diff --git a/docs/youtube.md b/docs/youtube.md
index b169387..cb1671f 100644
--- a/docs/youtube.md
+++ b/docs/youtube.md
@@ -39,6 +39,24 @@ sound**: each app finds the audio stream itself.
   that came through such a server (it downloaded the sound on the server) to the
   channel itself.
 
+## Ad and outro: SponsorBlock
+
+What goes out of the sound — the advertisement and the closing words — is other people's
+work: SponsorBlock (`sponsor.ajay.app`) lets listeners mark a video's parts by category.
+`podcasts/sponsor.py` asks it once per episode (only `sponsor` and `outro`, only parts a
+listener skips, never a part marked `full`) and keeps the answer on the episode
+(`PodcastEpisode.sponsor`); `GET /podcasts/episodes/<id>/sponsor/` answers with it,
+`{"ready": true, "v": 1, "spans": [[from, to], …]}`, empty for an episode that isn't a
+video and with an `error` beside empty spans when SponsorBlock couldn't be asked. Nothing
+else is fetched — no intro, self-promotion, interaction reminder or non-music section.
+
+An answer counts for a week, a failure for an hour (segments are added later; a failure was
+probably the network). A player jumps over those parts and never runs them faster: the
+setting is `skip_sponsor` of this device (on by default, in the play and speed menus), and
+it does something only for YouTube episodes. Nothing of the sound leaves the device for
+this — the video id does, to sponsor.ajay.app, when the server asks (never the sound, and
+never for an episode that isn't a video).
+
 ## Apps
 
 A client that sees a `watch?v=` address resolves it **itself, on the device,
diff --git a/e2e/sponsor.spec.js b/e2e/sponsor.spec.js
new file mode 100644
index 0000000..6eea235
--- /dev/null
+++ b/e2e/sponsor.spec.js
@@ -0,0 +1,178 @@
+// Skipping the ad and the outro of a YouTube episode (docs/youtube.md, podcasts/sponsor.py).
+//
+// The sound of a YouTube episode plays only in an app, so the desktop is imitated here:
+// window.dioraDesktop.youtubeAudio answers with a stream of our own (a silent WAV, served
+// with byte ranges so the player can jump in it). The browser host (podcasts-web.js) is the
+// desktop's podcast host, so this is the code that runs there.
+const { test, expect } = require('@playwright/test');
+const { execFileSync } = require('child_process');
+const path = require('path');
+const { PYTHON, SERVER_ENV, TEST_USER } = require('./env');
+
+const ROOT = path.join(__dirname, '..');
+const VID = 'aqz-KE-bpKQ';
+const WATCH = `https://www.youtube.com/watch?v=${VID}`;
+const SPANS = [[1, 3], [6, 7.5]];   // ad, outro
+const SECONDS = 9;
+const STREAM = '/e2e-silence.wav';
+
+// A silent 8 kHz mono WAV: long enough to reach both parts and past them.
+function wav(seconds, rate = 8000) {
+  const n = seconds * rate;
+  const buf = Buffer.alloc(44 + n * 2);
+  buf.write('RIFF', 0);
+  buf.writeUInt32LE(36 + n * 2, 4);
+  buf.write('WAVE', 8);
+  buf.write('fmt ', 12);
+  buf.writeUInt32LE(16, 16);
+  buf.writeUInt16LE(1, 20);            // PCM
+  buf.writeUInt16LE(1, 22);            // mono
+  buf.writeUInt32LE(rate, 24);
+  buf.writeUInt32LE(rate * 2, 28);     // byte rate
+  buf.writeUInt16LE(2, 32);            // block align
+  buf.writeUInt16LE(16, 34);           // bits
+  buf.write('data', 36);
+  buf.writeUInt32LE(n * 2, 40);
+  return buf;
+}
+
+const BODY = wav(SECONDS);
+
+function seed() {
+  const py = `
+from django.contrib.auth import get_user_model
+from django.utils import timezone
+from podcasts.models import PodcastEpisode, PodcastFeed, PodcastQueue
+import json
+u = get_user_model().objects.get(username=${JSON.stringify(TEST_USER.username)})
+PodcastQueue.objects.filter(user=u).delete()
+PodcastEpisode.objects.filter(feed__user=u).delete()
+PodcastFeed.objects.filter(user=u).delete()
+f = PodcastFeed.objects.create(user=u, rss_url='https://www.youtube.com/feeds/videos.xml?channel_id=UCe2etest',
+                               title='Kanal')
+ep = PodcastEpisode.objects.create(feed=f, guid='yt:video:${VID}', title='Eine Folge',
+                                   audio_url=${JSON.stringify(WATCH)}, pub_date=timezone.now(),
+                                   duration_seconds=${SECONDS},
+                                   sponsor={'v': 1, 'spans': ${JSON.stringify(SPANS)},
+                                            'at': timezone.now().isoformat()})
+PodcastQueue.objects.create(user=u, episode=ep, position=0)
+print('episode', ep.id)
+`;
+  execFileSync(PYTHON, ['manage.py', 'shell', '-c', py], { cwd: ROOT, env: SERVER_ENV, stdio: 'inherit' });
+}
+
+test.beforeAll(seed);
+test.use({ storageState: 'e2e/.auth/user.json' });
+
+// The stream, with byte ranges: without them Chromium may refuse to jump in a file.
+async function serveStream(page) {
+  await page.route(`**${STREAM}`, route => {
+    const range = route.request().headers()['range'];
+    const head = { 'Content-Type': 'audio/wav', 'Accept-Ranges': 'bytes' };
+    if (!range) return route.fulfill({ status: 200, headers: head, body: BODY });
+    const m = /bytes=(\d*)-(\d*)/.exec(range);
+    const from = m && m[1] ? Number(m[1]) : 0;
+    const to = m && m[2] ? Number(m[2]) : BODY.length - 1;
+    return route.fulfill({
+      status: 206,
+      headers: { ...head, 'Content-Range': `bytes ${from}-${to}/${BODY.length}`, 'Content-Length': String(to - from + 1) },
+      body: BODY.subarray(from, to + 1),
+    });
+  });
+}
+
+// The desktop the host talks to, and a look at the player's own position over time.
+async function imitateDesktop(page) {
+  await page.addInitScript(url => {
+    window.dioraDesktop = {
+      youtubeAudio: () => Promise.resolve({ url }),
+      deviceName: 'diora Desktop',
+    };
+    window.__times = [];
+    const Orig = window.Audio;
+    window.Audio = function () {
+      const el = new Orig(...arguments);
+      window.__el = el;
+      el.addEventListener('timeupdate', () => window.__times.push(el.currentTime));
+      el.addEventListener('playing', () => window.__times.push(el.currentTime));
+      return el;
+    };
+    window.Audio.prototype = Orig.prototype;
+  }, STREAM);
+}
+
+// The episode as the host itself holds it (the queue from /podcasts/state/).
+async function episode(page) {
+  return page.evaluate(() => {
+    const s = JSON.parse(window.DioraPodcastHost.podcastState());
+    return (s.queue || []).find(q => /watch\?v=/.test(q.episode__audio_url || '')) || null;
+  });
+}
+
+function inPart(t) {
+  return SPANS.find(([from, to]) => t > from + 0.05 && t < to - 0.05) || null;
+}
+
+test('the ad and the outro are jumped over', async ({ page }) => {
+  const asked = [];
+  page.on('request', r => { if (/\/podcasts\/episodes\/\d+\/sponsor\//.test(r.url())) asked.push(r.url()); });
+  await serveStream(page);
+  await imitateDesktop(page);
+  await page.goto('/');
+  await page.waitForFunction(() => window.DioraPodcastHost, null, { timeout: 15000 });
+  await page.waitForFunction(() => {
+    const s = JSON.parse(window.DioraPodcastHost.podcastState());
+    return (s.queue || []).some(q => /watch\?v=/.test(q.episode__audio_url || ''));
+  }, null, { timeout: 15000 });
+
+  const ep = await episode(page);
+  expect(ep, 'the seeded episode is in the queue').not.toBeNull();
+  await page.evaluate(json => window.DioraPodcastHost.podcastPlayEpisode(json, 0), JSON.stringify(ep));
+
+  // Where the sound is over time, from here (a `timeupdate` comes only every 250 ms).
+  const times = await sample(page, 4.5);
+
+  expect(asked.length, 'the server was asked for the parts').toBeGreaterThan(0);
+  const inside = times.filter(inPart);
+  expect(inside, `no part was played: ${inside.join(', ')} of ${times.length} positions`).toEqual([]);
+  expect(Math.max(...times), 'the sound kept going past the ad').toBeGreaterThan(3.2);
+});
+
+// The player's position, read every 100 ms until it passed `until` (in seconds).
+async function sample(page, until, limit = 250) {
+  const times = [];
+  for (let i = 0; i < limit; i++) {
+    const t = await page.evaluate(() => (window.__el && window.__el.readyState > 0
+      ? window.__el.currentTime : null));
+    if (t !== null) times.push(t);
+    if (t !== null && t > until) break;
+    await page.waitForTimeout(100);
+  }
+  return times;
+}
+
+test('with the setting off nothing is asked and nothing is jumped over', async ({ page }) => {
+  seed();   // the first test left the episode played (and out of the queue)
+  let asked = 0;
+  page.on('request', r => { if (/\/podcasts\/episodes\/\d+\/sponsor\//.test(r.url())) asked++; });
+  await serveStream(page);
+  await imitateDesktop(page);
+  await page.goto('/');
+  // This device's setting, before the host reads it (localStorage, PlaybackPrefs.kt).
+  await page.evaluate(() => localStorage.setItem('dpw_prefs_' + window.USER_ID, JSON.stringify({skip_sponsor: false})));
+  await page.reload();
+  await page.waitForFunction(() => window.DioraPodcastHost, null, { timeout: 15000 });
+  await page.waitForFunction(() => {
+    const s = JSON.parse(window.DioraPodcastHost.podcastState());
+    return (s.queue || []).some(q => /watch\?v=/.test(q.episode__audio_url || ''));
+  }, null, { timeout: 15000 });
+  expect(await page.evaluate(() => JSON.parse(window.DioraPodcastHost.podcastPrefs()).skip_sponsor)).toBe(false);
+
+  const ep = await episode(page);
+  await page.evaluate(json => window.DioraPodcastHost.podcastPlayEpisode(json, 0), JSON.stringify(ep));
+  const times = await sample(page, 4.5);
+
+  expect(asked, 'nothing was asked for').toBe(0);
+  const inside = times.filter(inPart);
+  expect(inside.length, `the ad was played (${inside.join(', ')})`).toBeGreaterThan(0);
+});
diff --git a/podcasts/migrations/0026_podcastepisode_sponsor.py b/podcasts/migrations/0026_podcastepisode_sponsor.py
new file mode 100644
index 0000000..cac71d6
--- /dev/null
+++ b/podcasts/migrations/0026_podcastepisode_sponsor.py
@@ -0,0 +1,18 @@
+# Generated by Django 6.1 on 2026-10-25 15:11
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('podcasts', '0025_podcast_radio'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='podcastepisode',
+            name='sponsor',
+            field=models.JSONField(blank=True, null=True),
+        ),
+    ]
diff --git a/podcasts/models.py b/podcasts/models.py
index 0ecdbda..c24859c 100644
--- a/podcasts/models.py
+++ b/podcasts/models.py
@@ -184,6 +184,9 @@ class PodcastEpisode(models.Model):
     # The pauses for skipping silence in the browser (silence.py), found on
     # first request: {"spans": [[start, end], …]} (+ "error"); null = not yet.
     silences = models.JSONField(null=True, blank=True)
+    # The ad and the outro of a YouTube episode (sponsor.py, SponsorBlock), asked for
+    # on first request: {"spans": [[start, end], …], "at": when, (+ "error")}.
+    sponsor = models.JSONField(null=True, blank=True)
 
     class Meta:
         unique_together = ('feed', 'guid')
diff --git a/podcasts/sponsor.py b/podcasts/sponsor.py
new file mode 100644
index 0000000..8f85bac
--- /dev/null
+++ b/podcasts/sponsor.py
@@ -0,0 +1,144 @@
+"""Skip the ad and the outro of a YouTube episode: what SponsorBlock knows about it.
+
+A YouTube channel is a podcast here (docs/youtube.md): such an episode's audio_url is
+``https://www.youtube.com/watch?v=<11-character id>``, and its sound belongs to the app —
+the server never fetches it. What goes *out* of the sound is other people's work:
+SponsorBlock (sponsor.ajay.app) lets listeners mark a video's parts by category, and the
+two that hurt listening are the advertisement and the closing words. The server asks once
+per episode and keeps the answer on it (PodcastEpisode.sponsor); the player then jumps over
+those parts (podcasts-web.js for the browser and the desktop app, the app's own player for
+Android).
+
+Only those two categories are asked for, and only parts a listener skips: nothing about
+intros, self-promotion, interaction reminders or non-music sections, and no part marked
+``full`` — the whole video sponsored means there would be no sound left.
+"""
+import logging
+from datetime import datetime
+
+import requests
+
+from django.utils import timezone
+
+from . import youtube as youtube_mod
+
+log = logging.getLogger(__name__)
+
+VERSION = 1
+API = 'https://sponsor.ajay.app/api/skipSegments'
+CATEGORIES = ('sponsor', 'outro')
+TIMEOUT = (3, 8)            # connect, read: a player waits for this, so keep it short
+MIN_SPAN = 0.3              # s: a shorter part isn't worth a jump
+STALE = 7 * 24 * 3600       # s: an answer is asked again this long after (segments get added)
+STALE_ERROR = 3600          # s: a failed ask is tried again sooner (it may have been the network)
+
+
+def video_id_of(audio_url):
+    """The video an episode is, judged by its address (the same reading as youtube.py)."""
+    return youtube_mod.video_id_in(audio_url or '')
+
+
+def _spans(segments):
+    """[[from, to], …] in seconds: the parts of `segments` that go, in order, merged.
+
+    What SponsorBlock answered for the categories asked for, as far as it is usable: a
+    segment has a start and an end, `skip` or `mute` means it goes (a jump is quieter than
+    muting and the player jumps anyway), and two parts that touch are one.
+    """
+    found = []
+    for seg in segments or []:
+        if not isinstance(seg, dict):
+            continue
+        if seg.get('category') not in CATEGORIES:
+            continue
+        if seg.get('actionType', 'skip') not in ('skip', 'mute'):
+            continue
+        span = seg.get('segment')
+        if not isinstance(span, (list, tuple)) or len(span) != 2:
+            continue
+        try:
+            start, end = float(span[0]), float(span[1])
+        except (TypeError, ValueError):
+            continue
+        if not (start >= 0 and end > start) or end - start < MIN_SPAN or end != end:  # NaN
+            continue
+        found.append([start, end])
+    found.sort()
+    out = []
+    for start, end in found:
+        if out and start <= out[-1][1] + 0.001:
+            out[-1][1] = max(out[-1][1], end)
+        else:
+            out.append([start, end])
+    return [[round(a, 3), round(b, 3)] for a, b in out]
+
+
+def fetch(video_id):
+    """[[from, to], …] for the video, from SponsorBlock. Raises what the asking raised."""
+    r = requests.get(API, params={'videoID': video_id, 'categories': list(CATEGORIES)},
+                     timeout=TIMEOUT, headers={'User-Agent': 'diora podcast sponsorblock'})
+    if r.status_code == 404:      # nobody has marked this video: not an error
+        return []
+    if r.status_code >= 400:
+        raise RuntimeError(f'HTTP {r.status_code}')
+    try:
+        data = r.json()
+    except ValueError:
+        raise RuntimeError('not JSON')
+    if not isinstance(data, list):
+        raise RuntimeError('unexpected answer')
+    return _spans(data)
+
+
+def ask(video_id):
+    """The result to store on the episode: the parts that go, or why they weren't found."""
+    try:
+        return {'v': VERSION, 'spans': fetch(video_id), 'at': timezone.now().isoformat()}
+    except Exception as e:      # unreachable API, timeout, nonsense: remembered, retried later
+        log.warning('sponsor parts of video %s failed: %s', video_id, e)
+        return {'v': VERSION, 'spans': [], 'error': str(e)[:200] or type(e).__name__,
+                'at': timezone.now().isoformat()}
+
+
+def current(stored):
+    """Whether a stored result still counts (else the episode is asked again).
+
+    A part that goes doesn't change; new ones appear, though, so an episode is asked again
+    after a week — and a failure after an hour, since it was probably the network.
+    """
+    if not stored or stored.get('v') != VERSION or 'spans' not in stored:
+        return False
+    age = STALE_ERROR if stored.get('error') else STALE
+    at = stored.get('at')
+    if not at:
+        return False
+    try:
+        when = datetime.fromisoformat(at)
+    except (TypeError, ValueError):
+        return False
+    if timezone.is_naive(when):
+        when = timezone.make_aware(when)
+    return (timezone.now() - when).total_seconds() < age
+
+
+def spans_of(episode):
+    """[[from, to], …]: what to leave out of this episode, asking SponsorBlock if need be.
+
+    Nothing at all for an episode that isn't a video (SponsorBlock knows only YouTube), and
+    nothing when the asking fails. The episode is only handed back changed through the DB
+    (`update`), so a caller that keeps the row doesn't have to save it.
+    """
+    from .models import PodcastEpisode
+    empty = {'ready': True, 'v': VERSION, 'spans': []}
+    video_id = video_id_of(episode.audio_url)
+    if not video_id:
+        return empty
+    stored = episode.sponsor
+    if not current(stored):
+        stored = ask(video_id)
+        PodcastEpisode.objects.filter(pk=episode.pk).update(sponsor=stored)
+        episode.sponsor = stored
+    out = dict(empty, spans=stored.get('spans', []))
+    if stored.get('error'):
+        out['error'] = stored['error']
+    return out
diff --git a/podcasts/test_sponsor.py b/podcasts/test_sponsor.py
new file mode 100644
index 0000000..69cb992
--- /dev/null
+++ b/podcasts/test_sponsor.py
@@ -0,0 +1,196 @@
+"""Skipping the ad and the outro of a YouTube episode (sponsor.py)."""
+from datetime import timedelta
+from unittest.mock import patch
+
+from django.contrib.auth.models import User
+from django.test import TestCase
+from django.utils import timezone
+
+from . import sponsor
+from .models import PodcastEpisode, PodcastFeed
+
+VIDEO = 'https://www.youtube.com/watch?v=aqz-KE-bpKQ'
+VID = 'aqz-KE-bpKQ'
+
+
+def seg(start, end, category='sponsor', action='skip'):
+    return {'UUID': f'{category}-{start}', 'category': category, 'actionType': action,
+            'segment': [start, end], 'votes': 10, 'videoDuration': 600}
+
+
+class SpanTests(TestCase):
+    """What is taken out of SponsorBlock's answer."""
+
+    def test_only_sponsor_and_outro(self):
+        self.assertEqual(sponsor._spans([
+            seg(10, 20), seg(30, 40, 'outro'),
+            seg(50, 60, 'intro'), seg(70, 80, 'selfpromo'),
+            seg(90, 100, 'interaction'), seg(110, 120, 'music_offtopic'),
+        ]), [[10, 20], [30, 40]])
+
+    def test_full_and_poi_segments_are_left_alone(self):
+        # "full": the whole video is a sponsor — jumping would leave no sound at all.
+        self.assertEqual(sponsor._spans([seg(0, 600, 'sponsor', 'full')]), [])
+
+    def test_mute_counts_as_skipped(self):
+        self.assertEqual(sponsor._spans([seg(10, 20, 'sponsor', 'mute')]), [[10, 20]])
+
+    def test_touching_parts_become_one(self):
+        self.assertEqual(sponsor._spans([seg(10, 20), seg(20, 30)]), [[10, 30]])
+        self.assertEqual(sponsor._spans([seg(10, 20), seg(19.5, 30)]), [[10, 30]])
+
+    def test_order_does_not_matter(self):
+        self.assertEqual(sponsor._spans([seg(30, 40, 'outro'), seg(10, 20)]), [[10, 20], [30, 40]])
+
+    def test_nonsense_is_ignored(self):
+        self.assertEqual(sponsor._spans([
+            seg(10, 20), 'nonsense', {}, {'category': 'sponsor'}, {'category': 'sponsor', 'segment': [1]},
+            {'category': 'sponsor', 'segment': ['a', 'b']}, {'category': 'sponsor', 'segment': [20, 10]},
+            {'category': 'sponsor', 'segment': [-5, 5]}, seg(30, 30.1),      # too short to be worth it
+        ]), [[10, 20]])
+
+    def test_nothing_at_all(self):
+        self.assertEqual(sponsor._spans(None), [])
+        self.assertEqual(sponsor._spans([]), [])
+
+    def test_the_video_id_of_an_episode(self):
+        self.assertEqual(sponsor.video_id_of(VIDEO), VID)
+        self.assertEqual(sponsor.video_id_of(f'https://example.org/podcasts/{VID}.mp3'), VID)
+        self.assertEqual(sponsor.video_id_of('https://example.org/folge.mp3'), '')
+
+
+class FetchTests(TestCase):
+    def setUp(self):
+        self.answers = []
+
+        def get(url, **kw):
+            self.asked = (url, kw.get('params'), kw.get('timeout'))
+            return self.answers.pop(0)
+
+        self.get = get
+
+    def _answer(self, status=200, body=None):
+        class R:
+            status_code = status
+
+            def json(_self):
+                return body
+        r = R()
+        r.status_code = status
+        return r
+
+    def test_a_video_nobody_marked_is_not_an_error(self):
+        self.answers = [self._answer(404)]
+        with patch('podcasts.sponsor.requests.get', self.get):
+            self.assertEqual(sponsor.fetch(VID), [])
+        url, params, timeout = self.asked
+        self.assertEqual(url, sponsor.API)
+        self.assertEqual(params['videoID'], VID)
+        self.assertEqual(params['categories'], ['sponsor', 'outro'])
+        self.assertEqual(timeout, sponsor.TIMEOUT)
+
+    def test_what_the_api_answers_is_read(self):
+        self.answers = [self._answer(200, [seg(60, 90, 'outro'), seg(10, 20)])]
+        with patch('podcasts.sponsor.requests.get', self.get):
+            self.assertEqual(sponsor.fetch(VID), [[10, 20], [60, 90]])
+
+    def test_a_broken_answer_is_an_error(self):
+        for answer in (self._answer(500), self._answer(200, {'error': 'nope'})):
+            self.answers = [answer]
+            with patch('podcasts.sponsor.requests.get', self.get):
+                with self.assertRaises(RuntimeError):
+                    sponsor.fetch(VID)
+
+    def test_ask_remembers_an_error_instead_of_raising(self):
+        def boom(url, **kw):
+            raise OSError('no route to host')
+        with patch('podcasts.sponsor.requests.get', boom):
+            got = sponsor.ask(VID)
+        self.assertEqual(got['spans'], [])
+        self.assertEqual(got['v'], sponsor.VERSION)
+        self.assertIn('no route', got['error'])
+        self.assertTrue(got['at'])
+
+    def test_a_stored_answer_is_used_until_it_is_old(self):
+        now = timezone.now().isoformat()
+        fresh = {'v': sponsor.VERSION, 'spans': [[1, 2]], 'at': now}
+        self.assertTrue(sponsor.current(fresh))
+        self.assertFalse(sponsor.current(None))
+        self.assertFalse(sponsor.current({}))
+        self.assertFalse(sponsor.current({'v': sponsor.VERSION - 1, 'spans': [], 'at': now}))
+        self.assertFalse(sponsor.current({'v': sponsor.VERSION, 'spans': []}))   # no "at"
+
+    def test_a_failure_is_asked_again_sooner_than_an_answer(self):
+        def ago(seconds):
+            return (timezone.now() - timedelta(seconds=seconds)).isoformat()
+        old = {'v': sponsor.VERSION, 'spans': [[1, 2]], 'at': ago(sponsor.STALE + 60)}
+        self.assertFalse(sponsor.current(old))
+        self.assertTrue(sponsor.current(dict(old, at=ago(sponsor.STALE - 60))))
+        failed = {'v': sponsor.VERSION, 'spans': [], 'error': 'HTTP 500', 'at': ago(sponsor.STALE_ERROR + 60)}
+        self.assertFalse(sponsor.current(failed))
+
+
+class EpisodeSponsorViewTests(TestCase):
+    def setUp(self):
+        self.user = User.objects.create_user(username='alice', password='pw12345678')
+        self.client.force_login(self.user)
+        self.feed = PodcastFeed.objects.create(user=self.user, rss_url='https://www.youtube.com/feeds/videos.xml?channel_id=UCx',
+                                              title='Kanal')
+        self.video = PodcastEpisode.objects.create(
+            feed=self.feed, guid=f'yt:video:{VID}', title='Eine Folge', audio_url=VIDEO,
+            pub_date=timezone.now())
+        self.other = PodcastEpisode.objects.create(
+            feed=self.feed, guid='e1', title='Eine Folge', audio_url='https://example.org/e1.mp3',
+            pub_date=timezone.now())
+        self.answers = []
+
+    def _get(self, url, **kw):
+        return self.answers.pop(0)
+
+    def _answer(self, body):
+        class R:
+            status_code = 200
+
+            def json(_self):
+                return body
+        return R()
+
+    def url(self, ep):
+        return f'/podcasts/episodes/{ep.id}/sponsor/'
+
+    def test_a_video_is_asked_once_and_the_answer_is_kept(self):
+        self.answers = [self._answer([seg(10, 20), seg(60, 90, 'outro')])]
+        with patch('podcasts.sponsor.requests.get', self._get):
+            d = self.client.get(self.url(self.video)).json()
+        self.assertEqual(d, {'ready': True, 'v': sponsor.VERSION, 'spans': [[10, 20], [60, 90]]})
+        self.assertEqual(PodcastEpisode.objects.get(pk=self.video.pk).sponsor['spans'], [[10, 20], [60, 90]])
+        # Kept: the second call doesn't ask again.
+        with patch('podcasts.sponsor.requests.get', self._get):
+            d = self.client.get(self.url(self.video)).json()
+        self.assertEqual(d['spans'], [[10, 20], [60, 90]])
+
+    def test_a_failed_ask_answers_empty_and_is_remembered(self):
+        def boom(url, **kw):
+            raise OSError('timed out')
+        with patch('podcasts.sponsor.requests.get', boom):
+            d = self.client.get(self.url(self.video)).json()
+        self.assertEqual(d['spans'], [])
+        self.assertEqual(d['error'], 'timed out')
+        self.assertIn('error', PodcastEpisode.objects.get(pk=self.video.pk).sponsor)
+
+    def test_an_episode_that_is_no_video_is_never_asked_for(self):
+        with patch('podcasts.sponsor.requests.get', self._get):
+            d = self.client.get(self.url(self.other)).json()
+        self.assertEqual(d, {'ready': True, 'v': sponsor.VERSION, 'spans': []})
+        self.assertIsNone(PodcastEpisode.objects.get(pk=self.other.pk).sponsor)
+
+    def test_a_foreign_episode_is_not_found(self):
+        other = User.objects.create_user(username='bob', password='pw12345678')
+        feed = PodcastFeed.objects.create(user=other, rss_url='https://example.org/f', title='F')
+        ep = PodcastEpisode.objects.create(feed=feed, guid='x', title='X', audio_url=VIDEO,
+                                          pub_date=timezone.now())
+        self.assertEqual(self.client.get(self.url(ep)).status_code, 404)
+
+    def test_asking_without_a_login_is_refused(self):
+        self.client.logout()
+        self.assertEqual(self.client.get(self.url(self.video)).status_code, 401)
diff --git a/podcasts/urls.py b/podcasts/urls.py
index 933f93e..aaaaa25 100644
--- a/podcasts/urls.py
+++ b/podcasts/urls.py
@@ -29,6 +29,7 @@ urlpatterns = [
     path('episodes/<int:pk>/', views.episode_detail, name='podcast_episode_detail'),
     path('episodes/<int:pk>/transcript/', views.episode_transcript, name='podcast_episode_transcript'),
     path('episodes/<int:pk>/silences/', views.episode_silences, name='podcast_episode_silences'),
+    path('episodes/<int:pk>/sponsor/', views.episode_sponsor, name='podcast_episode_sponsor'),
     path('episodes/<int:pk>/favorite/', views.set_favorite, name='podcast_set_favorite'),
     path('stats/', views.podcast_stats, name='podcast_stats'),
     path('queue/', views.queue_get, name='podcast_queue_get'),
diff --git a/podcasts/views.py b/podcasts/views.py
index 29e9d70..b856077 100644
--- a/podcasts/views.py
+++ b/podcasts/views.py
@@ -27,6 +27,7 @@ from django.views.decorators.http import require_http_methods
 
 from . import chapters as chapters_mod
 from . import silence as silence_mod
+from . import sponsor as sponsor_mod
 from . import feedext
 from . import transcripts as transcripts_mod
 from . import youtube as youtube_mod
@@ -1481,6 +1482,22 @@ def episode_silences(request, pk):
                          **({'error': ep.silences['error']} if ep.silences.get('error') else {})})
 
 
+@csrf_exempt
+@require_http_methods(['GET'])
+def episode_sponsor(request, pk):
+    """What to leave out of the episode's sound: the ad and the outro, from SponsorBlock
+    (sponsor.py). {"ready": true, "v": 1, "spans": [[from, to], …]} — asked for on the
+    first request and then kept on the episode; empty for an episode that isn't a video,
+    and an "error" beside empty spans when SponsorBlock couldn't be asked."""
+    if not request.user.is_authenticated:
+        return JsonResponse({'error': 'authentication required'}, status=401)
+    ep = PodcastEpisode.objects.filter(pk=pk, feed__user=request.user).only(
+        'id', 'sponsor', 'audio_url').first()
+    if ep is None:
+        return JsonResponse({'error': 'not found'}, status=404)
+    return JsonResponse(sponsor_mod.spans_of(ep))
+
+
 @csrf_exempt
 @require_http_methods(['GET'])
 def episode_transcript(request, pk):
diff --git a/static/js/podcasts-web.js b/static/js/podcasts-web.js
index 35438c2..2b0b7ea 100644
--- a/static/js/podcasts-web.js
+++ b/static/js/podcasts-web.js
@@ -482,7 +482,9 @@
     smart_played: [0, 15, 30, 45, 60, 120, 300, 600],
   };
   const prefs = Object.assign({speed: 1, skip_back: 15, skip_forward: 30, remove_played: true, smart_played: 30,
-    sleep_last: 15, sleep_auto: false, sleep_from: 22, sleep_to: 6, skip_silence: false}, load('prefs', {}));
+    sleep_last: 15, sleep_auto: false, sleep_from: 22, sleep_to: 6, skip_silence: false,
+    // Ad and outro of a YouTube episode (sponsor.py): on, since that is what it is for.
+    skip_sponsor: true}, load('prefs', {}));
 
   // Skip lengths and "counts as played": the account's where it has them, else this browser's.
   function eff(name) {
@@ -504,6 +506,8 @@
       prefs.remove_played = !!value;
     } else if (name === 'skip_silence') {
       prefs.skip_silence = !!value;   // the server finds the pauses, we jump over them (below)
+    } else if (name === 'skip_sponsor') {
+      prefs.skip_sponsor = !!value;   // SponsorBlock knows the ad and the outro (below)
     } else if (name === 'sleep_from' || name === 'sleep_to') {
       if (!(Number.isInteger(value) && value >= 0 && value <= 23)) return;
       prefs[name] = value;
@@ -517,7 +521,7 @@
   function prefsJson() {
     return {speed: prefs.speed, skip_back: eff('skip_back'), skip_forward: eff('skip_forward'),
       remove_played: prefs.remove_played, smart_played: eff('smart_played'), feeds: {},
-      skip_silence: !!prefs.skip_silence,
+      skip_silence: !!prefs.skip_silence, skip_sponsor: !!prefs.skip_sponsor,
       sleep_from: sleepHour('sleep_from', 22), sleep_to: sleepHour('sleep_to', 6)};
   }
 
@@ -1338,6 +1342,70 @@
   document.addEventListener('visibilitychange', silenceWatch);
   audio.addEventListener('timeupdate', () => { if (!silenceTimer && !audio.paused) silenceWatch(); });
 
+  // ---- skip the ad and the outro (SponsorBlock) -----------------------------------------
+  // A YouTube episode's sound is the video's, and its ad and closing words are marked by
+  // other listeners (sponsor.py on the server, docs/youtube.md). Only YouTube episodes:
+  // SponsorBlock knows nothing else. They are simply jumped over — such a part is long,
+  // and a jump is quieter than running it through faster or muting it.
+  const SPONSOR_LEAD = 0.15;    // s: jump this early, a timer is a little late
+  let sponsorTimer = null;
+  let sponsorDone = -1;         // the end of the part last jumped over (not entered again)
+
+  const sponsor = {id: null, spans: null, asked: 0};
+
+  // [[from, to], …] in seconds: what to leave out of this episode, once the server said.
+  function sponsorSpans() {
+    const id = curId();
+    if (id == null || !prefs.skip_sponsor || !cur || !YOUTUBE.test(cur.episode__audio_url || '')) return null;
+    if (sponsor.id !== id) { sponsor.id = id; sponsor.spans = null; sponsor.asked = 0; sponsorDone = -1; }
+    if (!sponsor.spans && Date.now() - sponsor.asked > 20000) {
+      sponsor.asked = Date.now();
+      fetch(`/podcasts/episodes/${id}/sponsor/`, {credentials: 'same-origin', cache: 'no-store'})
+        .then(r => (r.ok ? r.json() : null))
+        .then(d => { if (d && d.v === 1 && sponsor.id === id) sponsor.spans = d.spans || []; })
+        .catch(() => {});
+    }
+    return sponsor.spans;
+  }
+
+  function sponsorSchedule(ms) {
+    clearTimeout(sponsorTimer);
+    sponsorTimer = setTimeout(sponsorTick, Math.max(20, Math.min(ms, 2000)));
+  }
+
+  function sponsorTick() {
+    sponsorTimer = null;
+    if (!loaded || audio.paused || audio.seeking) return;
+    const spans = sponsorSpans();
+    if (!spans) { if (spans === null) sponsorSchedule(1000); return; }   // still asking the server
+    const t = audio.currentTime;
+    for (const [from, to] of spans) {   // in order
+      if (to <= t || to === sponsorDone) continue;
+      if (from <= t) {                  // inside a part that goes
+        sponsorDone = to;
+        try { audio.currentTime = to; } catch (e) {}
+        sponsorSchedule(100);
+        return;
+      }
+      sponsorSchedule((from - t - SPONSOR_LEAD) / (audio.playbackRate || 1) * 1000 + 30);
+      return;
+    }
+  }
+
+  function sponsorWatch() {
+    clearTimeout(sponsorTimer);
+    sponsorTimer = null;
+    if (loaded && !audio.paused) sponsorTick();
+  }
+  audio.addEventListener('playing', sponsorWatch);
+  audio.addEventListener('pause', sponsorWatch);
+  audio.addEventListener('ended', sponsorWatch);
+  audio.addEventListener('emptied', sponsorWatch);
+  audio.addEventListener('seeked', () => { sponsorDone = -1; sponsorWatch(); });
+  audio.addEventListener('ratechange', () => { if (sponsorTimer) sponsorWatch(); });  // the jump is timed by rate
+  document.addEventListener('visibilitychange', sponsorWatch);
+  audio.addEventListener('timeupdate', () => { if (!sponsorTimer && !audio.paused) sponsorWatch(); });
+
   // ---- radio and podcasts take turns ---------------------------------------------------
 
   function stopRadio() {
diff --git a/static/js/sw.js b/static/js/sw.js
index a125705..14e6fac 100644
--- a/static/js/sw.js
+++ b/static/js/sw.js
@@ -2,7 +2,7 @@
  * diora service worker — caches the app shell for offline use.
  */
 
-const CACHE = 'diora-v154';
+const CACHE = 'diora-v155';
 const SHELL = [
   '/static/css/app.css',
   '/static/js/app/01-core.js',
diff --git a/static/podcasts/native-podcast.js b/static/podcasts/native-podcast.js
index 71aa62d..d0b4ddb 100644
--- a/static/podcasts/native-podcast.js
+++ b/static/podcasts/native-podcast.js
@@ -1,4 +1,4 @@
-// Copied from diora-android 7f37d4e 2026-10-25: web-native/static/native-podcast.js
+// Copied from diora-android e287f48 2026-10-25: web-native/static/native-podcast.js
 // by tools/sync_podcast_ui.py. Do not edit here: change it in diora-android
 // and copy again. The browser host is static/js/podcasts-web.js.
 
@@ -666,7 +666,8 @@
         keepSkippedItem(),
         deleteDequeueItem(),
       ]),
-      group('▶', 'Abspielen', ['Sprungweiten', 'speed_presets' in s && 'Tempo', 'skip_silence' in prefs && 'Stille', '„gehört“',
+      group('▶', 'Abspielen', ['Sprungweiten', 'speed_presets' in s && 'Tempo', 'skip_silence' in prefs && 'Stille',
+        'skip_sponsor' in prefs && 'Werbung', '„gehört“',
         'times_by_speed' in s && 'Zeiten', 'headset_next' in prefs && 'Kopfhörer',
         'notify_buttons' in prefs && 'Benachrichtigung'].filter(Boolean).join(', '), () => [
         skipItem('skip_back', 'Zurückspringen', SKIPS),
@@ -674,6 +675,7 @@
         'speed_presets' in s && {icon: '»', label: 'Tempo-Voreinstellungen', hint: presets().map(speedLabel).join(' · '),
           action: () => presetsEditor()},
         silenceItem(),
+        sponsorItem(),
         playedItem(),
         timesItem(),
         headsetItem(),
@@ -931,6 +933,28 @@
             action: () => N.podcastSetPref('skip_silence', !on)};
   }
 
+  // „Werbung und Schluss überspringen“ next to „Stille überspringen“ in the speed menu: one
+  // setting for this device, no per-podcast choice (only YouTube episodes have it at all).
+  function sponsorSpeedItems() {
+    const prefs = devicePrefs();
+    if (!N.podcastSetPref || !('skip_sponsor' in prefs)) return [];
+    const device = !!prefs.skip_sponsor;
+    return [{icon: device ? '☑' : '☐', label: 'Werbung und Schluss überspringen',
+      hint: (device ? 'an' : 'aus') + ' · YouTube-Folgen (SponsorBlock)',
+      action: () => { N.podcastSetPref('skip_sponsor', !device);
+        toast(device ? 'Werbung und Schluss werden gespielt' : 'Werbung und Schluss werden übersprungen'); }}];
+  }
+
+  // Ad and outro of a YouTube episode (server: sponsor.py, SponsorBlock). Only where the
+  // player does it at all — the app knows the setting once PlaybackPrefs has it.
+  function sponsorItem() {
+    if (!N.podcastSetPref || !('skip_sponsor' in devicePrefs())) return null;
+    const on = !!devicePrefs().skip_sponsor;
+    return {icon: on ? '☑' : '☐', label: 'Werbung und Schluss überspringen',
+            hint: on ? 'an: in YouTube-Folgen' : 'aus',
+            action: () => N.podcastSetPref('skip_sponsor', !on)};
+  }
+
   function devicePrefs() {
     return parse(N.podcastPrefs ? N.podcastPrefs() : '{}', {});
   }
@@ -4948,13 +4972,13 @@ neuesten Folgen) und die vorhandenen Ordner. Schlage nur Änderungen vor, die wi
         label: speedLabel(s),
         action: () => (forPodcast ? N.podcastSpeedForPodcast(s) : N.podcastSpeed(s)),
       })).concat(forPodcast && own ? [{icon: '↺', label: 'Wie alle anderen Podcasts', action: () => N.podcastSpeedForPodcast(0)}] : [])
-        .concat(presetsEditItem(), silenceSpeedItems()));
+        .concat(presetsEditItem(), silenceSpeedItems(), sponsorSpeedItems()));
     if (!N.podcastSpeedForPodcast || !player.feedId) { pick(false); return; }
     openSheet('Geschwindigkeit', [
       {icon: '◎', label: 'Für alle Podcasts', hint: own ? null : speedLabel(player.speed || 1), action: () => pick(false)},
       {icon: '◉', label: `Nur für „${plain(player.feed)}“`, hint: own ? speedLabel(player.speed || 1) : 'noch keine eigene',
        action: () => pick(true)},
-    ].concat(presetsEditItem(), silenceSpeedItems()));
+    ].concat(presetsEditItem(), silenceSpeedItems(), sponsorSpeedItems()));
   }
 
   // „Stille überspringen“ where AntennaPod has it: in the speed menu. For all podcasts (this