diff --git a/docs/configuration.rst b/docs/configuration.rst
index 964779f6..487ee25c 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -415,14 +415,10 @@ Description
     The username and password to use when attempting to log in to
     another site.
 
-    Specifying username and password is required for
-
-    * ``nijie``
-    * ``horne``
-
-    and optional for
+    This is supported for
 
     * ``aibooru`` (*)
+    * ``ao3``
     * ``aryion``
     * ``atfbooru`` (*)
     * ``bluesky``
@@ -434,6 +430,7 @@ Description
     * ``e6ai`` (*)
     * ``e926`` (*)
     * ``exhentai``
+    * ``horne`` (R)
     * ``idolcomplex``
     * ``imgbb``
     * ``inkbunny``
@@ -441,8 +438,11 @@ Description
     * ``koharu``
     * ``mangadex``
     * ``mangoxo``
+    * ``newgrounds``
+    * ``nijie`` (R)
     * ``pillowfort``
     * ``sankaku``
+    * ``seiga``
     * ``subscribestar``
     * ``tapas``
     * ``tsumino``
@@ -457,6 +457,9 @@ Description
     (*) The password value for these sites should be
     the API key found in your user profile, not the actual account password.
 
+    (R) Login with username & password or supplying logged-in
+    `cookies <extractor.*.cookies_>`__ is required
+
     Note: Leave the ``password`` value empty or undefined
     to be prompted for a passeword when performing a login
     (see `getpass() <https://docs.python.org/3/library/getpass.html#getpass.getpass>`__).
@@ -467,7 +470,7 @@ extractor.*.input
 Type
     ``bool``
 Default
-    ``true`` if `stdin` is attached to a terminal ,
+    ``true`` if `stdin` is attached to a terminal,
     ``false`` otherwise
 Description
     Allow prompting the user for interactive input.
diff --git a/docs/supportedsites.md b/docs/supportedsites.md
index 4e319879..bfe280bb 100644
--- a/docs/supportedsites.md
+++ b/docs/supportedsites.md
@@ -107,7 +107,7 @@ Consider all listed sites to potentially be NSFW.
     <td>Archive of Our Own</td>
     <td>https://archiveofourown.org/</td>
     <td>Search Results, Series, Tag Searches, User Profiles, Bookmarks, Works</td>
-    <td></td>
+    <td>Supported</td>
 </tr>
 <tr>
     <td>ArtStation</td>
@@ -629,7 +629,7 @@ Consider all listed sites to potentially be NSFW.
     <td>Niconico Seiga</td>
     <td>https://seiga.nicovideo.jp/</td>
     <td>individual Images, User Profiles</td>
-    <td><a href="https://github.com/mikf/gallery-dl#cookies">Cookies</a></td>
+    <td>Supported</td>
 </tr>
 <tr>
     <td>Nozomi.la</td>
diff --git a/gallery_dl/extractor/ao3.py b/gallery_dl/extractor/ao3.py
index 3bb48b50..a0abce05 100644
--- a/gallery_dl/extractor/ao3.py
+++ b/gallery_dl/extractor/ao3.py
@@ -9,7 +9,8 @@
 """Extractors for https://archiveofourown.org/"""
 
 from .common import Extractor, Message
-from .. import text, util
+from .. import text, util, exception
+from ..cache import cache
 
 BASE_PATTERN = (r"(?:https?://)?(?:www\.)?"
                 r"a(?:rchiveofourown|o3)\.(?:org|com|net)")
@@ -20,9 +21,13 @@ class Ao3Extractor(Extractor):
     category = "ao3"
     root = "https://archiveofourown.org"
     categorytransfer = True
+    cookies_domain = ".archiveofourown.org"
+    cookies_names = ("remember_user_token",)
     request_interval = (0.5, 1.5)
 
     def items(self):
+        self.login()
+
         base = self.root + "/works/"
         data = {"_extractor": Ao3WorkExtractor}
 
@@ -32,6 +37,48 @@ class Ao3Extractor(Extractor):
     def works(self):
         return self._pagination(self.groups[0])
 
+    def login(self):
+        if self.cookies_check(self.cookies_names):
+            return
+
+        username, password = self._get_auth_info()
+        if username:
+            return self.cookies_update(self._login_impl(username, password))
+
+    @cache(maxage=90*86400, keyarg=1)
+    def _login_impl(self, username, password):
+        self.log.info("Logging in as %s", username)
+
+        url = self.root + "/users/login"
+        page = self.request(url).text
+
+        pos = page.find('id="loginform"')
+        token = text.extract(
+            page, ' name="authenticity_token" value="', '"', pos)[0]
+        if not token:
+            self.log.error("Unable to extract 'authenticity_token'")
+
+        data = {
+            "authenticity_token": text.unescape(token),
+            "user[login]"       : username,
+            "user[password]"    : password,
+            "user[remember_me]" : "1",
+            "commit"            : "Log In",
+        }
+
+        response = self.request(url, method="POST", data=data)
+        if not response.history:
+            raise exception.AuthenticationError()
+
+        remember = response.history[0].cookies.get("remember_user_token")
+        if not remember:
+            raise exception.AuthenticationError()
+
+        return {
+            "remember_user_token": remember,
+            "user_credentials"   : "1",
+        }
+
     def _pagination(self, path, needle='<li id="work_'):
         while True:
             page = self.request(self.root + path).text
@@ -65,6 +112,8 @@ class Ao3WorkExtractor(Ao3Extractor):
         self.cookies.set("view_adult", "true", domain="archiveofourown.org")
 
     def items(self):
+        self.login()
+
         work_id = self.groups[0]
         url = "{}/works/{}".format(self.root, work_id)
         extr = text.extract_from(self.request(url).text)
@@ -205,6 +254,8 @@ class Ao3UserSeriesExtractor(Ao3Extractor):
     example = "https://archiveofourown.org/users/USER/series"
 
     def items(self):
+        self.login()
+
         base = self.root + "/series/"
         data = {"_extractor": Ao3SeriesExtractor}
 
diff --git a/scripts/supportedsites.py b/scripts/supportedsites.py
index 61bbb05f..764a6f9d 100755
--- a/scripts/supportedsites.py
+++ b/scripts/supportedsites.py
@@ -366,6 +366,7 @@ _APIKEY_WY = ('<a href="https://gdl-org.github.io/docs/configuration.html'
 
 AUTH_MAP = {
     "aibooru"        : "Supported",
+    "ao3"            : "Supported",
     "aryion"         : "Supported",
     "atfbooru"       : "Supported",
     "baraag"         : _OAUTH,
@@ -404,7 +405,7 @@ AUTH_MAP = {
     "ponybooru"      : "API Key",
     "reddit"         : _OAUTH,
     "sankaku"        : "Supported",
-    "seiga"          : _COOKIES,
+    "seiga"          : "Supported",
     "smugmug"        : _OAUTH,
     "subscribestar"  : "Supported",
     "tapas"          : "Supported",