diff --git a/src/Umbraco.Web.UI.Client/src/core/mocks/browser-handlers.ts b/src/Umbraco.Web.UI.Client/src/core/mocks/browser-handlers.ts
index 014a4e8c61..9cc4f46619 100644
--- a/src/Umbraco.Web.UI.Client/src/core/mocks/browser-handlers.ts
+++ b/src/Umbraco.Web.UI.Client/src/core/mocks/browser-handlers.ts
@@ -1,4 +1,5 @@
 import { handlers as dataTypeHandlers } from './domains/data-type.handlers';
+import { handlers as relationTypeHandlers } from './domains/relation-type.handlers';
 import { handlers as documentTypeHandlers } from './domains/document-type.handlers';
 import { handlers as installHandlers } from './domains/install.handlers';
 import * as manifestsHandlers from './domains/manifests.handlers';
@@ -34,6 +35,7 @@ const handlers = [
 	...documentHandlers,
 	...mediaHandlers,
 	...dataTypeHandlers,
+	...relationTypeHandlers,
 	...documentTypeHandlers,
 	...telemetryHandlers,
 	...publishedStatusHandlers,
diff --git a/src/Umbraco.Web.UI.Client/src/core/mocks/domains/relation-type.handlers.ts b/src/Umbraco.Web.UI.Client/src/core/mocks/domains/relation-type.handlers.ts
new file mode 100644
index 0000000000..dd1bb5acd5
--- /dev/null
+++ b/src/Umbraco.Web.UI.Client/src/core/mocks/domains/relation-type.handlers.ts
@@ -0,0 +1,72 @@
+import { rest } from 'msw';
+import { umbRelationTypeData } from '../data/relation-type.data';
+import { umbracoPath } from '@umbraco-cms/utils';
+
+// TODO: add schema
+export const handlers = [
+	rest.delete<string[]>('/umbraco/backoffice/relation-type/:key', async (req, res, ctx) => {
+		const key = req.params.key as string;
+		if (!key) return;
+
+		umbRelationTypeData.delete([key]);
+
+		return res(ctx.status(200));
+	}),
+
+	rest.get('/umbraco/management/api/v1/tree/relation-type/root', (req, res, ctx) => {
+		const rootItems = umbRelationTypeData.getTreeRoot();
+		const response = {
+			total: rootItems.length,
+			items: rootItems,
+		};
+		return res(ctx.status(200), ctx.json(response));
+	}),
+
+	rest.get('/umbraco/management/api/v1/tree/relation-type/children', (req, res, ctx) => {
+		const parentKey = req.url.searchParams.get('parentKey');
+		if (!parentKey) return;
+
+		const children = umbRelationTypeData.getTreeItemChildren(parentKey);
+
+		const response = {
+			total: children.length,
+			items: children,
+		};
+
+		return res(ctx.status(200), ctx.json(response));
+	}),
+
+	rest.get('/umbraco/management/api/v1/tree/relation-type/item', (req, res, ctx) => {
+		const keys = req.url.searchParams.getAll('key');
+		if (!keys) return;
+		const items = umbRelationTypeData.getTreeItem(keys);
+		return res(ctx.status(200), ctx.json(items));
+	}),
+
+	rest.get(umbracoPath('/relation-type/:key'), (req, res, ctx) => {
+		const key = req.params.key as string;
+		if (!key) return;
+
+		const RelationType = umbRelationTypeData.getByKey(key);
+
+		return res(ctx.status(200), ctx.json(RelationType));
+	}),
+
+	rest.post(umbracoPath('/relation-type/:key'), async (req, res, ctx) => {
+		const data = await req.json();
+		if (!data) return;
+
+		const saved = umbRelationTypeData.save(data);
+
+		return res(ctx.status(200), ctx.json(saved));
+	}),
+
+	rest.put(umbracoPath('/relation-type/:key'), async (req, res, ctx) => {
+		const data = await req.json();
+		if (!data) return;
+
+		const saved = umbRelationTypeData.save(data);
+
+		return res(ctx.status(200), ctx.json(saved));
+	}),
+];