diff --git a/packages/app-store/_lib/analytics-schemas.ts b/packages/app-store/_lib/analytics-schemas.ts
index 5bc8466fcf..16b5edbf20 100644
--- a/packages/app-store/_lib/analytics-schemas.ts
+++ b/packages/app-store/_lib/analytics-schemas.ts
@@ -1,5 +1,15 @@
 import { z } from "zod";
 
+/**
+ * Helper to create schemas that accept nullish values but always output string.
+ * Used for tracking IDs that may be null/undefined in the database.
+ */
+const nullishString = () =>
+  z
+    .union([z.string(), z.null(), z.undefined()])
+    .transform((val): string => (typeof val === "string" ? val.trim() : ""));
+
+// URL schema: string input, validates http/https (kept as original to maintain type compatibility)
 export const safeUrlSchema = z
   .string()
   .transform((val) => val.trim())
@@ -16,23 +26,19 @@ export const safeUrlSchema = z
     { message: "Invalid URL format. Must be a valid http or https URL" }
   );
 
-// Schema for tracking IDs that should only contain letters, numbers, underscores, and hyphens
-export const alphanumericIdSchema = z
-  .string()
-  .transform((val) => val.trim())
-  .refine((val) => !val || /^[A-Za-z0-9_-]+$/.test(val), {
-    message: "Invalid ID format. Expected alphanumeric characters, underscores, or hyphens",
-  });
+// Alphanumeric ID schema - accepts nullish for tracking IDs
+export const alphanumericIdSchema = nullishString().refine(
+  (val) => !val || /^[A-Za-z0-9_-]+$/.test(val),
+  { message: "Invalid ID format. Expected alphanumeric characters, underscores, or hyphens" }
+);
 
-// Schema for tracking IDs that should only contain digits
-export const numericIdSchema = z
-  .string()
-  .transform((val) => val.trim())
-  .refine((val) => !val || /^[0-9]+$/.test(val), {
-    message: "Invalid ID format. Expected a numeric ID",
-  });
+// Numeric ID schema - accepts nullish for tracking IDs
+export const numericIdSchema = nullishString().refine(
+  (val) => !val || /^[0-9]+$/.test(val),
+  { message: "Invalid ID format. Expected a numeric ID" }
+);
 
-// Factory for creating prefixed ID schemas (GTM, GA4, Fathom, etc.)
+// Factory for prefixed ID schemas (GTM-, G-, etc.)
 export const createPrefixedIdSchema = (options: {
   prefix?: string;
   addPrefixIfMissing?: boolean;
@@ -41,9 +47,11 @@ export const createPrefixedIdSchema = (options: {
   const { prefix = "", addPrefixIfMissing = false, allowEmpty = true } = options;
 
   return z
-    .string()
-    .transform((val) => {
+    .union([z.string(), z.null(), z.undefined()])
+    .transform((val): string => {
+      if (typeof val !== "string") return "";
       let result = val.trim().toUpperCase();
+      if (!result) return result;
       if (prefix && addPrefixIfMissing) {
         const clean = result.replace(new RegExp(`^${prefix}`, "i"), "");
         result = `${prefix}${clean}`;
diff --git a/packages/app-store/analytics-apps.test.ts b/packages/app-store/analytics-apps.test.ts
index 7b0b6fea95..0fe43255ca 100644
--- a/packages/app-store/analytics-apps.test.ts
+++ b/packages/app-store/analytics-apps.test.ts
@@ -252,4 +252,99 @@ describe("Analytics Apps - Input Validation", () => {
       }
     });
   });
+
+  // Null/undefined handling for embed endpoint (PR 26976)
+  // Schemas accept nullish input and always output string
+  describe("Null/Undefined Handling", () => {
+    it("GTM converts null to empty string", () => {
+      expect(gtmSchema.parse({ trackingId: null }).trackingId).toBe("");
+    });
+
+    it("GA4 converts null to empty string", () => {
+      expect(ga4Schema.parse({ trackingId: null }).trackingId).toBe("");
+    });
+
+    it("Meta Pixel converts null to empty string", () => {
+      expect(metapixelSchema.parse({ trackingId: null }).trackingId).toBe("");
+    });
+
+    it("PostHog converts null to empty string", () => {
+      expect(posthogSchema.parse({ TRACKING_ID: null }).TRACKING_ID).toBe("");
+    });
+
+    it("Fathom converts null to empty string", () => {
+      expect(fathomSchema.parse({ trackingId: null }).trackingId).toBe("");
+    });
+
+    it("Plausible converts null to empty string", () => {
+      expect(plausibleSchema.parse({ trackingId: null }).trackingId).toBe("");
+    });
+
+    it("Matomo converts null to empty string", () => {
+      expect(matomoSchema.parse({ SITE_ID: null }).SITE_ID).toBe("");
+    });
+
+    it("Umami converts null to empty string", () => {
+      expect(umamiSchema.parse({ SITE_ID: null }).SITE_ID).toBe("");
+    });
+
+    it("Twipla converts null to empty string", () => {
+      expect(twiplaSchema.parse({ SITE_ID: null }).SITE_ID).toBe("");
+    });
+
+    it("Insihts converts null to empty string", () => {
+      expect(insihtsSchema.parse({ SITE_ID: null }).SITE_ID).toBe("");
+    });
+
+    it("Databuddy converts null to empty string", () => {
+      expect(databuddySchema.parse({ CLIENT_ID: null }).CLIENT_ID).toBe("");
+    });
+  });
+
+  // Missing key handling - fields should be optional
+  describe("Missing Key Handling", () => {
+    it("GA4 accepts missing trackingId", () => {
+      expect(() => ga4Schema.parse({})).not.toThrow();
+    });
+
+    it("GTM accepts missing trackingId", () => {
+      expect(() => gtmSchema.parse({})).not.toThrow();
+    });
+
+    it("Meta Pixel accepts missing trackingId", () => {
+      expect(() => metapixelSchema.parse({})).not.toThrow();
+    });
+
+    it("Fathom accepts missing trackingId", () => {
+      expect(() => fathomSchema.parse({})).not.toThrow();
+    });
+
+    it("Plausible accepts missing trackingId", () => {
+      expect(() => plausibleSchema.parse({})).not.toThrow();
+    });
+
+    it("PostHog accepts missing TRACKING_ID", () => {
+      expect(() => posthogSchema.parse({})).not.toThrow();
+    });
+
+    it("Matomo accepts missing fields", () => {
+      expect(() => matomoSchema.parse({})).not.toThrow();
+    });
+
+    it("Umami accepts missing SITE_ID", () => {
+      expect(() => umamiSchema.parse({})).not.toThrow();
+    });
+
+    it("Twipla accepts missing SITE_ID", () => {
+      expect(() => twiplaSchema.parse({})).not.toThrow();
+    });
+
+    it("Insihts accepts missing fields", () => {
+      expect(() => insihtsSchema.parse({})).not.toThrow();
+    });
+
+    it("Databuddy accepts missing CLIENT_ID", () => {
+      expect(() => databuddySchema.parse({})).not.toThrow();
+    });
+  });
 });
diff --git a/packages/app-store/gtm/zod.ts b/packages/app-store/gtm/zod.ts
index 71ee5440ab..3e5a311676 100644
--- a/packages/app-store/gtm/zod.ts
+++ b/packages/app-store/gtm/zod.ts
@@ -1,12 +1,11 @@
 import { z } from "zod";
 
 import { eventTypeAppCardZod } from "@calcom/app-store/eventTypeAppCardZod";
-
 import { createPrefixedIdSchema } from "@calcom/app-store/_lib/analytics-schemas";
 
 export const appDataSchema = eventTypeAppCardZod.merge(
   z.object({
-    trackingId: createPrefixedIdSchema({ prefix: "GTM-", addPrefixIfMissing: true, allowEmpty: false }),
+    trackingId: createPrefixedIdSchema({ prefix: "GTM-", addPrefixIfMissing: true, allowEmpty: true }),
   })
 );
 
diff --git a/packages/app-store/insihts/zod.ts b/packages/app-store/insihts/zod.ts
index d8f0b3a24b..7c5431e483 100644
--- a/packages/app-store/insihts/zod.ts
+++ b/packages/app-store/insihts/zod.ts
@@ -1,7 +1,6 @@
 import { z } from "zod";
 
 import { eventTypeAppCardZod } from "@calcom/app-store/eventTypeAppCardZod";
-
 import { alphanumericIdSchema, safeUrlSchema } from "@calcom/app-store/_lib/analytics-schemas";
 
 export const appDataSchema = eventTypeAppCardZod.merge(
diff --git a/packages/app-store/matomo/zod.ts b/packages/app-store/matomo/zod.ts
index ee39ec1697..734829eebc 100644
--- a/packages/app-store/matomo/zod.ts
+++ b/packages/app-store/matomo/zod.ts
@@ -1,7 +1,6 @@
 import { z } from "zod";
 
 import { eventTypeAppCardZod } from "@calcom/app-store/eventTypeAppCardZod";
-
 import { numericIdSchema, safeUrlSchema } from "@calcom/app-store/_lib/analytics-schemas";
 
 export const appDataSchema = eventTypeAppCardZod.merge(
diff --git a/packages/app-store/metapixel/zod.ts b/packages/app-store/metapixel/zod.ts
index 532f72d529..e4399565cd 100644
--- a/packages/app-store/metapixel/zod.ts
+++ b/packages/app-store/metapixel/zod.ts
@@ -4,8 +4,8 @@ import { eventTypeAppCardZod } from "@calcom/app-store/eventTypeAppCardZod";
 
 // Meta Pixel IDs are numeric strings of 15-16 digits
 const metaPixelIdSchema = z
-  .string()
-  .transform((val) => val.trim())
+  .union([z.string(), z.null(), z.undefined()])
+  .transform((val): string => (typeof val === "string" ? val.trim() : ""))
   .refine((val) => val === "" || /^[0-9]{15,16}$/.test(val), {
     message: "Invalid Meta Pixel ID format. Expected a numeric ID (e.g., 1234567890123456)",
   })
diff --git a/packages/app-store/plausible/zod.ts b/packages/app-store/plausible/zod.ts
index df2c16b8bf..fbdc284322 100644
--- a/packages/app-store/plausible/zod.ts
+++ b/packages/app-store/plausible/zod.ts
@@ -5,14 +5,12 @@ import { safeUrlSchema } from "@calcom/app-store/_lib/analytics-schemas";
 
 // Domain schema for Plausible tracking (e.g., example.com, sub.example.com)
 const domainSchema = z
-  .string()
-  .transform((val) => val.trim().toLowerCase())
+  .union([z.string(), z.null(), z.undefined()])
+  .transform((val): string => (typeof val === "string" ? val.trim().toLowerCase() : ""))
   .refine(
     (val) =>
       val === "" || /^(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)*[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/.test(val),
-    {
-      message: "Invalid domain format. Expected format: example.com",
-    }
+    { message: "Invalid domain format. Expected format: example.com" }
   )
   .optional();
 
diff --git a/packages/app-store/posthog/zod.ts b/packages/app-store/posthog/zod.ts
index 26ccc8cbba..b440b94cc0 100644
--- a/packages/app-store/posthog/zod.ts
+++ b/packages/app-store/posthog/zod.ts
@@ -1,13 +1,12 @@
 import { z } from "zod";
 
 import { eventTypeAppCardZod } from "@calcom/app-store/eventTypeAppCardZod";
-
 import { safeUrlSchema } from "@calcom/app-store/_lib/analytics-schemas";
 
 // PostHog Project API Keys (typically start with phc_) - allow alphanumeric to not break legacy data
 const posthogIdSchema = z
-  .string()
-  .transform((val) => val.trim())
+  .union([z.string(), z.null(), z.undefined()])
+  .transform((val): string => (typeof val === "string" ? val.trim() : ""))
   .refine((val) => !val || /^[A-Za-z0-9_]+$/.test(val), {
     message: "Invalid PostHog Project API Key format. Expected alphanumeric characters or underscores",
   })
diff --git a/packages/app-store/twipla/zod.ts b/packages/app-store/twipla/zod.ts
index b337018986..c497d0c5a5 100644
--- a/packages/app-store/twipla/zod.ts
+++ b/packages/app-store/twipla/zod.ts
@@ -4,8 +4,8 @@ import { eventTypeAppCardZod } from "@calcom/app-store/eventTypeAppCardZod";
 
 // Twipla Site IDs can be UUID or alphanumeric strings
 const twiplaSiteIdSchema = z
-  .string()
-  .transform((val) => val.trim())
+  .union([z.string(), z.null(), z.undefined()])
+  .transform((val): string => (typeof val === "string" ? val.trim() : ""))
   .refine((val) => !val || /^[A-Za-z0-9-]+$/.test(val), {
     message: "Invalid Twipla Site ID format. Expected alphanumeric characters or UUID",
   })
diff --git a/packages/app-store/umami/zod.ts b/packages/app-store/umami/zod.ts
index 10b654ce66..5b39b25402 100644
--- a/packages/app-store/umami/zod.ts
+++ b/packages/app-store/umami/zod.ts
@@ -1,21 +1,18 @@
 import { z } from "zod";
 
 import { eventTypeAppCardZod } from "@calcom/app-store/eventTypeAppCardZod";
-
 import { safeUrlSchema } from "@calcom/app-store/_lib/analytics-schemas";
 
 // Umami Website IDs: UUID in v2 (e.g., 4fb7fa4c-5b46-438d-94b3-3a8fb9bc2e8b) or numeric in v1
 const umamiSiteIdSchema = z
-  .string()
-  .transform((val) => val.trim().toLowerCase())
+  .union([z.string(), z.null(), z.undefined()])
+  .transform((val): string => (typeof val === "string" ? val.trim().toLowerCase() : ""))
   .refine(
     (val) =>
       !val ||
       /^[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}$/.test(val) ||
       /^[0-9]+$/.test(val),
-    {
-      message: "Invalid Umami Website ID format. Expected UUID or numeric ID",
-    }
+    { message: "Invalid Umami Website ID format. Expected UUID or numeric ID" }
   )
   .optional();