Holy tradition states that Rupert was a scion of the Frankish royal Merovingian dynasty;[3] he was possibly related to the Robertians, and likely a descendant of Count palatine Chrodbert II.

In his missionary work in Germany Rupert was accompanied by Saints Chuniald and Gislar, but no records of their acts have survived. As bishop at Worms, Rupert was first accepted as a wise and devout dignitary, but the mostly pagan community came to reject him and forced him out of the city by the end of the 7th century.

Rupert then moved to Altötting, where he started his missionary work by preaching to the locals. He would sail down the Danube river, visiting many towns, villages and forts. Soon he had converted a large population along the Danube, reaching southeastward to the Bavarian border with the Pannonian lands, which were under the rule of the Avar Khaganate. Here, he stayed at Lorch, the former Roman city of Lauriacum (today part of Enns), where an early Christian church—the present Basilica of St. Lawrence—already existed.

Warlike conditions in the borderlands made him abandon plans of missionary work in the territories of the Pannonian Avars. Instead, he proceeded along the Roman road via Seekirchen to the ruined city of Juvavum, which he made his base and renamed "Salzburg". As in Lorch, Rupert was able to build on early Christian traditions that were already in place. He re-established the monastic community at St. Peter's Abbey and laid the foundations of Salzburg Cathedral, which was finished by his successor Vergilius. He also founded the Benedictine nunnery of Nonnberg beneath the Festungsberg fortifications, where his niece Erentrude became the first abbess.

Rupert also introduced higher education and other reforms. From Duke Theodo of Bavaria his bishopric received estates around Piding and Reichenhall, where he promoted the development of the local saltworks. Rupert's mission work also spread into the Alps, where the first monastic cell was founded at present-day Bischofshofen about 711.

Rupert reportedly died on Easter Sunday around 710. His mortal remains were transferred to Salzburg Cathedral by Bishop Vergilius on 24 September 774.

He is also known as the "Apostle of the Bavarians" and is patron of several settlements, such as Sankt Ruprecht in Styria and Šentrupert in Slovenia.

Other Saints of the Day
1. Saint Alexander
2. Saint Amator
3. Saint Augusta
4. Saint John of Egypt
5. Saint Philetus

-catholic.org