diff --git a/src/lib/rss.ts b/src/lib/rss.ts
new file mode 100644
index 0000000..7c092f5
--- /dev/null
+++ b/src/lib/rss.ts
@@ -0,0 +1,39 @@
+function esc(s: string) {
+  return s.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;')
+}
+
+export type RssItem = {
+  title: string
+  url: string
+  description?: string
+  publishDate: Date
+}
+
+export function buildRss(opts: {
+  title: string
+  description: string
+  siteUrl: string
+  items: RssItem[]
+}) {
+  const items = opts.items
+    .map(
+      (i) => `
+    <item>
+      <title>${esc(i.title)}</title>
+      <link>${esc(opts.siteUrl + i.url)}</link>
+      <guid>${esc(opts.siteUrl + i.url)}</guid>
+      <pubDate>${i.publishDate.toUTCString()}</pubDate>
+      ${i.description ? `<description>${esc(i.description)}</description>` : ''}
+    </item>`,
+    )
+    .join('')
+  return `<?xml version="1.0" encoding="UTF-8"?>
+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+    <title>${esc(opts.title)}</title>
+    <link>${esc(opts.siteUrl)}</link>
+    <description>${esc(opts.description)}</description>
+    <atom:link href="${esc(opts.siteUrl)}/rss.xml" rel="self" type="application/rss+xml" />${items}
+  </channel>
+</rss>`
+}
diff --git a/tests/int/rss.int.spec.ts b/tests/int/rss.int.spec.ts
new file mode 100644
index 0000000..e056cd0
--- /dev/null
+++ b/tests/int/rss.int.spec.ts
@@ -0,0 +1,19 @@
+import { describe, expect, it } from 'vitest'
+import { buildRss } from '@/lib/rss'
+
+describe('buildRss', () => {
+  it('produces a valid-looking RSS 2.0 doc', () => {
+    const xml = buildRss({
+      title: 'T',
+      description: 'D',
+      siteUrl: 'https://x.dev',
+      items: [
+        { title: 'A', url: '/a/', description: 'd', publishDate: new Date('2024-01-01') },
+      ],
+    })
+    expect(xml).toContain('<rss version="2.0"')
+    expect(xml).toContain('<title>T</title>')
+    expect(xml).toContain('<link>https://x.dev/a/</link>')
+    expect(xml).toContain('<pubDate>Mon, 01 Jan 2024')
+  })
+})