diff --git a/src/lib/validators.test.ts b/src/lib/validators.test.ts
new file mode 100644
index 0000000..d89093a
--- /dev/null
+++ b/src/lib/validators.test.ts
@@ -0,0 +1,320 @@
+import { describe, it, expect } from 'vitest';
+import type { NostrEvent } from '@nostrify/nostrify';
+import {
+  validateHighlight,
+  getHighlightSource,
+  getHighlightComment,
+  getHighlightContext,
+  getHighlightAuthors,
+  isQuoteHighlight,
+  cleanUrl,
+} from './validators';
+
+describe('validateHighlight', () => {
+  it('validates a basic highlight with e tag', () => {
+    const event: NostrEvent = {
+      id: 'test-id',
+      pubkey: 'test-pubkey',
+      created_at: 1234567890,
+      kind: 9802,
+      tags: [
+        ['e', 'event-id'],
+        ['p', 'author-pubkey', '', 'author'],
+      ],
+      content: 'This is a highlighted passage',
+      sig: 'test-sig',
+    };
+
+    expect(validateHighlight(event)).toBe(true);
+  });
+
+  it('validates a highlight with a tag', () => {
+    const event: NostrEvent = {
+      id: 'test-id',
+      pubkey: 'test-pubkey',
+      created_at: 1234567890,
+      kind: 9802,
+      tags: [
+        ['a', '30023:author-pubkey:identifier'],
+        ['p', 'author-pubkey', '', 'author'],
+      ],
+      content: 'This is a highlighted passage',
+      sig: 'test-sig',
+    };
+
+    expect(validateHighlight(event)).toBe(true);
+  });
+
+  it('validates a highlight with r tag', () => {
+    const event: NostrEvent = {
+      id: 'test-id',
+      pubkey: 'test-pubkey',
+      created_at: 1234567890,
+      kind: 9802,
+      tags: [
+        ['r', 'https://example.com/article'],
+      ],
+      content: 'This is a highlighted passage',
+      sig: 'test-sig',
+    };
+
+    expect(validateHighlight(event)).toBe(true);
+  });
+
+  it('rejects events that are not kind 9802', () => {
+    const event: NostrEvent = {
+      id: 'test-id',
+      pubkey: 'test-pubkey',
+      created_at: 1234567890,
+      kind: 1,
+      tags: [['e', 'event-id']],
+      content: 'This is a note',
+      sig: 'test-sig',
+    };
+
+    expect(validateHighlight(event)).toBe(false);
+  });
+
+  it('rejects highlights without reference tags', () => {
+    const event: NostrEvent = {
+      id: 'test-id',
+      pubkey: 'test-pubkey',
+      created_at: 1234567890,
+      kind: 9802,
+      tags: [
+        ['p', 'author-pubkey', '', 'author'],
+      ],
+      content: 'This is a highlighted passage',
+      sig: 'test-sig',
+    };
+
+    expect(validateHighlight(event)).toBe(false);
+  });
+
+  it('allows empty content for non-text media', () => {
+    const event: NostrEvent = {
+      id: 'test-id',
+      pubkey: 'test-pubkey',
+      created_at: 1234567890,
+      kind: 9802,
+      tags: [['e', 'event-id']],
+      content: '',
+      sig: 'test-sig',
+    };
+
+    expect(validateHighlight(event)).toBe(true);
+  });
+});
+
+describe('getHighlightSource', () => {
+  it('extracts address source from a tag', () => {
+    const event = {
+      kind: 9802,
+      tags: [['a', '30023:pubkey:identifier']],
+    } as never;
+
+    const source = getHighlightSource(event);
+    expect(source).toEqual({
+      type: 'address',
+      value: '30023:pubkey:identifier',
+    });
+  });
+
+  it('extracts event source from e tag', () => {
+    const event = {
+      kind: 9802,
+      tags: [['e', 'event-id']],
+    } as never;
+
+    const source = getHighlightSource(event);
+    expect(source).toEqual({
+      type: 'event',
+      value: 'event-id',
+    });
+  });
+
+  it('extracts URL source from r tag', () => {
+    const event = {
+      kind: 9802,
+      tags: [['r', 'https://example.com/article']],
+    } as never;
+
+    const source = getHighlightSource(event);
+    expect(source).toEqual({
+      type: 'url',
+      value: 'https://example.com/article',
+    });
+  });
+
+  it('prioritizes a tag over e and r tags', () => {
+    const event = {
+      kind: 9802,
+      tags: [
+        ['a', '30023:pubkey:identifier'],
+        ['e', 'event-id'],
+        ['r', 'https://example.com'],
+      ],
+    } as never;
+
+    const source = getHighlightSource(event);
+    expect(source?.type).toBe('address');
+  });
+
+  it('returns null when no reference tags exist', () => {
+    const event = {
+      kind: 9802,
+      tags: [['p', 'author-pubkey']],
+    } as never;
+
+    const source = getHighlightSource(event);
+    expect(source).toBeNull();
+  });
+});
+
+describe('getHighlightComment', () => {
+  it('extracts comment from quote highlight', () => {
+    const event = {
+      kind: 9802,
+      tags: [
+        ['e', 'event-id'],
+        ['comment', 'This is my commentary'],
+      ],
+    } as never;
+
+    expect(getHighlightComment(event)).toBe('This is my commentary');
+  });
+
+  it('returns null when no comment exists', () => {
+    const event = {
+      kind: 9802,
+      tags: [['e', 'event-id']],
+    } as never;
+
+    expect(getHighlightComment(event)).toBeNull();
+  });
+});
+
+describe('getHighlightContext', () => {
+  it('extracts context text', () => {
+    const event = {
+      kind: 9802,
+      tags: [
+        ['e', 'event-id'],
+        ['context', 'This is the surrounding paragraph text'],
+      ],
+    } as never;
+
+    expect(getHighlightContext(event)).toBe('This is the surrounding paragraph text');
+  });
+
+  it('returns null when no context exists', () => {
+    const event = {
+      kind: 9802,
+      tags: [['e', 'event-id']],
+    } as never;
+
+    expect(getHighlightContext(event)).toBeNull();
+  });
+});
+
+describe('getHighlightAuthors', () => {
+  it('extracts all author pubkeys', () => {
+    const event = {
+      kind: 9802,
+      tags: [
+        ['e', 'event-id'],
+        ['p', 'author1', '', 'author'],
+        ['p', 'author2', '', 'author'],
+        ['p', 'mentioned', '', 'mention'],
+      ],
+    } as never;
+
+    const authors = getHighlightAuthors(event);
+    expect(authors).toEqual(['author1', 'author2']);
+  });
+
+  it('returns empty array when no authors exist', () => {
+    const event = {
+      kind: 9802,
+      tags: [['e', 'event-id']],
+    } as never;
+
+    const authors = getHighlightAuthors(event);
+    expect(authors).toEqual([]);
+  });
+
+  it('filters out mentions and only includes authors', () => {
+    const event = {
+      kind: 9802,
+      tags: [
+        ['p', 'author', '', 'author'],
+        ['p', 'mention', '', 'mention'],
+        ['p', 'editor', '', 'editor'],
+      ],
+    } as never;
+
+    const authors = getHighlightAuthors(event);
+    expect(authors).toEqual(['author']);
+  });
+});
+
+describe('isQuoteHighlight', () => {
+  it('returns true for highlights with comment tag', () => {
+    const event = {
+      kind: 9802,
+      tags: [
+        ['e', 'event-id'],
+        ['comment', 'My thoughts'],
+      ],
+    } as never;
+
+    expect(isQuoteHighlight(event)).toBe(true);
+  });
+
+  it('returns false for highlights without comment tag', () => {
+    const event = {
+      kind: 9802,
+      tags: [['e', 'event-id']],
+    } as never;
+
+    expect(isQuoteHighlight(event)).toBe(false);
+  });
+});
+
+describe('cleanUrl', () => {
+  it('removes UTM parameters', () => {
+    const url = 'https://example.com/article?utm_source=twitter&utm_medium=social&utm_campaign=spring';
+    const cleaned = cleanUrl(url);
+    expect(cleaned).toBe('https://example.com/article');
+  });
+
+  it('removes tracking parameters', () => {
+    const url = 'https://example.com/article?fbclid=abc123&gclid=xyz789';
+    const cleaned = cleanUrl(url);
+    expect(cleaned).toBe('https://example.com/article');
+  });
+
+  it('preserves non-tracking parameters', () => {
+    const url = 'https://example.com/article?page=2&sort=date';
+    const cleaned = cleanUrl(url);
+    expect(cleaned).toBe('https://example.com/article?page=2&sort=date');
+  });
+
+  it('handles URLs with mixed parameters', () => {
+    const url = 'https://example.com/article?page=2&utm_source=twitter&sort=date';
+    const cleaned = cleanUrl(url);
+    expect(cleaned).toBe('https://example.com/article?page=2&sort=date');
+  });
+
+  it('handles URLs without query parameters', () => {
+    const url = 'https://example.com/article';
+    const cleaned = cleanUrl(url);
+    expect(cleaned).toBe('https://example.com/article');
+  });
+
+  it('returns original URL when parsing fails', () => {
+    const url = 'not-a-valid-url';
+    const cleaned = cleanUrl(url);
+    expect(cleaned).toBe('not-a-valid-url');
+  });
+});