Block colors are now supported in the API

We have added support for block colors in the Notion Public API. There is now a color keyword for the following block types: paragraph, heading_1, heading_2, heading_3, bulleted_list_item, numbered_list_item, to_do, toggle, callout, quote, and table_of_contents. For these block types, the block color is returned in the block object, and you can use the update block, append block children, and create page endpoints to update the color of existing blocks and create new blocks with color.

The colors supported are default, gray, brown, orange, yellow, green, blue, purple, pink, red, gray_background, brown_background, orange_background, yellow_background, green_background, blue_background, purple_background, pink_background, and red_background.

{
    "object": "block",
    "id": "79bc0ae2-b002-4ecd-92db-870354734aaf",
    "created_time": "2022-03-03T22:49:00.000Z",
    "last_edited_time": "2022-03-03T22:49:00.000Z",
    "created_by": {
        "object": "user",
        "id": "914ff1b3-45c7-48dc-b2c2-be37d21e7695"
    },
    "last_edited_by": {
        "object": "user",
        "id": "914ff1b3-45c7-48dc-b2c2-be37d21e7695"
    },
    "has_children": false,
    "archived": false,
    "type": "callout",
    "callout": {
        "rich_text": [
            {
                "type": "text",
                "text": {
                    "content": "This block has color!",
                    "link": null
                },
                "annotations": {
                    "bold": false,
                    "italic": false,
                    "strikethrough": false,
                    "underline": false,
                    "code": false,
                    "color": "default"
                },
                "plain_text": "This block has color!",
                "href": null
            }
        ],
        "icon": {
            "type": "emoji",
            "emoji": "💡"
        },
        "color": "green_background"
    }
}