diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index 66f1fca2..bfb2e940 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -3,3 +3,5 @@ export type { RandomGenerator } from './utils/random';
 export { HawkUserManager } from './users/hawk-user-manager';
 export type { Logger, LogType } from './logger/logger';
 export { isLoggerSet, setLogger, resetLogger, log } from './logger/logger';
+export { validateUser, validateContext, isValidEventPayload, isValidBreadcrumb } from './utils/validation';
+export { isPlainObject } from './utils/type-guards';
diff --git a/packages/core/src/utils/type-guards.ts b/packages/core/src/utils/type-guards.ts
new file mode 100644
index 00000000..3375ee02
--- /dev/null
+++ b/packages/core/src/utils/type-guards.ts
@@ -0,0 +1,14 @@
+/**
+ * Checks if value is a plain object (not null, array, Date, Map, etc.)
+ *
+ * @param value - value to check
+ * @returns `true` if value is a plain object, otherwise `false`
+ */
+export function isPlainObject(value: unknown): value is Record<string, unknown> {
+  if (typeof value !== 'object' || value === null) {
+    return false;
+  }
+  const proto = Object.getPrototypeOf(value);
+
+  return proto === Object.prototype || proto === null;
+}
diff --git a/packages/javascript/src/utils/validation.ts b/packages/core/src/utils/validation.ts
similarity index 64%
rename from packages/javascript/src/utils/validation.ts
rename to packages/core/src/utils/validation.ts
index 293cafc6..e00c3865 100644
--- a/packages/javascript/src/utils/validation.ts
+++ b/packages/core/src/utils/validation.ts
@@ -1,6 +1,6 @@
-import { log } from '@hawk.so/core';
-import type { AffectedUser, Breadcrumb, EventContext, EventData, JavaScriptAddons } from '@hawk.so/types';
-import Sanitizer from '../modules/sanitizer';
+import { log } from '../logger/logger';
+import type { AffectedUser, Breadcrumb, EventAddons, EventContext, EventData } from '@hawk.so/types';
+import { isPlainObject } from './type-guards';
 
 /**
  * Validates user data - basic security checks
@@ -8,7 +8,7 @@ import Sanitizer from '../modules/sanitizer';
  * @param user - user data to validate
  */
 export function validateUser(user: AffectedUser): boolean {
-  if (!user || !Sanitizer.isObject(user)) {
+  if (!user || !isPlainObject(user)) {
     log('validateUser: User must be an object', 'warn');
 
     return false;
@@ -30,7 +30,7 @@ export function validateUser(user: AffectedUser): boolean {
  * @param context - context data to validate
  */
 export function validateContext(context: EventContext | undefined): boolean {
-  if (context && !Sanitizer.isObject(context)) {
+  if (context && !isPlainObject(context)) {
     log('validateContext: Context must be an object', 'warn');
 
     return false;
@@ -39,23 +39,14 @@ export function validateContext(context: EventContext | undefined): boolean {
   return true;
 }
 
-/**
- * Checks if value is a plain object (not array, Date, etc.)
- *
- * @param value - value to check
- */
-function isPlainObject(value: unknown): value is Record<string, unknown> {
-  return Object.prototype.toString.call(value) === '[object Object]';
-}
-
 /**
  * Runtime check for required EventData fields.
  * Per @hawk.so/types EventData, `title` is the only non-optional field.
- * Additionally validates `backtrace` shape if present (must be an array).
+ * Additionally, validates `backtrace` shape if present (must be an array).
  *
  * @param payload - value to validate
  */
-export function isValidEventPayload(payload: unknown): payload is EventData<JavaScriptAddons> {
+export function isValidEventPayload(payload: unknown): payload is EventData<EventAddons> {
   if (!isPlainObject(payload)) {
     return false;
   }
@@ -64,11 +55,10 @@ export function isValidEventPayload(payload: unknown): payload is EventData<Java
     return false;
   }
 
-  if (payload.backtrace !== undefined && !Array.isArray(payload.backtrace)) {
-    return false;
-  }
+  const isBacktraceUndefined = payload.backtrace === undefined;
+  const isBacktraceArray = Array.isArray(payload.backtrace);
 
-  return true;
+  return isBacktraceUndefined || isBacktraceArray;
 }
 
 /**
@@ -86,9 +76,8 @@ export function isValidBreadcrumb(breadcrumb: unknown): breadcrumb is Breadcrumb
     return false;
   }
 
-  if (breadcrumb.timestamp !== undefined && typeof breadcrumb.timestamp !== 'number') {
-    return false;
-  }
+  const isTimestampUndefined = breadcrumb.timestamp === undefined;
+  const isTimestampNumber = typeof breadcrumb.timestamp === 'number';
 
-  return true;
+  return isTimestampUndefined || isTimestampNumber;
 }
diff --git a/packages/core/tests/utils/type-guards.test.ts b/packages/core/tests/utils/type-guards.test.ts
new file mode 100644
index 00000000..ecf490f4
--- /dev/null
+++ b/packages/core/tests/utils/type-guards.test.ts
@@ -0,0 +1,18 @@
+import { describe, expect, it } from 'vitest';
+import { isPlainObject } from '../../src';
+
+class Foo {}
+const fooInstance = new Foo();
+
+describe('isPlainObject', () => {
+  it('should return true for plain object', () => expect(isPlainObject({})).toBe(true));
+  it('should return true for plain object with properties', () => expect(isPlainObject({ a: 1 })).toBe(true));
+  it('should return false for array', () => expect(isPlainObject([])).toBe(false));
+  it('should return false for string', () => expect(isPlainObject('x')).toBe(false));
+  it('should return false for number', () => expect(isPlainObject(42)).toBe(false));
+  it('should return false for boolean', () => expect(isPlainObject(true)).toBe(false));
+  it('should return false for null', () => expect(isPlainObject(null)).toBe(false));
+  it('should return false for undefined', () => expect(isPlainObject(undefined)).toBe(false));
+  it('should return false for class prototype', () => expect(isPlainObject(Foo)).toBe(false));
+  it('should return false for class instance', () => expect(isPlainObject(fooInstance)).toBe(false));
+});
diff --git a/packages/javascript/tests/utils/validation.test.ts b/packages/core/tests/utils/validation.test.ts
similarity index 92%
rename from packages/javascript/tests/utils/validation.test.ts
rename to packages/core/tests/utils/validation.test.ts
index 20d02944..bb2a16c2 100644
--- a/packages/javascript/tests/utils/validation.test.ts
+++ b/packages/core/tests/utils/validation.test.ts
@@ -1,8 +1,8 @@
-import { describe, it, expect, vi } from 'vitest';
-import { validateUser, validateContext, isValidEventPayload, isValidBreadcrumb } from '../../src/utils/validation';
+import { describe, expect, it, vi } from 'vitest';
+import { isValidBreadcrumb, isValidEventPayload, validateContext, validateUser } from '../../src';
 
 // Suppress log output produced by log() calls inside validation failures.
-vi.mock('@hawk.so/core', () => ({ log: vi.fn(), isLoggerSet: vi.fn(() => true), setLogger: vi.fn() }));
+vi.mock('../../src/logger/logger', () => ({ log: vi.fn(), isLoggerSet: vi.fn(() => true), setLogger: vi.fn() }));
 
 describe('validateUser', () => {
   it('should return false when user is null', () => {
diff --git a/packages/javascript/src/addons/breadcrumbs.ts b/packages/javascript/src/addons/breadcrumbs.ts
index 1e4f0b9b..89ef2e23 100644
--- a/packages/javascript/src/addons/breadcrumbs.ts
+++ b/packages/javascript/src/addons/breadcrumbs.ts
@@ -4,8 +4,7 @@
 import type { Breadcrumb, BreadcrumbLevel, BreadcrumbType, Json, JsonNode } from '@hawk.so/types';
 import Sanitizer from '../modules/sanitizer';
 import { buildElementSelector } from '../utils/selector';
-import { log } from '@hawk.so/core';
-import { isValidBreadcrumb } from '../utils/validation';
+import { isValidBreadcrumb, log } from '@hawk.so/core';
 
 /**
  * Default maximum number of breadcrumbs to store
diff --git a/packages/javascript/src/catcher.ts b/packages/javascript/src/catcher.ts
index 822d974c..5bf07dd1 100644
--- a/packages/javascript/src/catcher.ts
+++ b/packages/javascript/src/catcher.ts
@@ -18,7 +18,7 @@ import { isErrorProcessed, markErrorAsProcessed } from './utils/event';
 import { BrowserRandomGenerator } from './utils/random';
 import { ConsoleCatcher } from './addons/consoleCatcher';
 import { BreadcrumbManager } from './addons/breadcrumbs';
-import { isValidEventPayload, validateContext, validateUser } from './utils/validation';
+import { isValidEventPayload, validateContext, validateUser } from '@hawk.so/core';
 import { HawkUserManager, isLoggerSet, log, setLogger } from '@hawk.so/core';
 import { HawkLocalStorage } from './storages/hawk-local-storage';
 import { createBrowserLogger } from './logger/logger';