TI 84 Calculator Online is an independent, open-source web project that provides a free browser-based emulator of the Texas Instruments TI-84 Plus CE graphing calculator. It is not affiliated with, sponsored by, or endorsed by Texas Instruments, whose name and calculator model are trademarks of the company. The service is designed for students, teachers, parents, and professionals who need access to advanced calculation and graphing tools without purchasing a physical calculator or installing software. It works on computers, tablets, and smartphones through modern web browsers, with JavaScript enabled and an internet connection for initial loading.

The emulator offers graphing for functions, parametric and polar equations, and sequences, as well as statistical analysis, regression, and plots such as histograms and box plots. Its tools also include arithmetic, trigonometry, logarithms, matrices, complex numbers, distributions, lists, tables, zoom and trace controls, and TI-BASIC programming. Users operate it with a mouse or touchscreen and can adjust its size for their screen.