This analysis of current Urantia Book search engines (below) is provided for two reasons: (1) First and foremost to assist students of the revelation in deciding which search engine(s) are most appropriate for their particular use(s), and (2) To foster competition among the various Urantia Book search engine providers to continue their efforts to develop ever-better tools for the students of the Revelation.
UBSearch (FEF) developed by Troy Bishop, was the first comprehensive English [only] Urantia Book search engine, and established the baseline functionality for work that would follow.
UBSS The Urantia Book Simple Search engine, the latest and most advanced Urantia Book search engine designed for the mobile community, extends the features, functionality, and scope of its predecessors by providing robust, multi-lingual searching and viewing features for the English text and all available Urantia Book translations -- for the mobile user.
SmartAid further extends the robust searching and multi-lingual viewing capabilities of UBSE5, by adding simultaneous multi-lingual viewing and synchronization features to facilitate the comparison of different versions of the text, perhaps most notably the original English text with any of its available translations, and also, comparison between various translations themselves. SmartAid also provides an English-only option making it, for some, the best available Urantia Book search option. Also, more advanced students/researchers of the revelation are even using this tool, with its side-by-side capabilities, to compare various sections of the English (or other) text in a side-by-side manner.
UBSE5 (a 'classic' search engine in the style of of UBSearch) extended the features and, more importantly, the scope of UBSearch by providing robust, multi-lingual searching and viewing features for the English text and all available Urantia Book translations. An English vs. Target Language comparison feature is also available.
TruthBook.com (TB) has a commercially-developed UB search engine whose user interface is a bit unfriendly and found quite buggy at the time of evaluation, but it does offer advanced boolean search capabilities - if you need them. Available in English, Spanish, and Portuguese, the two latter versions appear to be using an older version of the text.
Urantia Foundation (UF) has a commercially-developed search engine for all of its versions. Albeit somewhat primitive, where the user interface and term highlighting are lacking, for example, it does offer some boolean search capabilities. Could be used in a pinch.
A list of all available versions of UBSE5, SmartAid, and UBSS search engines is available here.
You may compare the major features of these Search Engines, below