diff --git a/package.json b/package.json
index c520dd0..e9bb106 100644
--- a/package.json
+++ b/package.json
@@ -49,8 +49,7 @@
   },
   "dependencies": {
     "base64-js": "^1.3.0",
-    "fast-deep-equal": "^2.0.1",
-    "uuid": "^8.0.0"
+    "fast-deep-equal": "^2.0.1"
   },
   "repository": {
     "type": "git",
diff --git a/src/AnonymousContextProcessor.js b/src/AnonymousContextProcessor.js
index 8223b5c..ddff8ec 100644
--- a/src/AnonymousContextProcessor.js
+++ b/src/AnonymousContextProcessor.js
@@ -1,4 +1,4 @@
-const { v1: uuidv1 } = require('uuid');
+const { randomUuidV4 } = require('./uuid');
 const { getContextKinds } = require('./context');
 
 const errors = require('./errors');
@@ -57,7 +57,7 @@ function AnonymousContextProcessor(persistentStorage) {
           context.key = cachedId;
           return context;
         } else {
-          const id = uuidv1();
+          const id = randomUuidV4();
           context.key = id;
           return setCachedContextKey(id, kind).then(() => context);
         }
diff --git a/src/EventSender.js b/src/EventSender.js
index 5a9a620..b295d4b 100644
--- a/src/EventSender.js
+++ b/src/EventSender.js
@@ -1,6 +1,6 @@
 const errors = require('./errors');
 const utils = require('./utils');
-const { v1: uuidv1 } = require('uuid');
+const { randomUuidV4 } = require('./uuid');
 const { getLDHeaders, transformHeaders } = require('./headers');
 
 function EventSender(platform, environmentId, options) {
@@ -25,7 +25,7 @@ function EventSender(platform, environmentId, options) {
     }
 
     const jsonBody = JSON.stringify(events);
-    const payloadId = isDiagnostic ? null : uuidv1();
+    const payloadId = isDiagnostic ? null : randomUuidV4();
 
     function doPostRequest(canRetry) {
       const headers = isDiagnostic
diff --git a/src/__tests__/diagnosticEvents-test.js b/src/__tests__/diagnosticEvents-test.js
index e38d32c..7186538 100644
--- a/src/__tests__/diagnosticEvents-test.js
+++ b/src/__tests__/diagnosticEvents-test.js
@@ -16,6 +16,12 @@ describe('DiagnosticId', () => {
     expect(id1.diagnosticId).not.toEqual(id2.diagnosticId);
   });
 
+  it('generates valid UUID v4 format', () => {
+    const id = DiagnosticId('key');
+    const uuidV4Regex = /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
+    expect(id.diagnosticId).toMatch(uuidV4Regex);
+  });
+
   it('uses only last 6 characters of key', () => {
     const id = DiagnosticId('0123456789abcdef');
     expect(id.sdkKeySuffix).toEqual('abcdef');
diff --git a/src/diagnosticEvents.js b/src/diagnosticEvents.js
index 4d7ad19..f5949e3 100644
--- a/src/diagnosticEvents.js
+++ b/src/diagnosticEvents.js
@@ -1,7 +1,4 @@
-const { v1: uuidv1 } = require('uuid');
-// Note that in the diagnostic events spec, these IDs are to be generated with UUID v4. However,
-// in JS we were already using v1 for unique context keys, so to avoid bringing in two packages we
-// will use v1 here as well.
+const { randomUuidV4 } = require('./uuid');
 
 const { baseOptionDefs } = require('./configuration');
 const messages = require('./messages');
@@ -9,7 +6,7 @@ const { appendUrlPath } = require('./utils');
 
 function DiagnosticId(sdkKey) {
   const ret = {
-    diagnosticId: uuidv1(),
+    diagnosticId: randomUuidV4(),
   };
   if (sdkKey) {
     ret.sdkKeySuffix = sdkKey.length > 6 ? sdkKey.substring(sdkKey.length - 6) : sdkKey;
diff --git a/src/uuid.js b/src/uuid.js
new file mode 100644
index 0000000..821b80c
--- /dev/null
+++ b/src/uuid.js
@@ -0,0 +1,70 @@
+/* global crypto */
+// The implementation in this file generates UUIDs in v4 format and is suitable
+// for use as a UUID in LaunchDarkly events. It is not a rigorous implementation.
+//
+// Adapted from:
+// https://github.com/launchdarkly/js-core/blob/main/packages/sdk/browser/src/platform/randomUuidV4.ts
+
+// It uses crypto.randomUUID when available.
+// If crypto.randomUUID is not available, then it uses random values and forms
+// the UUID itself.
+// When possible it uses crypto.getRandomValues, but it can use Math.random
+// if crypto.getRandomValues is not available.
+
+// UUIDv4 Struct definition.
+// https://www.rfc-archive.org/getrfc.php?rfc=4122
+// Appendix A.  Appendix A - Sample Implementation
+const timeLow = { start: 0, end: 3 };
+const timeMid = { start: 4, end: 5 };
+const timeHiAndVersion = { start: 6, end: 7 };
+const clockSeqHiAndReserved = { start: 8, end: 8 };
+const clockSeqLow = { start: 9, end: 9 };
+const nodes = { start: 10, end: 15 };
+
+function getRandom128bit() {
+  if (typeof crypto !== 'undefined' && crypto.getRandomValues) {
+    const typedArray = new Uint8Array(16);
+    crypto.getRandomValues(typedArray);
+    return [...typedArray.values()];
+  }
+  const values = [];
+  for (let index = 0; index < 16; index += 1) {
+    values.push(Math.floor(Math.random() * 256));
+  }
+  return values;
+}
+
+function hex(bytes, range) {
+  let strVal = '';
+  for (let index = range.start; index <= range.end; index += 1) {
+    strVal += bytes[index].toString(16).padStart(2, '0');
+  }
+  return strVal;
+}
+
+function formatDataAsUuidV4(bytes) {
+  // eslint-disable-next-line no-bitwise, no-param-reassign
+  bytes[clockSeqHiAndReserved.start] = (bytes[clockSeqHiAndReserved.start] | 0x80) & 0xbf;
+  // eslint-disable-next-line no-bitwise, no-param-reassign
+  bytes[timeHiAndVersion.start] = (bytes[timeHiAndVersion.start] & 0x0f) | 0x40;
+
+  return (
+    `${hex(bytes, timeLow)}-${hex(bytes, timeMid)}-${hex(bytes, timeHiAndVersion)}-` +
+    `${hex(bytes, clockSeqHiAndReserved)}${hex(bytes, clockSeqLow)}-${hex(bytes, nodes)}`
+  );
+}
+
+function fallbackUuidV4() {
+  const bytes = getRandom128bit();
+  return formatDataAsUuidV4(bytes);
+}
+
+function randomUuidV4() {
+  if (typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function') {
+    return crypto.randomUUID();
+  }
+
+  return fallbackUuidV4();
+}
+
+module.exports = { randomUuidV4, fallbackUuidV4, formatDataAsUuidV4 };