What format is used to upload custom themes to Power BI?

Custom themes for Power BI are uploaded in the JSON format. This is because JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write, and easy for machines to parse and generate. In Power BI, themes defined in JSON format allow users to set consistent colors, fonts, and styles across their reports and dashboards, enhancing the visual coherence of their data presentations.

JSON files specifically enable the expression of complex data structures and attributes that Power BI requires to apply those theme settings effectively. This format supports the hierarchical and structured nature of theme properties, making it ideal for defining the various aspects like colors for visuals, font styles, and more, which are not easily captured in simpler formats like CSV or TXT. PHP, being a server-side scripting language, does not apply in this context as it is not a data format for uploading themes.