There are a few open-source programs that you can use to produce nice data visualization.
First, you have Tableau Public, which is great for creating basic charts and graphs from raw data. It includes a variety of visualization types that you can customize and export to HTML, PDF, and other formats.
Second, you can use the free version of the Chart.js library. It’s excellet for creating bar graphs, line graphs, and pie charts. It requires some programming experience, since you need to input the data into the library, but once the data is in, you can customize the look and feel of your visualizations using HTML and CSS.
Third, you have D3.js, which is one of the most popular libraries for data visualization. It allows you to create complex and interactive visuals, such as bubble charts and network graphs. It has a steep learning curve, but if you’re willing to invest a bit of time into learning the library, you’ll be able to make some amazing visuals.
Overall, there are plenty of free options for data visualization software, so it’s up to you to decide which one works best for you. Good luck!