diff --git a/lib/config.test.js b/lib/config.test.js
index 92be806..5292667 100644
--- a/lib/config.test.js
+++ b/lib/config.test.js
@@ -3,6 +3,14 @@ import { DCN_DEFAULTS, getConfig } from "./config";
 const defaultConsent = DCN_DEFAULTS.consent;
 
 describe("getConfig", () => {
+  beforeEach(() => {
+    jest.spyOn(crypto, "randomUUID").mockReturnValue("0");
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
   it("returns the default config when no overrides are provided", () => {
     expect(getConfig({ host: "host", site: "site" })).toEqual({
       host: "host",
@@ -10,6 +18,7 @@ describe("getConfig", () => {
       cookies: true,
       initPassport: true,
       consent: defaultConsent,
+      sessionID: "0",
     });
   });
 
@@ -28,6 +37,7 @@ describe("getConfig", () => {
       cookies: false,
       initPassport: false,
       consent: defaultConsent,
+      sessionID: "0",
     });
   });
 
diff --git a/lib/config.ts b/lib/config.ts
index 240fc73..eded239 100644
--- a/lib/config.ts
+++ b/lib/config.ts
@@ -18,6 +18,7 @@ type InitConfig = {
 
 type ResolvedConfig = Required<Omit<InitConfig, "consent">> & {
   consent: Consent;
+  sessionID: string;
 };
 
 const DCN_DEFAULTS = {
@@ -39,6 +40,7 @@ function getConfig(init: InitConfig): ResolvedConfig {
     cookies: init.cookies ?? DCN_DEFAULTS.cookies,
     initPassport: init.initPassport ?? DCN_DEFAULTS.initPassport,
     consent: DCN_DEFAULTS.consent,
+    sessionID: generateSessionID(),
   };
 
   if (init.consent?.static) {
@@ -50,5 +52,9 @@ function getConfig(init: InitConfig): ResolvedConfig {
   return config;
 }
 
+function generateSessionID(): string {
+  return crypto.randomUUID();
+}
+
 export type { InitConsent, CMPApiConfig, InitConfig, ResolvedConfig };
 export { getConfig, DCN_DEFAULTS };
diff --git a/lib/core/network.test.js b/lib/core/network.test.js
index ef37fcf..cf3c2b2 100644
--- a/lib/core/network.test.js
+++ b/lib/core/network.test.js
@@ -8,6 +8,7 @@ describe("buildRequest", () => {
       host: "host",
       site: "site",
       consent: { reg: "can", gpp: "gpp", gppSectionIDs: [1, 2] },
+      sessionID: "123",
     };
 
     const req = { method: "GET" };
@@ -20,6 +21,7 @@ describe("buildRequest", () => {
     expect([...url.searchParams.entries()]).toEqual([
       ["query", "string"],
       ["osdk", `web-${buildInfo.version}`],
+      ["sid", "123"],
       ["reg", "can"],
       ["gpp", "gpp"],
       ["gpp_sid", "1,2"],
diff --git a/lib/core/network.ts b/lib/core/network.ts
index 7cd6b2a..c5a127e 100644
--- a/lib/core/network.ts
+++ b/lib/core/network.ts
@@ -7,6 +7,7 @@ function buildRequest(path: string, config: ResolvedConfig, init?: RequestInit):
 
   const url = new URL(`${site}${path}`, `https://${host}`);
   url.searchParams.set("osdk", `web-${buildInfo.version}`);
+  url.searchParams.set("sid", config.sessionID);
 
   if (config.consent.reg) {
     url.searchParams.set("reg", config.consent.reg);
diff --git a/lib/edge/resolve.test.js b/lib/edge/resolve.test.js
index eb4cf36..a873971 100644
--- a/lib/edge/resolve.test.js
+++ b/lib/edge/resolve.test.js
@@ -3,6 +3,14 @@ import { TEST_HOST, TEST_SITE, TEST_BASE_URL } from "../test/mocks";
 import { parseResolveResponse, Resolve } from "./resolve";
 
 describe("resolve", () => {
+  beforeEach(() => {
+    jest.spyOn(crypto, "randomUUID").mockReturnValue("0");
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
   test("forwards identifier when present", () => {
     const config = getConfig({ host: TEST_HOST, site: TEST_SITE });
     const fetchSpy = jest.spyOn(window, "fetch");
@@ -11,14 +19,14 @@ describe("resolve", () => {
     expect(fetchSpy).toHaveBeenCalledWith(
       expect.objectContaining({
         method: "GET",
-        url: `${TEST_BASE_URL}/v1/resolve?id=id&osdk=web-0.0.0-experimental&cookies=yes`,
+        url: `${TEST_BASE_URL}/v1/resolve?id=id&osdk=web-0.0.0-experimental&sid=0&cookies=yes`,
       })
     );
 
     Resolve(config);
     expect.objectContaining({
       method: "GET",
-      url: `${TEST_BASE_URL}/v1/resolve?osdk=web-0.0.0-experimental&cookies=yes`,
+      url: `${TEST_BASE_URL}/v1/resolve?osdk=web-0.0.0-experimental&sid=0&cookies=yes`,
     });
   });
 });
diff --git a/lib/sdk.test.ts b/lib/sdk.test.ts
index 97fd9c6..af27db9 100644
--- a/lib/sdk.test.ts
+++ b/lib/sdk.test.ts
@@ -202,10 +202,14 @@ describe("Breaking change detection: if typescript complains or a test fails it'
 
 describe("behavior testing of", () => {
   beforeEach(() => {
-    localStorage.clear();
+    jest.spyOn(crypto, "randomUUID").mockReturnValue("0");
     jest.clearAllMocks();
   });
 
+  afterEach(() => {
+    localStorage.clear();
+  });
+
   test("constructor with cookies and initPassport set to false initializes without localStorage", async () => {
     const fetchSpy = jest.spyOn(window, "fetch");
     const sdk = new OptableSDK({
@@ -222,6 +226,7 @@ describe("behavior testing of", () => {
       site: "site",
       cookies: false,
       initPassport: false,
+      sessionID: "0",
     });
     await sdk["init"];
     expect(localStorage.setItem).toBeCalledTimes(0);
@@ -232,7 +237,7 @@ describe("behavior testing of", () => {
       expect.objectContaining({
         method: "POST",
         _bodyText: '["c:a1a335b8216658319f96a4b0c718557ba41dd1f5"]',
-        url: `${TEST_BASE_URL}/identify?osdk=web-0.0.0-experimental&cookies=no&passport=`,
+        url: `${TEST_BASE_URL}/identify?osdk=web-0.0.0-experimental&sid=0&cookies=no&passport=`,
       })
     );
 
@@ -242,7 +247,7 @@ describe("behavior testing of", () => {
       expect.objectContaining({
         method: "POST",
         _bodyText: '["c:a1a335b8216658319f96a4b0c718557ba41dd1f6"]',
-        url: `${TEST_BASE_URL}/identify?osdk=web-0.0.0-experimental&cookies=no&passport=PASSPORT`,
+        url: `${TEST_BASE_URL}/identify?osdk=web-0.0.0-experimental&sid=0&cookies=no&passport=PASSPORT`,
       })
     );
   });
@@ -259,6 +264,7 @@ describe("behavior testing of", () => {
       site: "site",
       cookies: true,
       initPassport: true,
+      sessionID: "0",
     });
     await sdk["init"];
     expect(window.localStorage.setItem).toHaveBeenLastCalledWith(
@@ -270,7 +276,7 @@ describe("behavior testing of", () => {
       expect.objectContaining({
         method: "GET",
         bodyUsed: false,
-        url: expect.stringContaining("config?osdk=web-0.0.0-experimental&cookies=yes"),
+        url: expect.stringContaining("config?osdk=web-0.0.0-experimental&sid=0&cookies=yes"),
       })
     );
 
@@ -280,7 +286,7 @@ describe("behavior testing of", () => {
       expect.objectContaining({
         method: "POST",
         _bodyText: '["c:a1a335b8216658319f96a4b0c718557ba41dd1f5"]',
-        url: `${TEST_BASE_URL}/identify?osdk=web-0.0.0-experimental&cookies=yes`,
+        url: `${TEST_BASE_URL}/identify?osdk=web-0.0.0-experimental&sid=0&cookies=yes`,
       })
     );
   });
diff --git a/setup-jest.js b/setup-jest.js
index ad4b574..f633d7d 100644
--- a/setup-jest.js
+++ b/setup-jest.js
@@ -2,7 +2,12 @@ import "whatwg-fetch";
 import { TextEncoder } from "node:util";
 import { TransformStream } from "node:stream/web";
 import { BroadcastChannel } from "node:worker_threads";
+import { webcrypto } from 'node:crypto';
 
 global.TextEncoder = TextEncoder;
 global.TransformStream = TransformStream;
 global.BroadcastChannel = BroadcastChannel;
+
+Object.defineProperty(globalThis, 'crypto', {
+  value: webcrypto,
+});