**Installation** ----------------------------- **System requirements** ~~~~~~~~~~~~~~~~~~~~~~~~ Microsoft Windows: 64-bit operating system, Windows 7 or later Apple macOS: OS X 10.9 (Mavericks) or later 3 gigabytes RAM Display resolution minimum 1440 pixels wide and minimum 650 pixels high. **Technical information** QuickNII consists of two co-located executable components implemented in two programming languages for historical reasons. The GUI component is implemented in MXML+ActionScript (runs on Adobe Integrated Runtime, which is bundled as "captive runtime", requiring no installation). A slicer service running in the background is implemented in Java (and has a bundled JRE requiring no installation). The two components communicate via standard output and local TCP connections (using the loopback interface). **Conditions of use** ~~~~~~~~~~~~~~~~~~~~~~ **Licence:** Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International for the main component. Source code: MIT License. **Citation of the tool:** -RRID on SciCrunch: (QuickNII, RRID:SCR_016854) -Puchades MA, Csucs G, Ledergerber D, Leergaard TB, Bjaalie JG (2019) Spatial registration of serial microscopic brain images to three-dimensional reference atlases with the QuickNII tool. PLOS ONE 14(5): e0216796. https://doi.org/10.1371/journal.pone.0216796 **Download** ~~~~~~~~~~~~~ Download of the software is from Nitrc.org Link: https://www.nitrc.org/projects/quicknii/ Unzipp the QuickNII folder at your desired location. **Versions and release notes** * Version 2.2 (2019-05-28) This release includes several reference atlases. Linux support was added in July 2020. * Version 2.2preview (2019-04-02) Series descriptor builder recognizes multiple numbering variants in filenames (numbers at fixed character position from either end of names, and sequence indicator \_s prefixanywhere) Coordinate transformation to/from Allen CCFv3 added to Mouse package. * Version 2.1 (2018-12-05) First stable version