Custom Data Extension

Custom Data format allows extension authors to easily extend VS Code's HTML / CSS language support without having to write code.

The two Contribution Points for using custom data in an extension are:

  • contributes.html.customData
  • contributes.css.customData

For example, by including this section in an extension's package.json:

  "contributes": {
    "html": {
      "customData": ["./html.html-data.json"]
    "css": {
      "customData": ["./css.css-data.json"]

VS Code will load the HTML/CSS entities defined in both files and provide language support such as auto-completion and hover information for those entities.

You can find the custom-data-sample at microsoft/vscode-extension-samples.