Websites are today one of the most common ways for humans to interact with each other. Evolving from just static pages for companies to highly dynamic social medias, websites are built upon complex techniques and architectures to meet end-user demands. One of the latest techniques are single page applicationswhich makes use of the web browsers capabililities to execute application code. One drawback is that search engines cannot visit the site, nor can script-disabled web browsers. For a single page application to function on all devices a new concept called isomorphism needs to be considered. The aim of this thesis have been to analyze, design and implement an isomorphic web application using modern technologies. The practical work have been applied using an agile project method, while theoretical works are based on previous knowledge and an internet based research. The implementation went through several iterations of trial and error but was finally completed with Facebook's React framework together with a modified version of the Flux architecture. The resulting application was implemented in both Ember and the proposed isomorphic solution. Benchmarks of both implementations were carried out and compared with each other to see how the thesis' isomorphic solution performed. The results shows an performance increase in the isomorphic solution. In conclusion the full application was not implemented due to time limits, but the most performance critical parts were. While only one framework was compared, it would be of interest to compare with more frameworks to give a better performance overview.