diff --git a/libs/common/src/platform/misc/flags.ts b/libs/common/src/platform/misc/flags.ts
index b3269c8f4e8..297e616e66b 100644
--- a/libs/common/src/platform/misc/flags.ts
+++ b/libs/common/src/platform/misc/flags.ts
@@ -3,6 +3,7 @@
 export type SharedFlags = {
   showPasswordless?: boolean;
   sdk?: boolean;
+  prereleaseBuild?: boolean;
 };
 
 // required to avoid linting errors when there are no flags
diff --git a/libs/common/src/services/api.service.ts b/libs/common/src/services/api.service.ts
index 5f53131719c..f3bd93560b6 100644
--- a/libs/common/src/services/api.service.ts
+++ b/libs/common/src/services/api.service.ts
@@ -126,6 +126,7 @@ import { AppIdService } from "../platform/abstractions/app-id.service";
 import { EnvironmentService } from "../platform/abstractions/environment.service";
 import { LogService } from "../platform/abstractions/log.service";
 import { PlatformUtilsService } from "../platform/abstractions/platform-utils.service";
+import { flagEnabled } from "../platform/misc/flags";
 import { Utils } from "../platform/misc/utils";
 import { SyncResponse } from "../platform/sync";
 import { UserId } from "../types/guid";
@@ -1843,44 +1844,20 @@ export class ApiService implements ApiServiceAbstraction {
     const requestUrl =
       apiUrl + Utils.normalizePath(pathParts[0]) + (pathParts.length > 1 ? `?${pathParts[1]}` : "");
 
-    const headers = new Headers({
-      "Device-Type": this.deviceType,
-    });
-    if (this.customUserAgent != null) {
-      headers.set("User-Agent", this.customUserAgent);
-    }
+    const [requestHeaders, requestBody] = await this.buildHeadersAndBody(
+      authed,
+      hasResponse,
+      alterHeaders,
+      body,
+    );
 
     const requestInit: RequestInit = {
       cache: "no-store",
       credentials: await this.getCredentials(),
       method: method,
     };
-
-    if (authed) {
-      const authHeader = await this.getActiveBearerToken();
-      headers.set("Authorization", "Bearer " + authHeader);
-    }
-    if (body != null) {
-      if (typeof body === "string") {
-        requestInit.body = body;
-        headers.set("Content-Type", "application/x-www-form-urlencoded; charset=utf-8");
-      } else if (typeof body === "object") {
-        if (body instanceof FormData) {
-          requestInit.body = body;
-        } else {
-          headers.set("Content-Type", "application/json; charset=utf-8");
-          requestInit.body = JSON.stringify(body);
-        }
-      }
-    }
-    if (hasResponse) {
-      headers.set("Accept", "application/json");
-    }
-    if (alterHeaders != null) {
-      alterHeaders(headers);
-    }
-
-    requestInit.headers = headers;
+    requestInit.headers = requestHeaders;
+    requestInit.body = requestBody;
     const response = await this.fetch(new Request(requestUrl, requestInit));
 
     const responseType = response.headers.get("content-type");
@@ -1897,6 +1874,51 @@ export class ApiService implements ApiServiceAbstraction {
     }
   }
 
+  private async buildHeadersAndBody(
+    authed: boolean,
+    hasResponse: boolean,
+    body: any,
+    alterHeaders: (headers: Headers) => void,
+  ): Promise<[Headers, any]> {
+    let requestBody: any = null;
+    const headers = new Headers({
+      "Device-Type": this.deviceType,
+    });
+
+    if (flagEnabled("prereleaseBuild")) {
+      headers.set("Is-Prerelease", "true");
+    }
+    if (this.customUserAgent != null) {
+      headers.set("User-Agent", this.customUserAgent);
+    }
+    if (hasResponse) {
+      headers.set("Accept", "application/json");
+    }
+    if (alterHeaders != null) {
+      alterHeaders(headers);
+    }
+    if (authed) {
+      const authHeader = await this.getActiveBearerToken();
+      headers.set("Authorization", "Bearer " + authHeader);
+    }
+
+    if (body != null) {
+      if (typeof body === "string") {
+        requestBody = body;
+        headers.set("Content-Type", "application/x-www-form-urlencoded; charset=utf-8");
+      } else if (typeof body === "object") {
+        if (body instanceof FormData) {
+          requestBody = body;
+        } else {
+          headers.set("Content-Type", "application/json; charset=utf-8");
+          requestBody = JSON.stringify(body);
+        }
+      }
+    }
+
+    return [headers, requestBody];
+  }
+
   private async handleError(
     response: Response,
     tokenError: boolean,