diff --git a/frontend/src/utils/date.js b/frontend/src/utils/date.js
new file mode 100644
index 0000000..f0ade54
--- /dev/null
+++ b/frontend/src/utils/date.js
@@ -0,0 +1,15 @@
+// Locale-independent post-date formatting. Uses a fixed month table and
+// UTC getters so the rendered string never varies by browser/CI locale
+// or timezone (toLocaleDateString would make tests flaky).
+
+const MONTHS = [
+  'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
+  'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
+]
+
+export function formatPostDate(iso) {
+  if (!iso) return null
+  const d = new Date(iso)
+  if (isNaN(d.getTime())) return null
+  return `${MONTHS[d.getUTCMonth()]} ${d.getUTCDate()}, ${d.getUTCFullYear()}`
+}
diff --git a/frontend/test/date.spec.js b/frontend/test/date.spec.js
new file mode 100644
index 0000000..60415b5
--- /dev/null
+++ b/frontend/test/date.spec.js
@@ -0,0 +1,15 @@
+import { describe, it, expect } from 'vitest'
+import { formatPostDate } from '../src/utils/date.js'
+
+describe('formatPostDate', () => {
+  it('formats an ISO datetime as "Mon D, YYYY" in UTC', () => {
+    expect(formatPostDate('2023-08-01T00:00:00+00:00')).toBe('Aug 1, 2023')
+    expect(formatPostDate('2023-12-25T23:59:59Z')).toBe('Dec 25, 2023')
+  })
+
+  it('returns null for null/empty/invalid', () => {
+    expect(formatPostDate(null)).toBe(null)
+    expect(formatPostDate('')).toBe(null)
+    expect(formatPostDate('not-a-date')).toBe(null)
+  })
+})