Old Saxon is an Ingvaeonic language, which means that it belongs to the West Germanic branch of the Germanic languages and that it is particularly closely related to Old English and Old Frisian.
Thus, anyone looking at Old Saxon phonology will recognize some typical West-Germanic phonological features also found in Old English, such as gemination and the different pronunciations of the letter g. Old Saxon was in a direct continuum with Old Dutch, with which it shares the distribution of the reflexes of Proto-Germanic *ai and *au, which monophthongize to /ɛː/ and /ɔː/ unless followed by a semivowel or, in the case of *ai, under the influence of an umlaut.
This contrasts with Old High German, which monophthongizes *ai and *au only in front of certain consonants and word-finally, thus creating no distinction between older *ai and its umlaut.
In a similar vein, Old English merges both Proto-Germanic *au and *auw into /æːɑ/, whereas Old Frisian partially merges older *ai and *au into /ā/.
Old High German: heilant, Old English: hǣlend, Gothic: háiljands.