Yes, the Eurail Global Pass does work in Switzerland as well as 32 other European countries. However you cannot buy a Eurail One Country Pass for Switzerland. The Swiss Travel Pass is thus a better option for travel only within Switzerland.

Whether you need a Swiss Travel Pass in addition to a Eurail Pass depends entirely on your specific itinerary within Switzerland. A Eurail Pass covers the main intercity "SBB" trains and some international routes, but it has significant limitations compared to the all-inclusive Swiss Travel Pass. The Eurail Pass generally does not cover local city transport like trams and buses in Zurich or Geneva, nor does it include the majority of private mountain railways, cable cars, and funiculars, which are the highlight of a Swiss trip. While Eurail offers a 25% to 50% discount on some mountain excursions like the Jungfraujoch, the Swiss Travel Pass often provides these same routes for free or at a steeper discount. Additionally, the Swiss Travel Pass includes free entry to over 500 museums across the country. If you are only taking three or four major trains between big cities, Eurail is likely sufficient. However, if your goal is to explore the deep Alps, use Lake Brienz or Lake Thun steamers, and utilize the comprehensive local postal bus network, the Swiss Travel Pass offers far superior value and convenience that the Eurail Pass simply cannot match in 2026.