76 open-source Office & Documents projects

Office & Documents (File Formats): open-source projects that exist because someone reverse engineered a closed product, sorted by GitHub stars.

1. SheetJS★ 36,344 · slowing

   Spreadsheet toolkit reading XLS, XLSB, Lotus, Quattro Pro and many legacy formats

2. LibreOffice★ 4,564 · active · C++

   Office suite with import filters for reverse-engineered MS Office and other formats

3. oletools★ 3,439 · active · Python

   Python tools to analyze MS OLE2 files and Office documents

4. Apache POI★ 2,283 · active · Java

   Java API for Microsoft binary and OOXML Office formats

5. xlrd★ 2,206 · active · Python

   Python library for reading legacy Excel BIFF (.xls) files

6. hwp.js★ 1,307 · slowing · TypeScript

   Open-source web viewer and parser for Hancom HWP documents

7. MDB Tools★ 1,180 · active · C

   Read Microsoft Access databases on Unix

8. KindleUnpack★ 1,102 · active · Python

   Unpacks Amazon Kindle/Kindlegen MOBI/AZW3 ebooks

9. msg-extractor★ 855 · active · Python

   Extracts emails and attachments from Outlook .msg files

10. MSGReader★ 555 · active · C#

    C# reader for Outlook .msg and .eml files without Outlook

11. apple_cloud_notes_parser★ 544 · active · Ruby

    Parser for Apple Notes databases from iOS/macOS backups

12. libesedb★ 381 · active · C

    Library and tools for Extensible Storage Engine (ESE/EDB) databases

13. libpff★ 374 · active · C

    Library and tools for Outlook PFF/OFF (PST/OST) files

14. MPXJ★ 361 · active · Java

    Reads Microsoft Project MPP files and other schedule formats (Primavera, Asta, Phoenix)

15. pyhwp★ 301 · active · Python

    Python parser for Hancom HWP v5 word processor files

16. java-libpst★ 274 · dormant · Java

    Pure Java library for reading Outlook PST files

17. olefile★ 274 · slowing · Python

    Python package to parse, read and write Microsoft OLE2/Compound File Binary files

18. iWorkFileFormat★ 273 · dormant · C++

    Documentation of the reverse-engineered iWork '13 file format

19. CHMLib★ 267 · dormant · C

    Library for reading Microsoft ITSS/CHM compiled help files

20. hwp-rs★ 233 · dormant · Rust

    Rust parser and tools for Hancom HWP documents

21. reMarkableSync★ 179 · slowing · C#

    OneNote add-in that imports notes by parsing reMarkable's proprietary notebook format

22. pbixray★ 174 · active · Python

    Power BI .pbix and PowerPivot data model parser

23. pyOneNote★ 152 · slowing · Python

    Python parser for OneNote .one files that extracts embedded objects

24. HyperCardPreview★ 143 · dormant · Swift

    macOS app that opens and displays HyperCard stacks from the reverse-engineered format

25. remarkable-layers★ 121 · archived · Python

    Python module for reading and writing reMarkable lines files

26. ProPresenter7-Proto★ 119 · active

    Reverse engineered protobuf definitions for ProPresenter 7 file formats

27. OnyxNoteRenderer★ 114 · dormant · Python

    Renders PDFs from Onyx Boox Note backup files (proprietary note format)

28. lines-are-beautiful★ 113 · dormant · C++

    C++ file API for the reMarkable tablet's proprietary .lines notebook format

29. onenote.rs★ 91 · active · Rust

    Rust parser for Microsoft OneNote .one/.onetoc2 files (MS-ONESTORE)

30. catdoc★ 89 · dormant · C

    Command-line converter of legacy Microsoft Word documents to text

31. cronodump★ 88 · dormant · Python

    Converter for the proprietary Cronos database format

32. remarkable-fs★ 87 · dormant · Python

    FUSE filesystem exposing reMarkable's internal xochitl document store as normal files

33. re-lab★ 85 · dormant · Python

    Joint effort reverse engineering proprietary file formats for open source apps

34. Antiword★ 83 · active · C

    Free reader for Microsoft Word binary documents

35. Onyx-Boox-Annotation-Highlight-Extractor★ 83 · slowing · TypeScript

    Extracts highlights and annotations from Onyx Boox reading-notes exports

36. rm-dl-annotated★ 83 · dormant · Shell

    Export annotated PDFs by rendering reMarkable's proprietary annotation layers

37. libolecf★ 80 · active · C

    Library and tools for the OLE 2 Compound File format

38. kindling★ 61 · active · Rust

    Reverse-engineered kindlegen MOBI/KF8 builder in Rust, ~7,000x faster

39. BabylonToHtml★ 58 · slowing · C#

    Convert Babylon .bgl dictionaries to structured HTML

40. pychm★ 58 · slowing · Python

    Python bindings for CHMLib to read Microsoft CHM help files

41. msgreader (JS)★ 57 · active · TypeScript

    JavaScript reader for Outlook .msg files

42. libpst★ 51 · slowing · C

    Library for reading Microsoft Outlook PST files

43. libvisio★ 47 · active · C++

    Parser for Microsoft Visio file formats (re-lab reverse engineering)

44. stackimport★ 43 · dormant · C++

    Reads HyperCard stacks and converts them to XML and images

45. helpdeco★ 38 · active · C

    Decompiles Windows WinHelp (.hlp) files back to RTF and project files

46. sdocx★ 31 · active · Rust

    Reverse-engineered tooling and SDK for Samsung Notes (.sdocx) files

47. boox-notes-backup-parser★ 29 · slowing · Python

    Parses Onyx Boox Notes backup folders and extracts pages

48. wsconvert★ 20 · active · Python

    Converts WordStar documents to Markdown

49. FileMaker-XMLsnippet-Claude-Skill★ 19 · active

    Reverse-engineered spec of FileMaker's undocumented script XML clipboard format

50. libetonyek★ 19 · active · C++

    Parser for Apple Keynote, Pages and Numbers documents

51. MisterDiagram★ 17 · active · Rust

    Clean-room Rust core for Microsoft Visio .vsdx files and ShapeSheet, with a CLI

52. zee-rp★ 17 · active · Python

    Reader and writer for native Axure RP 11 documents via a reverse-engineered binary-record codec

53. hypercard-stack-uploader★ 16 · dormant · HTML

    Imports classic HyperCard stacks and exports them as HTML or JSON

54. reMarkable-kaitai★ 16 · dormant · Kaitai Struct

    Kaitai Struct specifications for the reMarkable binary .rm notebook format

55. libmspub★ 14 · active · C++

    Parser for Microsoft Publisher documents

56. libfole★ 13 · active · C

    Library for Object Linking and Embedding (OLE) data types

57. wv★ 12 · dormant · C

    Library for importing Microsoft Word 2-2003 binary documents

58. ezpzfile-xdw★ 11 · active · Rust

    Open-source reader and annotator for Fuji Xerox DocuWorks .xdw/.xbd files with a format spec

59. librm_lines★ 11 · active · C++

    C++ library to read, write and render reMarkable v6 .rm lines files

60. parser-for-goodnotes★ 10 · active · HTML

    Parser for the closed GoodNotes document format, reverse-engineered with LLMs

61. libstaroffice★ 8 · active · C++

    Import filter for legacy binary StarOffice/StarWriter/StarCalc documents

62. OpenJTD rjtd★ 7 · active · Rust

    Reverse-engineered Ichitaro JTD/JTT word processor format; Rust reader/renderer

63. libabw★ 5 · active · C++

    Document Liberation library that reads AbiWord documents (GitHub mirror)

64. dissect.ole★ 4 · active · Python

    Python parser for the OLE compound file format

65. libhlp★ 2 · active · Rust

    Pure Rust reader for WinHelp (.hlp) files including LZ77 and phrase decompression

66. Tika-JTD★ 2 · active · Kotlin

    Apache Tika parser that extracts text from Ichitaro (.jtd/.jtt) documents

67. libetonyek★ 0

    Library for importing Apple Keynote, Pages and Numbers documents

68. libgsf★ 0

    Structured file I/O library including Microsoft OLE2 compound document support

69. libmspub★ 0

    Library for importing Microsoft Publisher documents, from LibreOffice's Document Liberation Project

70. libmwaw★ 0

    Imports many legacy Mac document formats (MacWrite, ClarisWorks, MacDraw, WriteNow and more)

71. libpagemaker★ 0

    Document Liberation library that imports Adobe/Aldus PageMaker documents

72. libqxp★ 0

    Document Liberation library that imports QuarkXPress 3.1-4.1 documents

73. libstaroffice★ 0

    Library for importing legacy StarOffice binary documents

74. libwpd★ 0

    Library for importing reverse-engineered WordPerfect documents

75. libwps★ 0

    Imports Microsoft Works, Lotus 1-2-3, Quattro Pro and other legacy DOS/Windows documents

76. wvWare★ 0

    Library and tools for reading Microsoft Word binary documents