The challenges that are most commonly discussed by proponents of open source in government technology relate to changing the culture among technical staff and explaining the value of open tools and systems. But beyond the political concerns and misperceptions, there are practical complications in implementing these tools inside proprietary tech ecosystems like Esri. Although it's becoming easier, injecting open source into the Esri stack can be convoluted, to say the least.For all of its challenges, however, there have been many successful open source implementations in all levels of government, from open data portals to full-scale applications. Using case studies from recent Code for America projects, this talk will identify some of the more difficult challenges and highlight a few techniques for integrating open source geo tools into the Esri stack with a focus on minimizing difficulty for the developer and maximizing benefit for the end user. The talk will focus on web applications and tools while touching on data interoperability, spatial analysis, and trainings/documentation.