I am searching for library or api for converting FROM Plain text, MS Word/Excel/Powerpoint (DOC, DOCX, XLS, XLSX), PDF, RTF, OpenDocument (ODT, ODS, ODP, ODG) TO PDF. I found some, but i want opinion if somebody has faced with that.
Libre Office is the best choice I'm aware of because:
- it supports most if not all of the formats you've listed
- it has an API that you can use (command line or programmatic)
- it has SDKs for different languages so you can drive it from multiple programming languages.
- there are third-party applications that can leverage it for providing different / simpler API options (JODConverter - open source though no longer developed I think, Docmosis - commercial [please note I work for Docmosis])
- the conversions are very good (though not perfect)
- it is multi-platform, multi lingual.
- it is actively being developed by a broad community
- it is open source
The other option is to find multiple tools that have suitable APIs and combine them to get the conversions you need. It is plausible you could get better results, but the effort/build/maintenance will be much higher.