Fission track analysis is a long-tested and reliable approach to quantifying the cooling history of natural minerals and glasses for a wide range of thermo- and geochronology applications. Unlike other common thermo- and geochronometric approaches, fission-track analysis may be entirely performed with optical microscopy, avoiding the need for expensive isotopic measurements that require access to clean facilities and mass spectrometers. Advances in computerized microscopy have now routinized the rapid collection of high-resolution, three-dimensional image stacks for digital fission-track analysis – however accessible and flexible platforms for digital fission-track analysis remains largely unavailable. Here I present Fijjiontrack: a new ImageJ plugin for fission track counting and measurement. ImageJ (also available as Fiji with ImageJ2) is a free, open-source, and platform-independent Java-based image processing software popular in biomedical research. This new plugin allows users to measure track density over an arbitrary area, two-dimensional lengths (e.g. Dpar), three-dimensional lengths (e.g. track lengths) and angles (e.g. C-axis correction) on image stacks in a variety of formats, including open formats like OME-TIFF as well as CZI format. The plugin allows users to take advantage of built-in image processing methods to assist with track determination, and run their own algorithms for automated track detection. Users can save and export the information required for age calculation as well as additional details, like spatial information on track density for interpreting eU zonation or track orientation data for annealing experiments. Along with the plugin, a database of mineral standard and external detector mica image stacks is also available for new user training and zeta calibration. As additional image stacks are added to the database, it may also be used for training and standardized testing of artificial intelligence algorithms to automatically detect fission tracks over large areas or for large numbers of grains. Fijjiontrack is designed to be versatile platform for free, accessible, reproducible and archivable fission track analysis with an ultimate goal of broadening the fission track user base and training a global generation of fission trackers.