Sandhi occurs in many languages, particularly in the phonology of South Asian languages (especially Sanskrit, Tamil, Sinhala, Telugu, Marathi, Hindi, Pali, Kannada, Bengali, Assamese, Malayalam).

Tamil employs Sandhi for certain morphological and syntactic structures.

Most tonal languages have tone sandhi in which the tones of words alter according to certain rules. An example is the behavior of Mandarin Chinese; in isolation, tone 3 is often pronounced as a falling-rising tone. When a tone 3 occurs before another tone 3, however, it changes into tone 2 (a rising tone), and when it occurs before any of the other tones, it is pronounced as a low falling tone with no rise at the end.

In Celtic languages, the consonant mutation sees the initial consonant of a word to change according to its morphological or syntactic environment.

In English phonology, sandhi can be seen when one word ends with a vowel, and the next begins with a vowel.

French liaison and enchaînement can be considered forms of external sandhi.

In Japanese phonology, sandhi is primarily exhibited in rendaku (consonant mutation from unvoiced to voiced when not word-initial, in some contexts) and conversion of つ or く (tsu, ku) to a geminate consonant (orthographically, the sokuon っ), both of which are reflected in spelling.

Korean has sandhi which occurs in the final consonant or consonant cluster, such that a morpheme can have two pronunciations depending on whether or not it is followed by a vowel.