Guang yun text data
The best web app displaying Guang yun data is 韻典網, providing views of both the full text, page images, and phonological structure. The site does not provide the raw data from which the views derive, but provides links to sources that do.
This project 漢字データベースプロジェクト provides data of the complete text of the Guang yun in XML format, including the (unpunctuated) text of individual entries, and the preface texts. Fan qie spellings are given by marking them up in their original positions in the text with xml tags. Editorial emendations are also marked up with tags. The text files contain many Unicode non-BMP characters, so importing this data into other formats requires that this be taken into consideration (use of utf8mb4 in MySQL, for example). GPL license.
The most refined Guang yun data, including punctuated and carefully edited text, parallels with the Qie yun 切韻 manuscripts, links to manuscript images, and a sophisticated, nice-lookinng interface is provided by this site: Web韻圖. Very impressive, and actively maintained. The underlying data is not made available except via the web interface.
There is a wealth of information on べんぞう（伊藤祥司）展開書庫のページ, but much of it is rather hard to navigate. License not clear.
Guang yun image data
Page images of Guang yun editions are available from a number of sources. The only ones released under an explicitly free license that I am aware of are the Si ku quan shu 四庫全書 editions available through archive.org. These are the 重修廣韻 and the 原本廣韻.
Libraries with publicly available digitized Guang yun editions include:
- Waseda University – may be downloaded as color images or PDFs
- Tokyo University – may be downloaded as B&W PDFs
- 1674 澤存堂 edition (apparently identical page layout to the Waseda 1704 printing.)
- National Diet Library (viewable online in color, but no downloadable format.)
- Said to be Song print, though no date given (apparently identical page layout to the Waseda 1704 printing.)
- Harvard (color page scans, no option for downloading a copy for local use.)
- IDP manuscripts – use this list for call numbers. Examples include: