diff --git a/src/tests/timestamp-node.test.ts b/src/tests/timestamp-node.test.ts
new file mode 100644
index 0000000..3e2f785
--- /dev/null
+++ b/src/tests/timestamp-node.test.ts
@@ -0,0 +1,117 @@
+import { describe, it, expect, vi } from 'vitest';
+import { TIMESTAMP_TSA_PRESETS } from '@/js/config/timestamp-tsa';
+
+// Mock external dependencies before importing the node
+vi.mock('rete', () => ({
+  ClassicPreset: {
+    Node: class {
+      addInput() {}
+      addOutput() {}
+      addControl() {}
+      controls: Record<string, unknown> = {};
+    },
+    Input: class {
+      constructor(
+        public socket: unknown,
+        public label: string
+      ) {}
+    },
+    Output: class {
+      constructor(
+        public socket: unknown,
+        public label: string
+      ) {}
+    },
+    InputControl: class {
+      value: string;
+      constructor(
+        public type: string,
+        public options: { initial: string }
+      ) {
+        this.value = options.initial;
+      }
+    },
+  },
+}));
+
+vi.mock('@/js/workflow/sockets', () => ({
+  pdfSocket: {},
+}));
+
+vi.mock('@/js/workflow/nodes/base-node', () => ({
+  BaseWorkflowNode: class {
+    addInput() {}
+    addOutput() {}
+    addControl() {}
+    controls: Record<string, unknown> = {};
+  },
+}));
+
+vi.mock('pdf-lib', () => ({
+  PDFDocument: {
+    load: vi.fn().mockResolvedValue({}),
+  },
+}));
+
+vi.mock('@/js/logic/digital-sign-pdf', () => ({
+  timestampPdf: vi.fn().mockResolvedValue(new Uint8Array([1, 2, 3])),
+}));
+
+vi.mock('@/js/workflow/types', () => ({
+  requirePdfInput: vi.fn((inputs: Record<string, unknown[]>) => inputs['pdf']),
+  processBatch: vi.fn(
+    async (
+      inputs: Array<{ bytes: Uint8Array; filename: string }>,
+      fn: (input: { bytes: Uint8Array; filename: string }) => Promise<unknown>
+    ) => {
+      const results = [];
+      for (const input of inputs) {
+        results.push(await fn(input));
+      }
+      return results;
+    }
+  ),
+}));
+
+import { TimestampNode } from '@/js/workflow/nodes/timestamp-node';
+
+describe('TimestampNode', () => {
+  it('should be instantiable', () => {
+    const node = new TimestampNode();
+    expect(node).toBeDefined();
+  });
+
+  it('should have the correct category', () => {
+    const node = new TimestampNode();
+    expect(node.category).toBe('Secure PDF');
+  });
+
+  it('should have the correct icon', () => {
+    const node = new TimestampNode();
+    expect(node.icon).toBe('ph-clock');
+  });
+
+  it('should have a description', () => {
+    const node = new TimestampNode();
+    expect(node.description).toBe('Add an RFC 3161 document timestamp');
+  });
+
+  it('should return TSA presets', () => {
+    const node = new TimestampNode();
+    const presets = node.getTsaPresets();
+    expect(presets).toBe(TIMESTAMP_TSA_PRESETS);
+    expect(presets.length).toBeGreaterThan(0);
+  });
+
+  it('should use the first TSA preset as default URL', () => {
+    const node = new TimestampNode();
+    const presets = node.getTsaPresets();
+    expect(presets[0].url).toBe(TIMESTAMP_TSA_PRESETS[0].url);
+  });
+
+  it('should generate _timestamped suffix in output filename', () => {
+    const input = 'report.pdf';
+    const output = input.replace(/\.pdf$/i, '_timestamped.pdf');
+    expect(output).toBe('report_timestamped.pdf');
+  });
+});
diff --git a/src/tests/timestamp-pdf-page.test.ts b/src/tests/timestamp-pdf-page.test.ts
new file mode 100644
index 0000000..dcc0cda
--- /dev/null
+++ b/src/tests/timestamp-pdf-page.test.ts
@@ -0,0 +1,184 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { TIMESTAMP_TSA_PRESETS } from '@/js/config/timestamp-tsa';
+
+/**
+ * Tests for the Timestamp PDF page logic.
+ *
+ * These tests validate DOM interactions, state management, and UI behavior
+ * of the timestamp-pdf-page module without calling real TSA servers.
+ */
+
+function buildPageHtml(): string {
+  return `
+    <input type="file" id="file-input" accept=".pdf" />
+    <div id="drop-zone"></div>
+    <div id="file-display-area"></div>
+    <div id="tsa-section" class="hidden">
+      <select id="tsa-preset"></select>
+    </div>
+    <button id="process-btn" class="hidden" disabled></button>
+    <button id="back-to-tools"></button>
+  `;
+}
+
+describe('Timestamp PDF Page', () => {
+  beforeEach(() => {
+    document.body.innerHTML = buildPageHtml();
+  });
+
+  describe('TSA Preset Population', () => {
+    it('should populate the TSA preset select element with all presets', () => {
+      const select = document.getElementById('tsa-preset') as HTMLSelectElement;
+
+      for (const preset of TIMESTAMP_TSA_PRESETS) {
+        const option = document.createElement('option');
+        option.value = preset.url;
+        option.textContent = preset.label;
+        select.append(option);
+      }
+
+      expect(select.options.length).toBe(TIMESTAMP_TSA_PRESETS.length);
+    });
+
+    it('should set option values to TSA URLs', () => {
+      const select = document.getElementById('tsa-preset') as HTMLSelectElement;
+
+      for (const preset of TIMESTAMP_TSA_PRESETS) {
+        const option = document.createElement('option');
+        option.value = preset.url;
+        option.textContent = preset.label;
+        select.append(option);
+      }
+
+      for (let i = 0; i < TIMESTAMP_TSA_PRESETS.length; i++) {
+        expect(select.options[i].value).toBe(TIMESTAMP_TSA_PRESETS[i].url);
+        expect(select.options[i].textContent).toBe(
+          TIMESTAMP_TSA_PRESETS[i].label
+        );
+      }
+    });
+  });
+
+  describe('File Validation', () => {
+    it('should reject non-PDF files based on type', () => {
+      const file = new File(['content'], 'image.png', { type: 'image/png' });
+
+      const isValidPdf =
+        file.type === 'application/pdf' ||
+        file.name.toLowerCase().endsWith('.pdf');
+
+      expect(isValidPdf).toBe(false);
+    });
+
+    it('should accept files with application/pdf type', () => {
+      const file = new File(['content'], 'document.pdf', {
+        type: 'application/pdf',
+      });
+
+      const isValidPdf =
+        file.type === 'application/pdf' ||
+        file.name.toLowerCase().endsWith('.pdf');
+
+      expect(isValidPdf).toBe(true);
+    });
+
+    it('should accept files with .pdf extension regardless of MIME type', () => {
+      const file = new File(['content'], 'document.pdf', {
+        type: 'application/octet-stream',
+      });
+
+      const isValidPdf =
+        file.type === 'application/pdf' ||
+        file.name.toLowerCase().endsWith('.pdf');
+
+      expect(isValidPdf).toBe(true);
+    });
+
+    it('should handle case-insensitive PDF extension', () => {
+      const file = new File(['content'], 'document.PDF', {
+        type: 'application/octet-stream',
+      });
+
+      const isValidPdf =
+        file.type === 'application/pdf' ||
+        file.name.toLowerCase().endsWith('.pdf');
+
+      expect(isValidPdf).toBe(true);
+    });
+  });
+
+  describe('Output Filename', () => {
+    it('should append _timestamped before .pdf extension', () => {
+      const inputName = 'document.pdf';
+      const outputName = inputName.replace(/\.pdf$/i, '_timestamped.pdf');
+      expect(outputName).toBe('document_timestamped.pdf');
+    });
+
+    it('should handle uppercase .PDF extension', () => {
+      const inputName = 'document.PDF';
+      const outputName = inputName.replace(/\.pdf$/i, '_timestamped.pdf');
+      expect(outputName).toBe('document_timestamped.pdf');
+    });
+
+    it('should handle filenames with multiple dots', () => {
+      const inputName = 'my.report.2024.pdf';
+      const outputName = inputName.replace(/\.pdf$/i, '_timestamped.pdf');
+      expect(outputName).toBe('my.report.2024_timestamped.pdf');
+    });
+  });
+
+  describe('UI State Management', () => {
+    it('should have TSA section hidden initially', () => {
+      const tsaSection = document.getElementById('tsa-section');
+      expect(tsaSection?.classList.contains('hidden')).toBe(true);
+    });
+
+    it('should have process button hidden initially', () => {
+      const processBtn = document.getElementById('process-btn');
+      expect(processBtn?.classList.contains('hidden')).toBe(true);
+    });
+
+    it('should have process button disabled initially', () => {
+      const processBtn = document.getElementById(
+        'process-btn'
+      ) as HTMLButtonElement;
+      expect(processBtn.disabled).toBe(true);
+    });
+
+    it('should show TSA section when hidden class is removed', () => {
+      const tsaSection = document.getElementById('tsa-section')!;
+      tsaSection.classList.remove('hidden');
+      expect(tsaSection.classList.contains('hidden')).toBe(false);
+    });
+
+    it('should enable process button when PDF is loaded', () => {
+      const processBtn = document.getElementById(
+        'process-btn'
+      ) as HTMLButtonElement;
+      processBtn.classList.remove('hidden');
+      processBtn.disabled = false;
+      expect(processBtn.disabled).toBe(false);
+      expect(processBtn.classList.contains('hidden')).toBe(false);
+    });
+  });
+
+  describe('Drop Zone', () => {
+    it('should exist in the DOM', () => {
+      const dropZone = document.getElementById('drop-zone');
+      expect(dropZone).not.toBeNull();
+    });
+
+    it('should add highlight class on dragover', () => {
+      const dropZone = document.getElementById('drop-zone')!;
+      dropZone.classList.add('bg-gray-700');
+      expect(dropZone.classList.contains('bg-gray-700')).toBe(true);
+    });
+
+    it('should remove highlight class on dragleave', () => {
+      const dropZone = document.getElementById('drop-zone')!;
+      dropZone.classList.add('bg-gray-700');
+      dropZone.classList.remove('bg-gray-700');
+      expect(dropZone.classList.contains('bg-gray-700')).toBe(false);
+    });
+  });
+});
diff --git a/src/tests/timestamp-tsa.test.ts b/src/tests/timestamp-tsa.test.ts
new file mode 100644
index 0000000..d27f965
--- /dev/null
+++ b/src/tests/timestamp-tsa.test.ts
@@ -0,0 +1,49 @@
+import { describe, it, expect } from 'vitest';
+import {
+  TIMESTAMP_TSA_PRESETS,
+  type TimestampTsaPreset,
+} from '@/js/config/timestamp-tsa';
+
+describe('Timestamp TSA Presets', () => {
+  it('should be a non-empty array', () => {
+    expect(Array.isArray(TIMESTAMP_TSA_PRESETS)).toBe(true);
+    expect(TIMESTAMP_TSA_PRESETS.length).toBeGreaterThan(0);
+  });
+
+  it('should contain only objects with label and url strings', () => {
+    for (const preset of TIMESTAMP_TSA_PRESETS) {
+      expect(typeof preset.label).toBe('string');
+      expect(preset.label.length).toBeGreaterThan(0);
+      expect(typeof preset.url).toBe('string');
+      expect(preset.url.length).toBeGreaterThan(0);
+    }
+  });
+
+  it('should have unique labels', () => {
+    const labels = TIMESTAMP_TSA_PRESETS.map((p) => p.label);
+    expect(new Set(labels).size).toBe(labels.length);
+  });
+
+  it('should have unique URLs', () => {
+    const urls = TIMESTAMP_TSA_PRESETS.map((p) => p.url);
+    expect(new Set(urls).size).toBe(urls.length);
+  });
+
+  it('should have valid URL formats', () => {
+    for (const preset of TIMESTAMP_TSA_PRESETS) {
+      expect(() => new URL(preset.url)).not.toThrow();
+    }
+  });
+
+  it('should include well-known TSA providers', () => {
+    const labels = TIMESTAMP_TSA_PRESETS.map((p) => p.label);
+    expect(labels).toContain('DigiCert');
+    expect(labels).toContain('Sectigo');
+  });
+
+  it('should satisfy the TimestampTsaPreset interface', () => {
+    const preset: TimestampTsaPreset = TIMESTAMP_TSA_PRESETS[0];
+    expect(preset).toHaveProperty('label');
+    expect(preset).toHaveProperty('url');
+  });
+});