diff --git a/readthedocs/api/v2/serializers.py b/readthedocs/api/v2/serializers.py
index a897cdc1403..8401266ca76 100644
--- a/readthedocs/api/v2/serializers.py
+++ b/readthedocs/api/v2/serializers.py
@@ -128,6 +128,7 @@ class VersionAdminSerializer(VersionSerializer):
     project = ProjectAdminSerializer()
     canonical_url = serializers.SerializerMethodField()
     build_data = serializers.JSONField(required=False, write_only=True, allow_null=True)
+    addons = serializers.BooleanField(required=False, write_only=True, allow_null=False)
 
     def get_canonical_url(self, obj):
         return obj.project.get_docs_url(
@@ -138,6 +139,7 @@ def get_canonical_url(self, obj):
 
     class Meta(VersionSerializer.Meta):
         fields = VersionSerializer.Meta.fields + [
+            "addons",
             "build_data",
             "canonical_url",
         ]
diff --git a/readthedocs/builds/migrations/0051_add_addons_field.py b/readthedocs/builds/migrations/0051_add_addons_field.py
new file mode 100644
index 00000000000..7b6aeb272ab
--- /dev/null
+++ b/readthedocs/builds/migrations/0051_add_addons_field.py
@@ -0,0 +1,23 @@
+# Generated by Django 3.2.19 on 2023-05-23 07:07
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("builds", "0050_build_readthedocs_yaml_path"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="version",
+            name="addons",
+            field=models.BooleanField(
+                blank=True,
+                default=False,
+                null=True,
+                verbose_name="Inject new addons js library for this version",
+            ),
+        ),
+    ]
diff --git a/readthedocs/builds/models.py b/readthedocs/builds/models.py
index 3916e0e4c44..d8effa31c06 100644
--- a/readthedocs/builds/models.py
+++ b/readthedocs/builds/models.py
@@ -145,7 +145,11 @@ class Version(TimeStampedModel):
         populate_from='verbose_name',
     )
 
+    # TODO: this field (`supported`) could be removed. It's returned only on
+    # the footer API response but I don't think anybody is using this field at
+    # all.
     supported = models.BooleanField(_('Supported'), default=True)
+
     active = models.BooleanField(_('Active'), default=False)
     state = models.CharField(
         _("State"),
@@ -156,7 +160,12 @@ class Version(TimeStampedModel):
         help_text=_("State of the PR/MR associated to this version."),
     )
     built = models.BooleanField(_("Built"), default=False)
+
+    # TODO: this field (`uploaded`) could be removed. It was used to mark a
+    # version as "Manually uploaded" by the core team, but this is not required
+    # anymore. Users can use `build.commands` for these cases now.
     uploaded = models.BooleanField(_("Uploaded"), default=False)
+
     privacy_level = models.CharField(
         _('Privacy Level'),
         max_length=20,
@@ -192,6 +201,13 @@ class Version(TimeStampedModel):
         null=True,
     )
 
+    addons = models.BooleanField(
+        _("Inject new addons js library for this version"),
+        null=True,
+        blank=True,
+        default=False,
+    )
+
     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 d49dd666464..e79cf17bcaf 100644
--- a/readthedocs/doc_builder/director.py
+++ b/readthedocs/doc_builder/director.py
@@ -59,6 +59,9 @@ def __init__(self, data):
         """
         self.data = data
 
+        # Reset `addons` field. It will be set to `True` only when it's built via `build.commands`
+        self.data.version.addons = False
+
     def setup_vcs(self):
         """
         Perform all VCS related steps.
@@ -422,6 +425,10 @@ 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
+
+        # Mark this version to inject the new js client when serving it via El Proxito
+        self.data.version.addons = True
+
         self.store_readthedocs_build_yaml()
 
     def install_build_tools(self):
diff --git a/readthedocs/projects/tasks/builds.py b/readthedocs/projects/tasks/builds.py
index 38b357be785..55b00618351 100644
--- a/readthedocs/projects/tasks/builds.py
+++ b/readthedocs/projects/tasks/builds.py
@@ -600,6 +600,7 @@ def on_success(self, retval, task_id, args, kwargs):
                         "has_epub": "epub" in valid_artifacts,
                         "has_htmlzip": "htmlzip" in valid_artifacts,
                         "build_data": self.data.version.build_data,
+                        "addons": self.data.version.addons,
                     }
                 )
             except HttpClientError:
diff --git a/readthedocs/projects/tests/test_build_tasks.py b/readthedocs/projects/tests/test_build_tasks.py
index 670071c5111..3646d3f8652 100644
--- a/readthedocs/projects/tests/test_build_tasks.py
+++ b/readthedocs/projects/tests/test_build_tasks.py
@@ -299,6 +299,7 @@ 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() == {
+            "addons": False,
             "build_data": None,
             "built": True,
             "documentation_type": "mkdocs",
@@ -552,6 +553,7 @@ 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() == {
+            "addons": False,
             "build_data": None,
             "built": True,
             "documentation_type": "sphinx",
diff --git a/readthedocs/proxito/middleware.py b/readthedocs/proxito/middleware.py
index 85881d0fbe7..b8e93ea0366 100644
--- a/readthedocs/proxito/middleware.py
+++ b/readthedocs/proxito/middleware.py
@@ -289,10 +289,25 @@ def process_request(self, request):  # noqa
         return None
 
     def add_hosting_integrations_headers(self, request, response):
+        addons = False
         project_slug = getattr(request, "path_project_slug", "")
+        version_slug = getattr(request, "path_version_slug", "")
+
         if project_slug:
             project = Project.objects.get(slug=project_slug)
+
+            # Check for the feature flag
             if project.has_feature(Feature.HOSTING_INTEGRATIONS):
+                addons = True
+            else:
+                # Check if the version forces injecting the addons (e.g. using `build.commands`)
+                version = (
+                    project.versions.filter(slug=version_slug).only("addons").first()
+                )
+                if version and version.addons:
+                    addons = True
+
+            if addons:
                 response["X-RTD-Hosting-Integrations"] = "true"
 
     def _get_https_redirect(self, request):
diff --git a/readthedocs/proxito/tests/test_headers.py b/readthedocs/proxito/tests/test_headers.py
index c19bc817dd2..9cc2573f798 100644
--- a/readthedocs/proxito/tests/test_headers.py
+++ b/readthedocs/proxito/tests/test_headers.py
@@ -143,6 +143,18 @@ def test_user_domain_headers(self):
         self.assertEqual(r[http_header], http_header_value)
         self.assertEqual(r[http_header_secure], http_header_value)
 
+    def test_hosting_integrations_header(self):
+        version = self.project.versions.get(slug=LATEST)
+        version.addons = True
+        version.save()
+
+        r = self.client.get(
+            "/en/latest/", secure=True, HTTP_HOST="project.dev.readthedocs.io"
+        )
+        self.assertEqual(r.status_code, 200)
+        self.assertIsNotNone(r.get("X-RTD-Hosting-Integrations"))
+        self.assertEqual(r["X-RTD-Hosting-Integrations"], "true")
+
     @override_settings(ALLOW_PRIVATE_REPOS=False)
     def test_cache_headers_public_version_with_private_projects_not_allowed(self):
         r = self.client.get(