A synthesis tree of 3,245 extant families of Panarthropods was created manually on Treegraph2 utilizing 216 phylogenetic and taxonomic sources. It is inteded for use for ecology, biogeogaphy, comparative biology, and, if possible, conservation research. A full explanation for the construction of the synthesis tree can be accessed in the Methods and References document. NOTE: Several families were mistakenly put into the tree twice (Dynomenidae, Erebonnasteridae, Laemobothriiae, Paraphronimidae, and Tegeocranellidae). Duplicates were removed, and the number of standing families is at 3,223. NOTE2: Errors in the Stomatopod phylogeny were fixed with a redundant source removed. Some explanations in the Methods document were elaborated on. NOTE3: Phylogeny of Araneae was updated, with changes to the topology of Atypoidea, Lycosoidea, Araneoidea, Dionycha, 'Marronoidea', an Austrochiloidea. The families Hexurellidae, Megahexuride, Mecicobothriidae, Dolomedidae, Ancylometidae, Synaphridae, Fonteferridae, Udubidae, Myrmeciculatoridae, Trachycosmidae, Cithaeronidae, Cicurinidae, Telemidae, Archoleptonetidae, Melloinidae, Psilodercidae, and Rhytidicolidae were added. Additionally, Pergieopidae, Theridiidae, Lamponidae, Synotaxidae, and Senoculidae, despite being included in the original source for the topology of Araneae, were omitted by mistake and are now placed in their updated positions. Other changes include the removal of Heptathelidae and Mackenziellidae (as they are now considered synonymous with Liphistiidae and Sminthurididae respectively) (WSC https://wsc.nmbe.ch/ and Collembola.org https://www.collembola.org/), the addition of Adelphacaridae to Palaeacaroidea, and changing the positions of Heteroscorpionidae and Hemiscorpionidae.