diff --git a/add_links/api.py b/add_links/api.py
index d84f4d6..e0174b7 100644
--- a/add_links/api.py
+++ b/add_links/api.py
@@ -1,5 +1,5 @@
 import re
-from typing import Any
+import typing
 
 import requests
 from requests.adapters import HTTPAdapter
@@ -8,6 +8,8 @@ from simplejson.scanner import JSONDecodeError
 from .language import get_current_language
 from .util import is_disambig
 
+StrDict = dict[str, typing.Any]
+
 ua = (
     "find-link/2.2 "
     + "(https://github.com/EdwardBetts/find_link; contact: edward@4angle.com)"
@@ -20,42 +22,47 @@ def get_query_url() -> str:
     return f"https://{get_current_language()}.wikipedia.org/w/api.php"
 
 
-sessions = {}
+sessions: dict[str, requests.sessions.Session] = {}
 
 
-def get_session():
+def get_session() -> requests.sessions.Session:
+    """Get requests session."""
     lang = get_current_language()
     if lang in sessions:
         return sessions[lang]
     s = requests.Session()
     s.headers = {"User-Agent": ua}
     s.mount("https://en.wikipedia.org", HTTPAdapter(max_retries=10))
-    s.params = {
-        "format": "json",
-        "action": "query",
-        "formatversion": 2,
-    }
+    s.params = typing.cast(
+        dict[str, str | int],
+        {
+            "format": "json",
+            "action": "query",
+            "formatversion": 2,
+        },
+    )
     sessions[lang] = s
     return s
 
 
 class MediawikiError(Exception):
-    pass
+    """Mediawiki error."""
 
 
 class MultipleRedirects(Exception):
-    pass
+    """Multiple redirects."""
 
 
 class IncompleteReply(Exception):
-    pass
+    """Incomplete reply."""
 
 
 class MissingPage(Exception):
-    pass
+    """Missing page."""
 
 
-def check_for_error(json_data):
+def check_for_error(json_data: dict[str, typing.Any]) -> None:
+    """Check MediaWiki API reply for error."""
     if "error" in json_data:
         raise MediawikiError(json_data["error"]["info"])
 
@@ -65,13 +72,13 @@ webpage_error = (
 )
 
 
-def api_get(params: dict[str, Any]) -> dict[str, Any]:
+def api_get(params: StrDict) -> StrDict:
     """Make call to Wikipedia API."""
     s = get_session()
 
     r = s.get(get_query_url(), params=params)
     try:
-        ret = r.json()
+        ret: StrDict = r.json()
     except JSONDecodeError:
         if webpage_error in r.text:
             raise MediawikiError(webpage_error)
@@ -81,22 +88,23 @@ def api_get(params: dict[str, Any]) -> dict[str, Any]:
     return ret
 
 
-def get_first_page(params: dict[str, str]) -> dict[str, Any]:
+def get_first_page(params: dict[str, str]) -> StrDict:
     """Run Wikipedia API query and return the first page."""
-    page = api_get(params)["query"]["pages"][0]
+    page: StrDict = api_get(params)["query"]["pages"][0]
     if page.get("missing"):
         raise MissingPage
     return page
 
 
-def random_article_list(limit=50):
+def random_article_list(limit: int = 50) -> list[StrDict]:
+    """Get random sample of articles."""
     params = {
         "list": "random",
         "rnnamespace": "0",
         "rnlimit": limit,
     }
 
-    return api_get(params)["query"]["random"]
+    return typing.cast(list[StrDict], api_get(params)["query"]["random"])
 
 
 def wiki_search(q):
@@ -185,23 +193,6 @@ def categorymembers(q: str) -> list[str]:
     return [i["title"] for i in ret["categorymembers"] if i["title"] != q]
 
 
-def page_links(titles):  # unused
-    titles = list(titles)
-    assert titles
-    params = {
-        "prop": "links",
-        "pllimit": 500,
-        "plnamespace": 0,
-        "titles": "|".join(titles),
-    }
-    ret = api_get(params)["query"]
-    return dict(
-        (doc["title"], {l["title"] for l in doc["links"]})
-        for doc in ret["pages"].values()
-        if "links" in doc
-    )
-
-
 def find_disambig(titles: list[str]) -> list[str]:
     """Find disambiguation articles in the given list of titles."""
     titles = list(titles)
@@ -235,7 +226,8 @@ def find_disambig(titles: list[str]) -> list[str]:
     return disambig
 
 
-def wiki_redirects(q):  # pages that link here
+def wiki_redirects(q: str) -> typing.Iterator[str]:
+    """Pages that link here."""
     params = {
         "list": "backlinks",
         "blfilterredir": "redirects",
@@ -269,7 +261,8 @@ def wiki_backlink(q: str) -> tuple[set[str], set[str]]:
     return (articles, redirects)
 
 
-def call_get_diff(title, section_num, section_text):
+def call_get_diff(title: str, section_num: int, section_text: str) -> str:
+    """Get diff from Wikipedia."""
     data = {
         "prop": "revisions",
         "rvprop": "timestamp",
@@ -281,4 +274,4 @@ def call_get_diff(title, section_num, section_text):
     s = get_session()
     ret = s.post(get_query_url(), data=data).json()
     check_for_error(ret)
-    return ret["query"]["pages"][0]["revisions"][0]["diff"]["body"]
+    return typing.cast(str, ret["query"]["pages"][0]["revisions"][0]["diff"]["body"])