InDesign is not the best tool for creating web pages, but it is possible to output InDesign files to HTML format.
To export to HTML, go to File > Export, then choose “HTML” from the “Format” drop-down menu.
InDesign Retains Most, but Not All, of the Accessibility Markup
When exporting to HTML, InDesign retains the document title, heading structure, and alt text for images. Overall it does a good job of retaining the accessibility features.
Unfortunately, InDesign does not mark up the header cells in data tables as <th> as it should. It marks them as <td>, which means they are treated by screen readers as data cells instead of header cells. If you export a table from InDesign to HTML, you will need to edit the HTML source code to convert the header cells to <th> tags. InDesign does add <thead> around the header rows in the table, but the <thead> alone is insufficient to mark header cells.
Note: VoiceOver on Mac does interpret the <td> cells within <thead> as header cells and associates the data cells appropriately with the header cells, but none of the other screen readers recognizes the header cells unless they are marked with <th>.