DSM Developer Guide

Synology provides a DSM Developer Guide

You can find the Online Version at Synology DSM 7.2.2 Developer Guide

Or you can download the pdf DSM_Developer_Guide_7_enu.pdf.

Additional Development Information

Here are some additions, as Synology is negligent in updating its documentation.

Web Service

You can define PHP Profiles für Web Services. The PHP Backend is defined like this (Synology is lacking the backend numbers for PHP8.*)

PHP Version	backend	Remarks
5.6	3	Default on DSM < 6
7.0	4
7.1	5
7.2	6
7.3	7
8.0	9	DSM >= 7.0
8.1	10	DSM >= 7.2
8.2	11	DSM >= 7.2
8.4	13	DSM >= 7.2