diff --git a/snapshot/src/core/dedup.ts b/snapshot/src/core/dedup.ts
new file mode 100644
index 0000000..8c19983
--- /dev/null
+++ b/snapshot/src/core/dedup.ts
@@ -0,0 +1,14 @@
+import type { SignedEvent } from './types.ts'
+
+export function dedupByDtag(events: SignedEvent[]): SignedEvent[] {
+  const byDtag = new Map<string, SignedEvent>()
+  for (const ev of events) {
+    const d = ev.tags.find((t) => t[0] === 'd')?.[1]
+    if (!d) continue
+    const existing = byDtag.get(d)
+    if (!existing || ev.created_at > existing.created_at) {
+      byDtag.set(d, ev)
+    }
+  }
+  return [...byDtag.values()]
+}
diff --git a/snapshot/src/core/types.ts b/snapshot/src/core/types.ts
new file mode 100644
index 0000000..7f338c7
--- /dev/null
+++ b/snapshot/src/core/types.ts
@@ -0,0 +1,9 @@
+export interface SignedEvent {
+  id: string
+  pubkey: string
+  created_at: number
+  kind: number
+  tags: string[][]
+  content: string
+  sig: string
+}
diff --git a/snapshot/tests/dedup.test.ts b/snapshot/tests/dedup.test.ts
new file mode 100644
index 0000000..726cc4d
--- /dev/null
+++ b/snapshot/tests/dedup.test.ts
@@ -0,0 +1,29 @@
+import { assertEquals } from '@std/assert'
+import { dedupByDtag } from '../src/core/dedup.ts'
+import type { SignedEvent } from '../src/core/types.ts'
+
+function ev(d: string, created_at: number, id: string): SignedEvent {
+  return {
+    id, pubkey: 'p', created_at, kind: 30023, sig: 's', content: '',
+    tags: [['d', d]],
+  }
+}
+
+Deno.test('dedupByDtag behaelt das neueste event pro d-tag', () => {
+  const out = dedupByDtag([
+    ev('a', 100, 'a-old'),
+    ev('a', 200, 'a-new'),
+    ev('b', 50, 'b-only'),
+  ])
+  const ids = out.map((e) => e.id).sort()
+  assertEquals(ids, ['a-new', 'b-only'])
+})
+
+Deno.test('dedupByDtag laesst events ohne d-tag weg', () => {
+  const out = dedupByDtag([
+    { id: 'x', pubkey: 'p', created_at: 1, kind: 30023, sig: 's', content: '', tags: [] },
+    ev('a', 1, 'a'),
+  ])
+  assertEquals(out.length, 1)
+  assertEquals(out[0].id, 'a')
+})