diff --git a/dockerfiles/nginx/proxito.conf.template b/dockerfiles/nginx/proxito.conf.template
index 65ee44bb7c8..dfe4fbd18c5 100644
--- a/dockerfiles/nginx/proxito.conf.template
+++ b/dockerfiles/nginx/proxito.conf.template
@@ -88,6 +88,17 @@ server {
         proxy_hide_header Content-Security-Policy;
         set $content_security_policy $upstream_http_content_security_policy;
         add_header Content-Security-Policy $content_security_policy always;
+
+        # This header allows us to decide whether or not inject the script at CloudFlare level
+        # Now, I'm injecting it in all the NGINX responses because `sub_filter` is not allowed inside an `if` statement.
+        set $rtd_hosting_integrations $upstream_http_x_rtd_hosting_integrations;
+        add_header X-RTD-Hosting-Integrations $rtd_hosting_integrations always;
+
+        # Inject our own script dynamically
+        # TODO: find a way to make this work _without_ running `npm run dev` from the `readthedocs-client` repository
+        sub_filter '</head>' '<script language="javascript" src="http://localhost:8000/readthedocs-client.js"></script>\n</head>';
+        sub_filter_last_modified on;
+        sub_filter_once on;
     }
 
     # Serve 404 pages here
diff --git a/readthedocs/api/v2/serializers.py b/readthedocs/api/v2/serializers.py
index 4a5c03e758a..aad6ac57c43 100644
--- a/readthedocs/api/v2/serializers.py
+++ b/readthedocs/api/v2/serializers.py
@@ -101,7 +101,7 @@ class VersionSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = Version
-        fields = (
+        fields = [
             'id',
             'project',
             'slug',
@@ -116,7 +116,7 @@ class Meta:
             'has_epub',
             'has_htmlzip',
             'documentation_type',
-        )
+        ]
 
 
 class VersionAdminSerializer(VersionSerializer):
@@ -124,6 +124,12 @@ class VersionAdminSerializer(VersionSerializer):
     """Version serializer that returns admin project data."""
 
     project = ProjectAdminSerializer()
+    build_data = serializers.JSONField(required=False, write_only=True)
+
+    class Meta(VersionSerializer.Meta):
+        fields = VersionSerializer.Meta.fields + [
+            "build_data",
+        ]
 
 
 class BuildCommandSerializer(serializers.ModelSerializer):
diff --git a/readthedocs/builds/migrations/0048_add_build_data.py b/readthedocs/builds/migrations/0048_add_build_data.py
new file mode 100644
index 00000000000..94a68c30fa0
--- /dev/null
+++ b/readthedocs/builds/migrations/0048_add_build_data.py
@@ -0,0 +1,22 @@
+# Generated by Django 3.2.18 on 2023-03-13 15:15
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("builds", "0047_build_default_triggered"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="version",
+            name="build_data",
+            field=models.JSONField(
+                default=None,
+                null=True,
+                verbose_name="Data generated at build time by the doctool (`readthedocs-build.yaml`).",
+            ),
+        ),
+    ]
diff --git a/readthedocs/builds/models.py b/readthedocs/builds/models.py
index fafc68cecaa..dc83b11c34b 100644
--- a/readthedocs/builds/models.py
+++ b/readthedocs/builds/models.py
@@ -65,11 +65,9 @@
     BITBUCKET_COMMIT_URL,
     BITBUCKET_URL,
     DOCTYPE_CHOICES,
-    GITHUB_BRAND,
     GITHUB_COMMIT_URL,
     GITHUB_PULL_REQUEST_COMMIT_URL,
     GITHUB_URL,
-    GITLAB_BRAND,
     GITLAB_COMMIT_URL,
     GITLAB_MERGE_REQUEST_COMMIT_URL,
     GITLAB_URL,
@@ -186,6 +184,12 @@ class Version(TimeStampedModel):
         ),
     )
 
+    build_data = models.JSONField(
+        _("Data generated at build time by the doctool (`readthedocs-build.yaml`)."),
+        default=None,
+        null=True,
+    )
+
     objects = VersionManager.from_queryset(VersionQuerySet)()
     # Only include BRANCH, TAG, UNKNOWN type Versions.
     internal = InternalVersionManager.from_queryset(partial(VersionQuerySet, internal_only=True))()
diff --git a/readthedocs/doc_builder/director.py b/readthedocs/doc_builder/director.py
index c7aecd62910..3c7e824374a 100644
--- a/readthedocs/doc_builder/director.py
+++ b/readthedocs/doc_builder/director.py
@@ -2,6 +2,7 @@
 import tarfile
 
 import structlog
+import yaml
 from django.conf import settings
 from django.utils.translation import gettext_lazy as _
 
@@ -187,6 +188,7 @@ def build(self):
         self.build_epub()
 
         self.run_build_job("post_build")
+        self.store_readthedocs_build_yaml()
 
         after_build.send(
             sender=self.data.version,
@@ -392,6 +394,7 @@ def run_build_commands(self):
         # Update the `Version.documentation_type` to match the doctype defined
         # by the config file. When using `build.commands` it will be `GENERIC`
         self.data.version.documentation_type = self.data.config.doctype
+        self.store_readthedocs_build_yaml()
 
     def install_build_tools(self):
         """
@@ -625,3 +628,37 @@ def get_build_env_vars(self):
     def is_type_sphinx(self):
         """Is documentation type Sphinx."""
         return "sphinx" in self.data.config.doctype
+
+    def store_readthedocs_build_yaml(self):
+        # load YAML from user
+        yaml_path = os.path.join(
+            self.data.project.artifact_path(
+                version=self.data.version.slug, type_="html"
+            ),
+            "readthedocs-build.yaml",
+        )
+
+        if not os.path.exists(yaml_path):
+            log.debug("Build output YAML file (readtehdocs-build.yaml) does not exist.")
+            return
+
+        try:
+            with open(yaml_path, "r") as f:
+                data = yaml.safe_load(f)
+        except Exception:
+            # NOTE: skip this work for now until we decide whether or not this
+            # YAML file is required.
+            #
+            # NOTE: decide whether or not we want this
+            # file to be mandatory and raise an exception here.
+            return
+
+        log.info("readthedocs-build.yaml loaded.", path=yaml_path)
+
+        # TODO: validate the YAML generated by the user
+        # self._validate_readthedocs_build_yaml(data)
+
+        # Copy the YAML data into `Version.build_data`.
+        # It will be saved when the API is hit.
+        # This data will be used by the `/_/readthedocs-config.json` API endpoint.
+        self.data.version.build_data = data
diff --git a/readthedocs/projects/models.py b/readthedocs/projects/models.py
index bf502c1fce5..e42a381c3cf 100644
--- a/readthedocs/projects/models.py
+++ b/readthedocs/projects/models.py
@@ -1884,6 +1884,7 @@ def add_features(sender, **kwargs):
     CANCEL_OLD_BUILDS = "cancel_old_builds"
     DONT_CREATE_INDEX = "dont_create_index"
     USE_RCLONE = "use_rclone"
+    HOSTING_INTEGRATIONS = "hosting_integrations"
 
     FEATURES = (
         (ALLOW_DEPRECATED_WEBHOOKS, _('Allow deprecated webhook views')),
@@ -2058,6 +2059,10 @@ def add_features(sender, **kwargs):
             USE_RCLONE,
             _("Use rclone for syncing files to the media storage."),
         ),
+        (
+            HOSTING_INTEGRATIONS,
+            _("Inject 'readthedocs-client.js' as <script> HTML tag in responses."),
+        ),
     )
 
     projects = models.ManyToManyField(
diff --git a/readthedocs/projects/tasks/builds.py b/readthedocs/projects/tasks/builds.py
index 20ca5a13bfa..d1b4f31a6d1 100644
--- a/readthedocs/projects/tasks/builds.py
+++ b/readthedocs/projects/tasks/builds.py
@@ -103,7 +103,10 @@ class TaskData:
     build_commit: str = None
 
     start_time: timezone.datetime = None
+
+    # pylint: disable=unsubscriptable-object
     environment_class: type[DockerBuildEnvironment] | type[LocalBuildEnvironment] = None
+
     build_director: BuildDirector = None
     config: BuildConfigV1 | BuildConfigV2 = None
     project: APIProject = None
@@ -572,7 +575,7 @@ def get_valid_artifact_types(self):
                             artifact_type=artifact_type
                         )
                     )
-                elif artifact_format_files == 0:
+                if artifact_format_files == 0:
                     raise BuildUserError(
                         BuildUserError.BUILD_OUTPUT_HAS_0_FILES.format(
                             artifact_type=artifact_type
@@ -598,6 +601,7 @@ def on_success(self, retval, task_id, args, kwargs):
                         "has_pdf": "pdf" in valid_artifacts,
                         "has_epub": "epub" in valid_artifacts,
                         "has_htmlzip": "htmlzip" in valid_artifacts,
+                        "build_data": self.data.version.build_data,
                     }
                 )
             except HttpClientError:
diff --git a/readthedocs/projects/tests/test_build_tasks.py b/readthedocs/projects/tests/test_build_tasks.py
index 16cff2d3170..d9a637edc74 100644
--- a/readthedocs/projects/tests/test_build_tasks.py
+++ b/readthedocs/projects/tests/test_build_tasks.py
@@ -216,6 +216,7 @@ def test_build_updates_documentation_type(self, load_yaml_config):
         assert self.requests_mock.request_history[7]._request.method == "PATCH"
         assert self.requests_mock.request_history[7].path == "/api/v2/version/1/"
         assert self.requests_mock.request_history[7].json() == {
+            "build_data": None,
             "built": True,
             "documentation_type": "mkdocs",
             "has_pdf": True,
@@ -457,6 +458,7 @@ def test_successful_build(
         assert self.requests_mock.request_history[7]._request.method == "PATCH"
         assert self.requests_mock.request_history[7].path == "/api/v2/version/1/"
         assert self.requests_mock.request_history[7].json() == {
+            "build_data": None,
             "built": True,
             "documentation_type": "sphinx",
             "has_pdf": True,
diff --git a/readthedocs/proxito/middleware.py b/readthedocs/proxito/middleware.py
index ba6299b33c6..b17e483da98 100644
--- a/readthedocs/proxito/middleware.py
+++ b/readthedocs/proxito/middleware.py
@@ -26,6 +26,7 @@
     unresolver,
 )
 from readthedocs.core.utils import get_cache_tag
+from readthedocs.projects.models import Feature, Project
 
 log = structlog.get_logger(__name__)
 
@@ -278,9 +279,17 @@ def process_request(self, request):  # noqa
 
         return None
 
+    def add_hosting_integrations_headers(self, request, response):
+        project_slug = getattr(request, "path_project_slug", "")
+        if project_slug:
+            project = Project.objects.get(slug=project_slug)
+            if project.has_feature(Feature.HOSTING_INTEGRATIONS):
+                response["X-RTD-Hosting-Integrations"] = "true"
+
     def process_response(self, request, response):  # noqa
         self.add_proxito_headers(request, response)
         self.add_cache_headers(request, response)
         self.add_hsts_headers(request, response)
         self.add_user_headers(request, response)
+        self.add_hosting_integrations_headers(request, response)
         return response
diff --git a/readthedocs/proxito/tests/test_hosting.py b/readthedocs/proxito/tests/test_hosting.py
new file mode 100644
index 00000000000..e6f407358af
--- /dev/null
+++ b/readthedocs/proxito/tests/test_hosting.py
@@ -0,0 +1,123 @@
+"""Test hosting views."""
+
+import django_dynamic_fixture as fixture
+import pytest
+from django.conf import settings
+from django.contrib.auth.models import User
+from django.test import TestCase, override_settings
+from django.urls import reverse
+
+from readthedocs.builds.constants import EXTERNAL, INTERNAL, LATEST
+from readthedocs.builds.models import Build
+from readthedocs.projects.constants import PUBLIC
+from readthedocs.projects.models import Project
+
+
+@override_settings(
+    PUBLIC_DOMAIN="dev.readthedocs.io",
+    PUBLIC_DOMAIN_USES_HTTPS=True,
+)
+@pytest.mark.proxito
+class TestReadTheDocsConfigJson(TestCase):
+    def setUp(self):
+        self.user = fixture.get(User, username="user")
+        self.user.set_password("user")
+        self.user.save()
+
+        self.project = fixture.get(
+            Project,
+            slug="project",
+            language="en",
+            privacy_level=PUBLIC,
+            external_builds_privacy_level=PUBLIC,
+            repo="git://10.10.0.1/project",
+            programming_language="words",
+            single_version=False,
+            users=[self.user],
+            main_language_project=None,
+        )
+        self.project.versions.update(
+            privacy_level=PUBLIC,
+            built=True,
+            active=True,
+            type=INTERNAL,
+            identifier="1a2b3c",
+        )
+        self.version = self.project.versions.get(slug=LATEST)
+        self.build = fixture.get(
+            Build,
+            version=self.version,
+        )
+
+    def test_get_config(self):
+        r = self.client.get(
+            reverse("proxito_readthedocs_config_json"),
+            {"url": "https://project.dev.readthedocs.io/en/latest/"},
+            secure=True,
+            HTTP_HOST="project.dev.readthedocs.io",
+        )
+        assert r.status_code == 200
+
+        expected = {
+            "comment": "THIS RESPONSE IS IN ALPHA FOR TEST PURPOSES ONLY AND IT'S GOING TO CHANGE COMPLETELY -- DO NOT USE IT!",
+            "project": {
+                "slug": self.project.slug,
+                "language": self.project.language,
+                "repository_url": self.project.repo,
+                "programming_language": self.project.programming_language,
+            },
+            "version": {
+                "slug": self.version.slug,
+                "external": self.version.type == EXTERNAL,
+            },
+            "build": {
+                "id": self.build.pk,
+            },
+            "domains": {
+                "dashboard": settings.PRODUCTION_DOMAIN,
+            },
+            "readthedocs": {
+                "analytics": {
+                    "code": None,
+                }
+            },
+            "features": {
+                "analytics": {
+                    "code": None,
+                },
+                "external_version_warning": {
+                    "enabled": True,
+                    "query_selector": "[role=main]",
+                },
+                "non_latest_version_warning": {
+                    "enabled": True,
+                    "query_selector": "[role=main]",
+                    "versions": [
+                        "latest",
+                    ],
+                },
+                "doc_diff": {
+                    "enabled": True,
+                    "base_url": "https://project.dev.readthedocs.io/en/latest/index.html",
+                    "root_selector": "[role=main]",
+                    "inject_styles": True,
+                    "base_host": "",
+                    "base_page": "",
+                },
+                "flyout": {
+                    "translations": [],
+                    "versions": [
+                        {"slug": "latest", "url": "/en/latest/"},
+                    ],
+                    "downloads": [],
+                    "vcs": {
+                        "url": "https://github.com",
+                        "username": "readthedocs",
+                        "repository": "test-builds",
+                        "branch": self.version.identifier,
+                        "filepath": "/docs/index.rst",
+                    },
+                },
+            },
+        }
+        assert r.json() == expected
diff --git a/readthedocs/proxito/urls.py b/readthedocs/proxito/urls.py
index 43ac7119aed..1973c342431 100644
--- a/readthedocs/proxito/urls.py
+++ b/readthedocs/proxito/urls.py
@@ -40,6 +40,7 @@
 from readthedocs.constants import pattern_opts
 from readthedocs.core.views import HealthCheckView
 from readthedocs.projects.views.public import ProjectDownloadMedia
+from readthedocs.proxito.views.hosting import ReadTheDocsConfigJson
 from readthedocs.proxito.views.serve import (
     ServeDocs,
     ServeError404,
@@ -114,6 +115,12 @@
         ServeStaticFiles.as_view(),
         name="proxito_static_files",
     ),
+    # readthedocs-config.js
+    path(
+        f"{DOC_PATH_PREFIX}readthedocs-config/",
+        ReadTheDocsConfigJson.as_view(),
+        name="proxito_readthedocs_config_json",
+    ),
 ]
 
 core_urls = [
diff --git a/readthedocs/proxito/views/hosting.py b/readthedocs/proxito/views/hosting.py
new file mode 100644
index 00000000000..3552ac52375
--- /dev/null
+++ b/readthedocs/proxito/views/hosting.py
@@ -0,0 +1,128 @@
+"""Views for hosting features."""
+
+import structlog
+from django.conf import settings
+from django.http import JsonResponse
+from django.views import View
+
+from readthedocs.builds.constants import EXTERNAL
+from readthedocs.core.mixins import CDNCacheControlMixin
+from readthedocs.core.resolver import resolver
+from readthedocs.core.unresolver import unresolver
+
+log = structlog.get_logger(__name__)  # noqa
+
+
+class ReadTheDocsConfigJson(CDNCacheControlMixin, View):
+    def get(self, request):
+
+        url = request.GET.get("url")
+        if not url:
+            return JsonResponse(
+                {"error": "'url' GET attribute is required"},
+                status=400,
+            )
+
+        unresolved_domain = request.unresolved_domain
+        project = unresolved_domain.project
+
+        # TODO: why the UnresolvedURL object is not injected in the `request` by the middleware.
+        # Is is fine to calculate it here?
+        unresolved_url = unresolver.unresolve_url(url)
+        version = unresolved_url.version
+
+        # TODO: use Referrer header or GET arguments for Version / Build
+        project.get_default_version()
+        build = version.builds.last()
+
+        # TODO: define how it will be the exact JSON object returned here
+        # NOTE: we could use the APIv3 serializers for some of these objects
+        # if we want to keep consistency. However, those may require some
+        # extra db calls that we probably want to avoid.
+        data = {
+            "comment": (
+                "THIS RESPONSE IS IN ALPHA FOR TEST PURPOSES ONLY"
+                " AND IT'S GOING TO CHANGE COMPLETELY -- DO NOT USE IT!"
+            ),
+            "project": {
+                "slug": project.slug,
+                "language": project.language,
+                "repository_url": project.repo,
+                "programming_language": project.programming_language,
+            },
+            "version": {
+                "slug": version.slug,
+                "external": version.type == EXTERNAL,
+            },
+            "build": {
+                "id": build.pk,
+            },
+            "domains": {
+                "dashboard": settings.PRODUCTION_DOMAIN,
+            },
+            "readthedocs": {
+                "analytics": {
+                    "code": settings.GLOBAL_ANALYTICS_CODE,
+                },
+            },
+            "features": {
+                "analytics": {
+                    "code": project.analytics_code,
+                },
+                "external_version_warning": {
+                    "enabled": True,
+                    "query_selector": "[role=main]",
+                },
+                "non_latest_version_warning": {
+                    "enabled": True,
+                    "query_selector": "[role=main]",
+                    "versions": list(
+                        project.versions.filter(active=True)
+                        .only("slug")
+                        .values_list("slug", flat=True)
+                    ),
+                },
+                "doc_diff": {
+                    "enabled": True,
+                    # "http://test-builds-local.devthedocs.org/en/latest/index.html"
+                    "base_url": resolver.resolve(
+                        project=project,
+                        version_slug=project.get_default_version(),
+                        language=project.language,
+                        filename=unresolved_url.filename,
+                    ),
+                    "root_selector": "[role=main]",
+                    "inject_styles": True,
+                    # NOTE: `base_host` and `base_page` are not required, since
+                    # we are constructing the `base_url` in the backend instead
+                    # of the frontend, as the doc-diff extension does.
+                    "base_host": "",
+                    "base_page": "",
+                },
+                "flyout": {
+                    "translations": [],
+                    "versions": [
+                        {
+                            "slug": version.slug,
+                            "url": f"/{project.language}/{version.slug}/",
+                        }
+                        for version in project.versions.filter(active=True).only("slug")
+                    ],
+                    "downloads": [],
+                    # TODO: get this values properly
+                    "vcs": {
+                        "url": "https://github.com",
+                        "username": "readthedocs",
+                        "repository": "test-builds",
+                        "branch": version.identifier,
+                        "filepath": "/docs/index.rst",
+                    },
+                },
+            },
+        }
+
+        # Update this data with the one generated at build time by the doctool
+        if version.build_data:
+            data.update(version.build_data)
+
+        return JsonResponse(data, json_dumps_params=dict(indent=4))
diff --git a/scripts/circle/install_node.sh b/scripts/circle/install_node.sh
index bfde0987a35..da9cdb4f106 100755
--- a/scripts/circle/install_node.sh
+++ b/scripts/circle/install_node.sh
@@ -2,10 +2,11 @@
 set -ev
 if [ $NODE_VERSION ]
 then
-  curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.2/install.sh | bash
-  source ~/.nvm/nvm.sh
-  nvm install $NODE_VERSION
-  nvm use $NODE_VERSION
+  git clone https://github.com/asdf-vm/asdf.git ~/.asdf --branch v0.11.3
+  . "$HOME/.asdf/asdf.sh"
+  asdf plugin add nodejs https://github.com/asdf-vm/asdf-nodejs.git
+  asdf install nodejs $NODE_VERSION
+  asdf global nodejs $NODE_VERSION
   npm install -g bower
   npm install
   bower install