Contentstack's Content Delivery API at https://cdn.contentstack.io/v3 (region-specific hosts for EU, Azure, and GCP) serves published content. Auth goes in headers, and environment is required.
Find the stack's API key and create a delivery token under Settings → Tokens. Send them as api_key and access_token headers. In the examples they're {{CS_API_KEY}} and {{CS_DELIVERY_TOKEN}}.
Full reference: https://www.contentstack.com/docs/developers/apis/content-delivery-api
curl "https://cdn.contentstack.io/v3/content_types/{{CONTENT_TYPE_UID}}/entries?environment={{ENVIRONMENT}}" \
-H "api_key: {{CS_API_KEY}}" \
-H "access_token: {{CS_DELIVERY_TOKEN}}"
curl "https://cdn.contentstack.io/v3/content_types?include_count=true" \
-H "api_key: {{CS_API_KEY}}" \
-H "access_token: {{CS_DELIVERY_TOKEN}}"