The lavaangui package provides a free, open-source graphical user interface for the lavaan package. The core feature is that models can be specified by drawing path diagrams and fitted models visualized via interactive path diagrams.

There are three main ways to use the lavaangui package.

1. Web application: The easiest is to visit https://lavaangui.org/ and use it as a web application. This requires no additional software besides a web browser. The main downside of this is that the webserver is likely slower than your computer. So, fitting complicated models might take a long time. The app is likely also more responsive on your computer.

2. Local web application: After installing the lavaangui package (see below), you can start a local version of the web application via the lavaangui() command.

3. Interactive plots: lavaangui can also be used for plotting lavaan models that were created in R. For this, use plot_lavaan(fit). This will create a path diagram of your model. The core difference compared to other packages for plotting lavaan models is that the resulting plot is interactive. That is, you can change its appearance easily, for example, by dragging around nodes with your mouse. After customizing a diagram, use export_plot(fit, "diagram.png") to save that diagram to a file (PNG, JPG, SVG, or PDF) without any further user intervention.

An extensive tutorial on using lavaangui is available at https://www.tandfonline.com/doi/full/10.1080/10705511.2024.2420678.

For the web application, no installation is necessary. Simply go to https://lavaangui.org/. The web application should work with any modern browser. It is continuously being tested with: Chrome, Edge, Safari, Firefox, and Opera.

You can install the latest version of the R package as usual using the following command:

install.packages("lavaangui")

You can start the lavaangui web application by typing

library(lavaangui)
lavaangui()

into your R console.

Alternatively, you can also use the command lavaangui(fit), where fit is any supported fitted lavaan object. This will initialize the web application with the model (and data) contained in fit. For example, the following code initializes the web application with a three factor model.

library(lavaan)
library(lavaangui)
HS.model <- ' visual  =~ x1 + x2 + x3
              textual =~ x4 + x5 + x6
              speed   =~ x7 + x8 + x9 '

fit <- cfa(HS.model, data = HolzingerSwineford1939)
lavaangui(fit)

To obtain an interactive plot of your fitted model, use the plot_lavaan(fit) function:

library(lavaan)
library(lavaangui)
HS.model <- ' visual  =~ x1 + x2 + x3
              textual =~ x4 + x5 + x6
              speed   =~ x7 + x8 + x9 '

fit <- cfa(HS.model, data = HolzingerSwineford1939)
plot_lavaan(fit)

A common challenge with diagram tools is the trade-off between customizability and reproducibility: either you tweak diagrams manually and lose the ability to regenerate them from a script, or you script everything and give up fine-grained control over appearance. export_plot() resolves this by separating the two steps. First use plot_lavaan(fit) to interactively arrange the diagram to your liking. The layout you created is automatically saved. export_plot() then renders that saved layout directly to a file (PNG, JPG, SVG, or PDF), so the same diagram can be reproduced at any time from a script without further manual interaction.

library(lavaan)
library(lavaangui)
HS.model <- ' visual  =~ x1 + x2 + x3
              textual =~ x4 + x5 + x6
              speed   =~ x7 + x8 + x9 '

fit <- cfa(HS.model, data = HolzingerSwineford1939)
# Step 1: customize and save a layout interactively
plot_lavaan(fit)
# Step 2: export that layout to a file
export_plot(fit, "diagram.png")

If you use lavaangui in your research, please cite the following paper:

Karch, J. D. (2025). lavaangui: A Web-Based Graphical Interface for Specifying Lavaan Models by Drawing Path Diagrams. Structural Equation Modeling: A Multidisciplinary Journal, 1-12. https://doi.org/10.1080/10705511.2024.2420678