Many users are looking for some information about how to export indesign documents to pdf format, usually when they do not have access to Adobe InDesign itself. Whilst it's true that some 3rd party solutions for InDesign conversions exists, it will never be 100% reliable to convert your .indd files and using Adobe InDesign is the preferred option for indd to pdf conversion. We do not knnw about any program that can be used only as indd to pdf converter, simply because InDesign formats are proprietary and closed, meaning they are usually not supported in 3rd party apps, which makes any kind of indd conversion without InDesign almost impossible.
It might be that similar alternatives like QuarkXpress support some versions of InDesign files, but that might not apply for every version of both the program or InDesign files. Nevertheless, some users reported to us that you can potentially export .indd files to PDF format directly from your Adobe Creative Cloud account (you can create one for free), but this option may have been (or already was) removed in some later versions and is thus no longer viable. If it still works, it is likely the only way how to convert indesign documents to pdf online.
Mac users also have an option with Art View program, an app that supports viewing (and possibly printing to PDF) of various Creative Cloud documents, including .indd documents from Adobe InDesign.Open INDD file Open PDF file
Professional desktop document publishing software from Adobe
Mac version od Adobe's popular document designing and publishing software
A dedicated viewer for Adobe Creative Cloud documents
A design software used to create rich documents for web or print
Software fro document design and publishing