This assumes you have already created an API token and have a base 64 encoded string of the API token. Check out my article FreeKB - Atlassian - Create API token.

Using the base64 encoded string, you should now be able to submit a GET request and get JSON response. For example, to GET Confluence Spaces.

More GET request examples here => The Confluence Cloud REST API

curl \
--request GET \
--header "Accept: application/json" \
--header "Authorization: Basic <base64 encoded string>" \
--url "https://acme.atlassian.net/wiki/api/v2/spaces"| jq

Something like this should be returned.

{
  "results": [
    {
      "spaceOwnerId": "557058:73a84e24-c4ab-4afc-b7ca-0050d3ef0f96",
      "createdAt": "2024-10-13T20:11:24.561Z",
      "authorId": "557058:73a84e24-c4ab-4afc-b7ca-0050d3ef0f96",
      "homepageId": "15335585",
      "icon": null,
      "description": null,
      "status": "current",
      "name": "my first space",
      "key": "A1",
      "id": "15335479",
      "type": "global",
      "_links": {
        "webui": "/spaces/A1"
      },
      "currentActiveAlias": "A1"
    }
  ],
  "_links": {
    "next": "/wiki/api/v2/spaces?cursor=eyJpZCI6MTUzMzU0NzksInNwYWNlU29ydE9yZGVyIjp7ImZpZWxkIjoiSUQiLCJkaXJlY3Rpb24iOiJBU0NFTkRJTkcifSwic3BhY2VTb3J0T3JkZXJWYWx1ZSI6MTUzMzU0Nzl9",
    "base": "https://acme.atlassian.net/wiki"
  }
}

By default, the first 25 spaces will be returned. Notice in the above output there is a "next" endpoint. The "next" endpoint can be used to return the next 25 spaces.

curl \
--silent \
--request GET \
--header "Accept: application/json" \
--header "Authorization: Basic <base64 encoded string>" \
--url "https://acme.atlassian.net/wiki/api/v2/spaces?cursor=eyJpZCI6MTUzMzU0NzksInNwYWNlU29ydE9yZGVyIjp7ImZpZWxkIjoiSUQiLCJkaXJlY3Rpb24iOiJBU0NFTkRJTkcifSwic3BhY2VTb3J0T3JkZXJWYWx1ZSI6MTUzMzU0Nzl9"| jq

The limit parameter can be used to return a specific number of spaces. The value must be between 1 - 250.

curl \
--silent \
--request GET \
--header "Accept: application/json" \
--header "Authorization: Basic <base64 encoded string>" \
--url "https://acme.atlassian.net/wiki/api/v2/spaces?limit=1"| jq