Due to climate change, heat stress is an increasing health risk in cities that requires adaptation measures from both citizens and city planning. This study proposes a routing service for the reduction of solar exposure and investigates its potential to reduce heat stress from the individual as well as from the planning perspective. The solar exposure of the pedestrian paths in the city of Heidelberg, Germany, was modeled throughout the day and subsequently integrated into a specialized routing service. The aggregated average of solar exposure of simulated pedestrian trips across the city could be reduced by 12 to 26%. In some cases, the solar exposure of a route could be reduced up to 90% with only a length increase of 12% at noon, the most critical time of day in regard to heat intake. This makes it a promising option for citizens to effectively reduce but not completely eliminate their heat stress. Therefore, action from city planners is still necessary. A network analysis identified critical roads in the city where built measures would have the greatest impact on reducing the heat stress of pedestrians. This provides the base for follow-up investigations in cooperation with citizens and planners. Our approach also supports the shift toward sustainable urban mobility as prioritized by both the EU Green Deal and the UN SDGs. To adapt car-focused cities and make them walkable it is essential to provide pleasant routes, resting points, and, regarding the increasing temperatures, shade. Our project shows that a shade-preferring routing service for pedestrians can both help in analyzing the road network to find focus areas for adaptation measures as well as providing a solution for inner city areas where many detours are possible to reduce the solar exposure of individuals. In addition to the analysis presented here, a functional and publicly accessible routing app is available specifically for Heidelberg at https://heal.openrouteservice.org.