied directly.
Download

Combine multiple pdf files, convert images to pdf files, rearrange files, add watermarks, encrypt, decrypt, etc.

PDF-XChange Viewer (PDF-XChange Lite Free) - PDF reading and annotation tool, which can add annotations, text, lines, lines, graphics, stamps on the PDF, and the best PDF to image function (File → Export), multi-page browsing mode, let you switch more easily when opening multiple files.

OpenProj 1.4 Download
Freeware

PDFUnlock

FreeMyPDF