diff --git a/CHANGES.md b/CHANGES.md
index dac4722..9a3e5e6 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -35,6 +35,12 @@
 * Change prevent python-Levenshtein 0.12.1 on non Win due to membug
 
 
+### 0.23.13 (2021-02-26 19:05:00 UTC)
+
+* Add Newznab providers can use API only or API + RSS cache fallback. Tip added to Newznab config/Media Providers/API key
+* Add correct user entry mistakes for nzbs2go api url
+
+
 ### 0.23.12 (2021-02-19 17:00:00 UTC)
 
 * Change allow Python 3.8.8 and 3.9.2
diff --git a/gui/slick/interfaces/default/config_providers.tmpl b/gui/slick/interfaces/default/config_providers.tmpl
index 1d350ea..de7ce35 100644
--- a/gui/slick/interfaces/default/config_providers.tmpl
+++ b/gui/slick/interfaces/default/config_providers.tmpl
@@ -250,7 +250,7 @@
 								<span class="component-title">API key</span>
 								<span class="component-desc">
 									<input type="text" id="${cur_newznab_provider.get_id()}_hash" value="<%= starify(cur_newznab_provider.key) %>" newznab_name="${cur_newznab_provider.get_id()}_hash" class="newznab_key form-control input-sm input350" />
-									<div class="clear-left"><p>get API key from provider website</p></div>
+									<div class="clear-left"><p><code>apikey</code> for API only or <code>i=num&r=key</code> for API + RSS cache fallback</p></div>
 								</span>
 							</label>
 						</div>
@@ -835,7 +835,10 @@ name = '' if not client else get_client_instance(sickbeard.TORRENT_METHOD)().nam
 									<input type="text" id="newznab_key" class="form-control input-sm input350" />
 								</span>
 								<span class="component-desc">
-									<div class="clear-left"><p>note: enter 0 (zero) if not required</p></div>
+									<div class="clear-left">
+										<p><code>apikey</code> for API only or <code>i=num&r=key</code> for API + RSS cache fallback<br>
+										enter 0 (zero) if not required</p>
+									</div>
 								</span>
 							</label>
 						</div>
diff --git a/sickbeard/providers/newznab.py b/sickbeard/providers/newznab.py
index 0bc5377..e7d6cae 100755
--- a/sickbeard/providers/newznab.py
+++ b/sickbeard/providers/newznab.py
@@ -870,13 +870,35 @@ class NewznabProvider(generic.NZBProvider):
                        'attrs': ','.join([k for k, v in iteritems(NewznabConstants.providerToIndexerMapping)
                                           if v in self.caps]),
                        'offset': 0}
-
-        use_rss = self.get_id() in ('ninjacentral', )
-        base_params_rss = {'num': self.limits, 'dl': '1', 'i': '19'}
+        base_params_rss = {'num': self.limits, 'dl': '1'}
+        rss_fallback = False
 
         if isinstance(api_key, string_types) and api_key not in ('0', ''):
             base_params['apikey'] = api_key
             base_params_rss['r'] = api_key
+            args = re.findall(r'.*?([ir])\s*=\s*([^\s&;]*)', api_key)
+            if 1 <= len(args):
+                for (cur_key, cur_value) in args:
+                    base_params_rss[cur_key] = cur_value
+                    if 'r' == cur_key:
+                        rss_fallback = True
+                        base_params['apikey'] = cur_value
+                if not rss_fallback:
+                    logger.warning('Invalid API key config for API to RSS fallback,'
+                                   ' not found: i=num&r=key or i=&r=key or &r=key')
+                    return results, n_spaces
+
+        for mode in search_params:
+            params = dict(needed=needed, max_items=max_items, try_all_searches=try_all_searches,
+                          base_params=base_params, base_params_rss=base_params_rss)
+            results, n_spaces = self._search_core(search_params, **params)
+            if not self.should_skip() and not results and rss_fallback and 'Cache' == mode:
+                results, n_spaces = self._search_core(search_params, use_rss=True, **params)
+            break
+        return results, n_spaces
+
+    def _search_core(self, search_params, needed=None, max_items=400, try_all_searches=False,
+                     use_rss=False, base_params=None, base_params_rss=None):
 
         results, n_spaces = [], {}
         total, cnt, search_url, exit_log = 0, len(results), '', True
diff --git a/sickbeard/webserve.py b/sickbeard/webserve.py
index 9e11d2c..4c75002 100644
--- a/sickbeard/webserve.py
+++ b/sickbeard/webserve.py
@@ -7725,6 +7725,11 @@ class ConfigProviders(Config):
                 if starify(cur_key, True):
                     cur_key = ''
 
+                # correct user entry mistakes
+                test_url = cur_url.lower()
+                if 'nzbs2go' in test_url and test_url.endswith('.com/') or 'api/v1/api' in test_url:
+                    cur_url = 'https://nzbs2go.com/api/v1/'
+
                 new_provider = newznab.NewznabProvider(cur_name, cur_url, key=cur_key)
 
                 cur_id = new_provider.get_id()