diff --git a/Makefile b/Makefile
index 10c88fb0..311b6bc4 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,7 @@ TEST = tests
 test:
 	pytest -v $(TEST)  --cov-report term --cov-report xml --cov=$(APP)
 lint:
-	pylint $(APP) || true
+	pylint $(APP)
 
 fmt:
 	invoke fmt
diff --git a/app/__init__.py b/app/__init__.py
index 76345caa..c43ae7ac 100644
--- a/app/__init__.py
+++ b/app/__init__.py
@@ -1,2 +1,7 @@
+"""
+Corona Virus Tracker API
+~~~~~~~~~~~~~~~~~~~~~~~~
+API for tracking the global coronavirus (COVID-19, SARS-CoV-2) outbreak.
+"""
 # See PEP396.
-__version__ = "2.0"
+__version__ = "2.0.1"
diff --git a/app/config/settings.py b/app/config/settings.py
index 27c907bd..4a02a734 100644
--- a/app/config/settings.py
+++ b/app/config/settings.py
@@ -1,3 +1,4 @@
+"""app.config.settings.py"""
 import os
 
 # Load enviroment variables from .env file.
@@ -5,7 +6,5 @@
 
 load_dotenv()
 
-"""
-The port to serve the app application on.
-"""
-PORT = int(os.getenv("PORT", 5000))
+# The port to serve the app application on.
+PORT = int(os.getenv("PORT", "5000"))
diff --git a/app/coordinates.py b/app/coordinates.py
index cc27a8e3..be972c6e 100644
--- a/app/coordinates.py
+++ b/app/coordinates.py
@@ -1,3 +1,6 @@
+"""app.coordinates.py"""
+
+
 class Coordinates:
     """
     A position on earth using decimal coordinates (latitude and longitude).
diff --git a/app/data/__init__.py b/app/data/__init__.py
index 73468add..aef58e8c 100644
--- a/app/data/__init__.py
+++ b/app/data/__init__.py
@@ -1,8 +1,9 @@
+"""app.data"""
 from ..services.location.csbs import CSBSLocationService
 from ..services.location.jhu import JhuLocationService
 
 # Mapping of services to data-sources.
-data_sources = {"jhu": JhuLocationService(), "csbs": CSBSLocationService()}
+DATA_SOURCES = {"jhu": JhuLocationService(), "csbs": CSBSLocationService()}
 
 
 def data_source(source):
@@ -12,4 +13,4 @@ def data_source(source):
     :returns: The service.
     :rtype: LocationService
     """
-    return data_sources.get(source.lower())
+    return DATA_SOURCES.get(source.lower())
diff --git a/app/location/__init__.py b/app/location/__init__.py
index 4782fddb..d12f28c3 100644
--- a/app/location/__init__.py
+++ b/app/location/__init__.py
@@ -1,14 +1,18 @@
+"""app.location"""
 from ..coordinates import Coordinates
 from ..utils import countries
 from ..utils.populations import country_population
 
 
-class Location:
+# pylint: disable=redefined-builtin,invalid-name
+class Location:  # pylint: disable=too-many-instance-attributes
     """
     A location in the world affected by the coronavirus.
     """
 
-    def __init__(self, id, country, province, coordinates, last_updated, confirmed, deaths, recovered):
+    def __init__(
+        self, id, country, province, coordinates, last_updated, confirmed, deaths, recovered
+    ):  # pylint: disable=too-many-arguments
         # General info.
         self.id = id
         self.country = country.strip()
@@ -31,7 +35,7 @@ def country_code(self):
         :returns: The country code.
         :rtype: str
         """
-        return (countries.country_code(self.country) or countries.default_country_code).upper()
+        return (countries.country_code(self.country) or countries.DEFAULT_COUNTRY_CODE).upper()
 
     @property
     def country_population(self):
@@ -71,6 +75,7 @@ class TimelinedLocation(Location):
     A location with timelines.
     """
 
+    # pylint: disable=too-many-arguments
     def __init__(self, id, country, province, coordinates, last_updated, timelines):
         super().__init__(
             # General info.
@@ -88,6 +93,7 @@ def __init__(self, id, country, province, coordinates, last_updated, timelines):
         # Set timelines.
         self.timelines = timelines
 
+    # pylint: disable=arguments-differ
     def serialize(self, timelines=False):
         """
         Serializes the location into a dict.
diff --git a/app/location/csbs.py b/app/location/csbs.py
index 0b7c27f8..649e8b22 100644
--- a/app/location/csbs.py
+++ b/app/location/csbs.py
@@ -1,3 +1,4 @@
+"""app.locations.csbs.py"""
 from . import Location
 
 
@@ -6,6 +7,7 @@ class CSBSLocation(Location):
     A CSBS (county) location.
     """
 
+    # pylint: disable=too-many-arguments,redefined-builtin
     def __init__(self, id, state, county, coordinates, last_updated, confirmed, deaths):
         super().__init__(
             # General info.
@@ -23,7 +25,7 @@ def __init__(self, id, state, county, coordinates, last_updated, confirmed, deat
         self.state = state
         self.county = county
 
-    def serialize(self, timelines=False):
+    def serialize(self, timelines=False):  # pylint: disable=arguments-differ,unused-argument
         """
         Serializes the location into a dict.
 
diff --git a/app/main.py b/app/main.py
index b34d6629..75805ebc 100644
--- a/app/main.py
+++ b/app/main.py
@@ -11,8 +11,8 @@
 from fastapi.responses import JSONResponse
 
 from .data import data_source
-from .router.v1 import router as v1router
-from .router.v2 import router as v2router
+from .router.v1 import V1
+from .router.v2 import V2
 
 # ############
 # FastAPI App
@@ -21,7 +21,10 @@
 
 APP = FastAPI(
     title="Coronavirus Tracker",
-    description="API for tracking the global coronavirus (COVID-19, SARS-CoV-2) outbreak. Project page: https://github.com/ExpDev07/coronavirus-tracker-api.",
+    description=(
+        "API for tracking the global coronavirus (COVID-19, SARS-CoV-2) outbreak."
+        " Project page: https://github.com/ExpDev07/coronavirus-tracker-api."
+    ),
     version="2.0.1",
     docs_url="/",
     redoc_url="/docs",
@@ -36,7 +39,7 @@
     CORSMiddleware, allow_credentials=True, allow_origins=["*"], allow_methods=["*"], allow_headers=["*"],
 )
 
-# TODO this could probably just be a FastAPI dependency.
+
 @APP.middleware("http")
 async def add_datasource(request: Request, call_next):
     """
@@ -64,7 +67,9 @@ async def add_datasource(request: Request, call_next):
 
 
 @APP.exception_handler(pydantic.error_wrappers.ValidationError)
-async def handle_validation_error(request: Request, exc: pydantic.error_wrappers.ValidationError):
+async def handle_validation_error(
+    request: Request, exc: pydantic.error_wrappers.ValidationError
+):  # pylint: disable=unused-argument
     """
     Handles validation errors.
     """
@@ -77,12 +82,12 @@ async def handle_validation_error(request: Request, exc: pydantic.error_wrappers
 
 
 # Include routers.
-APP.include_router(v1router, prefix="", tags=["v1"])
-APP.include_router(v2router, prefix="/v2", tags=["v2"])
+APP.include_router(V1, prefix="", tags=["v1"])
+APP.include_router(V2, prefix="/v2", tags=["v2"])
 
 
 # Running of app.
 if __name__ == "__main__":
     uvicorn.run(
-        "app.main:APP", host="127.0.0.1", port=int(os.getenv("PORT", 5000)), log_level="info",
+        "app.main:APP", host="127.0.0.1", port=int(os.getenv("PORT", "5000")), log_level="info",
     )
diff --git a/app/router/__init__.py b/app/router/__init__.py
index e37fdd9f..4eda6c21 100644
--- a/app/router/__init__.py
+++ b/app/router/__init__.py
@@ -1,5 +1,7 @@
+"""app.router"""
 from fastapi import APIRouter
 
+# pylint: disable=redefined-builtin
 from .v1 import all, confirmed, deaths, recovered
 
 # The routes.
diff --git a/app/router/v1/__init__.py b/app/router/v1/__init__.py
index af9233c5..839bd212 100644
--- a/app/router/v1/__init__.py
+++ b/app/router/v1/__init__.py
@@ -1,3 +1,4 @@
+"""app.router.v1"""
 from fastapi import APIRouter
 
-router = APIRouter()
+V1 = APIRouter()
diff --git a/app/router/v1/all.py b/app/router/v1/all.py
index e528ed5a..b26fe25b 100644
--- a/app/router/v1/all.py
+++ b/app/router/v1/all.py
@@ -1,10 +1,11 @@
+"""app.router.v1.all.py"""
 from ...services.location.jhu import get_category
-from . import router
+from . import V1
 
 
-@router.get("/all")
-def all():
-    # Get all the categories.
+@V1.get("/all")
+def all():  # pylint: disable=redefined-builtin
+    """Get all the categories."""
     confirmed = get_category("confirmed")
     deaths = get_category("deaths")
     recovered = get_category("recovered")
diff --git a/app/router/v1/confirmed.py b/app/router/v1/confirmed.py
index 0a8ab1c3..f3b97523 100644
--- a/app/router/v1/confirmed.py
+++ b/app/router/v1/confirmed.py
@@ -1,9 +1,9 @@
+"""app.router.v1.confirmed.py"""
 from ...services.location.jhu import get_category
-from . import router
+from . import V1
 
 
-@router.get("/confirmed")
+@V1.get("/confirmed")
 def confirmed():
-    confirmed = get_category("confirmed")
-
-    return confirmed
+    """Confirmed cases."""
+    return get_category("confirmed")
diff --git a/app/router/v1/deaths.py b/app/router/v1/deaths.py
index b3d90413..65ed0967 100644
--- a/app/router/v1/deaths.py
+++ b/app/router/v1/deaths.py
@@ -1,9 +1,9 @@
+"""app.router.v1.deaths.py"""
 from ...services.location.jhu import get_category
-from . import router
+from . import V1
 
 
-@router.get("/deaths")
+@V1.get("/deaths")
 def deaths():
-    deaths = get_category("deaths")
-
-    return deaths
+    """Total deaths."""
+    return get_category("deaths")
diff --git a/app/router/v1/recovered.py b/app/router/v1/recovered.py
index e9ae8f72..254823ed 100644
--- a/app/router/v1/recovered.py
+++ b/app/router/v1/recovered.py
@@ -1,9 +1,9 @@
+"""app.router.v1.recovered.py"""
 from ...services.location.jhu import get_category
-from . import router
+from . import V1
 
 
-@router.get("/recovered")
+@V1.get("/recovered")
 def recovered():
-    recovered = get_category("recovered")
-
-    return recovered
+    """Recovered cases."""
+    return get_category("recovered")
diff --git a/app/router/v2/__init__.py b/app/router/v2/__init__.py
index af9233c5..62c31905 100644
--- a/app/router/v2/__init__.py
+++ b/app/router/v2/__init__.py
@@ -1,3 +1,4 @@
+"""app.router.v2"""
 from fastapi import APIRouter
 
-router = APIRouter()
+V2 = APIRouter()
diff --git a/app/router/v2/latest.py b/app/router/v2/latest.py
index 8e2e561b..071c3a22 100644
--- a/app/router/v2/latest.py
+++ b/app/router/v2/latest.py
@@ -1,12 +1,13 @@
+"""app.router.v2.latest.py"""
 from fastapi import Request
 
 from ...enums.sources import Sources
 from ...models.latest import LatestResponse as Latest
-from . import router
+from . import V2
 
 
-@router.get("/latest", response_model=Latest)
-def get_latest(request: Request, source: Sources = "jhu"):
+@V2.get("/latest", response_model=Latest)
+def get_latest(request: Request, source: Sources = "jhu"):  # pylint: disable=unused-argument
     """
     Getting latest amount of total confirmed cases, deaths, and recoveries.
     """
diff --git a/app/router/v2/locations.py b/app/router/v2/locations.py
index 2fde5c9e..815b1eb8 100644
--- a/app/router/v2/locations.py
+++ b/app/router/v2/locations.py
@@ -1,12 +1,14 @@
+"""app.router.v2.locations.py"""
 from fastapi import HTTPException, Request
 
 from ...enums.sources import Sources
 from ...models.location import LocationResponse as Location
 from ...models.location import LocationsResponse as Locations
-from . import router
+from . import V2
 
 
-@router.get("/locations", response_model=Locations, response_model_exclude_unset=True)
+# pylint: disable=unused-argument,too-many-arguments,redefined-builtin
+@V2.get("/locations", response_model=Locations, response_model_exclude_unset=True)
 def get_locations(
     request: Request,
     source: Sources = "jhu",
@@ -53,7 +55,8 @@ def get_locations(
     }
 
 
-@router.get("/locations/{id}", response_model=Location)
+# pylint: disable=invalid-name
+@V2.get("/locations/{id}", response_model=Location)
 def get_location_by_id(request: Request, id: int, source: Sources = "jhu", timelines: bool = True):
     """
     Getting specific location by id.
diff --git a/app/router/v2/sources.py b/app/router/v2/sources.py
index 4ade2fef..ad906e51 100644
--- a/app/router/v2/sources.py
+++ b/app/router/v2/sources.py
@@ -1,10 +1,11 @@
-from ...data import data_sources
-from . import router
+"""app.router.v2.sources.py"""
+from ...data import DATA_SOURCES
+from . import V2
 
 
-@router.get("/sources")
+@V2.get("/sources")
 async def sources():
     """
     Retrieves a list of data-sources that are availble to use.
     """
-    return {"sources": list(data_sources.keys())}
+    return {"sources": list(DATA_SOURCES.keys())}
diff --git a/app/services/location/__init__.py b/app/services/location/__init__.py
index 80b5e05c..404e9f7e 100644
--- a/app/services/location/__init__.py
+++ b/app/services/location/__init__.py
@@ -1,3 +1,4 @@
+"""app.services.location"""
 from abc import ABC, abstractmethod
 
 
@@ -17,7 +18,7 @@ def get_all(self):
         raise NotImplementedError
 
     @abstractmethod
-    def get(self, id):
+    def get(self, id):  # pylint: disable=redefined-builtin,invalid-name
         """
         Gets and returns location with the provided id.
 
diff --git a/app/services/location/csbs.py b/app/services/location/csbs.py
index 6a13f41e..84654963 100644
--- a/app/services/location/csbs.py
+++ b/app/services/location/csbs.py
@@ -1,3 +1,4 @@
+"""app.services.location.csbs.py"""
 import csv
 from datetime import datetime
 
@@ -18,12 +19,12 @@ def get_all(self):
         # Get the locations
         return get_locations()
 
-    def get(self, id):
-        return self.get_all()[id]
+    def get(self, loc_id):  # pylint: disable=arguments-differ
+        return self.get_all()[loc_id]
 
 
 # Base URL for fetching data
-base_url = "https://facts.csbs.org/covid-19/covid19_county.csv"
+BASE_URL = "https://facts.csbs.org/covid-19/covid19_county.csv"
 
 
 @cached(cache=TTLCache(maxsize=1, ttl=3600))
@@ -34,7 +35,7 @@ def get_locations():
     :returns: The locations.
     :rtype: dict
     """
-    request = requests.get(base_url)
+    request = requests.get(BASE_URL)
     text = request.text
 
     data = list(csv.DictReader(text.splitlines()))
@@ -47,11 +48,11 @@ def get_locations():
         county = item["County Name"]
 
         # Ensure country is specified.
-        if county == "Unassigned" or county == "Unknown":
+        if county in {"Unassigned", "Unknown"}:
             continue
 
         # Coordinates.
-        coordinates = Coordinates(item["Latitude"], item["Longitude"])
+        coordinates = Coordinates(item["Latitude"], item["Longitude"])  # pylint: disable=unused-variable
 
         # Date string without "EDT" at end.
         last_update = " ".join(item["Last Update"].split(" ")[0:2])
diff --git a/app/services/location/jhu.py b/app/services/location/jhu.py
index ef99dddc..0f02409f 100644
--- a/app/services/location/jhu.py
+++ b/app/services/location/jhu.py
@@ -1,3 +1,4 @@
+"""app.services.location.jhu.py"""
 import csv
 from datetime import datetime
 
@@ -21,18 +22,16 @@ def get_all(self):
         # Get the locations.
         return get_locations()
 
-    def get(self, id):
+    def get(self, loc_id):  # pylint: disable=arguments-differ
         # Get location at the index equal to provided id.
-        return self.get_all()[id]
+        return self.get_all()[loc_id]
 
 
 # ---------------------------------------------------------------
 
 
-"""
-Base URL for fetching category.
-"""
-base_url = (
+# Base URL for fetching category.
+BASE_URL = (
     "https://raw.githubusercontent.com/CSSEGISandData/2019-nCoV/master/csse_covid_19_data/csse_covid_19_time_series/"
 )
 
@@ -50,7 +49,7 @@ def get_category(category):
     category = category.lower()
 
     # URL to request data from.
-    url = base_url + "time_series_covid19_%s_global.csv" % category
+    url = BASE_URL + "time_series_covid19_%s_global.csv" % category
 
     # Request the data
     request = requests.get(url)
diff --git a/app/timeline.py b/app/timeline.py
index 4916ea2b..0b40d496 100644
--- a/app/timeline.py
+++ b/app/timeline.py
@@ -1,5 +1,5 @@
+"""app.timeline.py"""
 from collections import OrderedDict
-from datetime import datetime
 
 
 class Timeline:
@@ -7,8 +7,8 @@ class Timeline:
     Timeline with history of data.
     """
 
-    def __init__(self, history={}):
-        self.__timeline = history
+    def __init__(self, history=None):
+        self.__timeline = history if history else {}
 
     @property
     def timeline(self):
@@ -26,7 +26,7 @@ def latest(self):
         values = list(self.timeline.values())
 
         # Last item is the latest.
-        if len(values):
+        if values:
             return values[-1] or 0
 
         # Fallback value of 0.
diff --git a/app/utils/countries.py b/app/utils/countries.py
index 6647e679..e0553c64 100644
--- a/app/utils/countries.py
+++ b/app/utils/countries.py
@@ -1,16 +1,16 @@
+"""app.utils.countries.py"""
 import logging
-from itertools import chain
 
 LOGGER = logging.getLogger(__name__)
 
 # Default country code.
-default_country_code = "XX"
+DEFAULT_COUNTRY_CODE = "XX"
 
 # Mapping of country names to alpha-2 codes according to
 # https://en.wikipedia.org/wiki/ISO_3166-1.
 # As a reference see also https://github.com/TakahikoKawasaki/nv-i18n (in Java)
 # fmt: off
-country_name__country_code = {
+COUNTRY_NAME__COUNTRY_CODE = {
     "Afghanistan"                                  : "AF",
     "Åland Islands"                                : "AX",
     "Albania"                                      : "AL",
@@ -363,13 +363,13 @@
 }
 
 # fmt: on
-def country_code(s):
+def country_code(value):
     """
     Return two letter country code (Alpha-2) according to https://en.wikipedia.org/wiki/ISO_3166-1
     Defaults to "XX".
     """
-    country_code = country_name__country_code.get(s, default_country_code)
-    if country_code == default_country_code:
-        LOGGER.warning(f"No country code found for '{s}'. Using '{country_code}'!")
+    code = COUNTRY_NAME__COUNTRY_CODE.get(value, DEFAULT_COUNTRY_CODE)
+    if code == DEFAULT_COUNTRY_CODE:
+        LOGGER.warning(f"No country code found for '{value}'. Using '{code}'!")
 
-    return country_code
+    return code
diff --git a/app/utils/date.py b/app/utils/date.py
index 3a18832e..5a2cc8e5 100644
--- a/app/utils/date.py
+++ b/app/utils/date.py
@@ -1,3 +1,4 @@
+"""app.utils.date.py"""
 from dateutil.parser import parse
 
 
diff --git a/app/utils/populations.py b/app/utils/populations.py
index ea72c334..1d8bd843 100644
--- a/app/utils/populations.py
+++ b/app/utils/populations.py
@@ -1,19 +1,16 @@
+"""app.utils.populations.py"""
 import logging
-from io import BytesIO, StringIO
-from zipfile import ZipFile, ZipInfo
 
 import requests
-from cachetools import TTLCache, cached
-
-from .countries import country_code
 
 LOGGER = logging.getLogger(__name__)
 
 # Fetching of the populations.
 def fetch_populations():
     """
-    Returns a dictionary containing the population of each country fetched from the GeoNames (https://www.geonames.org/).
-    
+    Returns a dictionary containing the population of each country fetched from the GeoNames.
+    https://www.geonames.org/
+
     :returns: The mapping of populations.
     :rtype: dict
     """
@@ -34,7 +31,7 @@ def fetch_populations():
 
 
 # Mapping of alpha-2 codes country codes to population.
-populations = fetch_populations()
+POPULATIONS = fetch_populations()
 
 # Retrieving.
 def country_population(country_code, default=None):
@@ -44,4 +41,4 @@ def country_population(country_code, default=None):
     :returns: The population.
     :rtype: int
     """
-    return populations.get(country_code, default)
+    return POPULATIONS.get(country_code, default)
diff --git a/pylintrc b/pylintrc
index 4db0f41f..af114a33 100644
--- a/pylintrc
+++ b/pylintrc
@@ -3,7 +3,7 @@
 # A comma-separated list of package or module names from where C extensions may
 # be loaded. Extensions are loading into the active Python interpreter and may
 # run arbitrary code.
-extension-pkg-whitelist=
+extension-pkg-whitelist=pydantic
 
 # Add files or directories to the blacklist. They should be base names, not
 # paths.
@@ -139,7 +139,8 @@ disable=print-statement,
         deprecated-sys-function,
         exception-escape,
         comprehension-escape,
-        bad-continuation  # conflicts with black
+        bad-continuation,  # conflicts with black
+        duplicate-code  # turn back on ASAP
 
 # Enable the message, report, category or checker with the given id(s). You can
 # either give multiple identifier separated by comma (,) or put this option
@@ -335,7 +336,7 @@ single-line-if-stmt=no
 
 # Format style used to check logging format string. `old` means using %
 # formatting, `new` is for `{}` formatting,and `fstr` is for f-strings.
-logging-format-style=old
+logging-format-style=fstr
 
 # Logging modules to check that the string format arguments are in logging
 # function parameter format.
@@ -346,8 +347,7 @@ logging-modules=logging
 
 # List of note tags to take in consideration, separated by a comma.
 notes=FIXME,
-      XXX,
-      TODO
+      XXX
 
 
 [SIMILARITIES]
diff --git a/tests/test_countries.py b/tests/test_countries.py
index 2c9ba65e..e28fb469 100644
--- a/tests/test_countries.py
+++ b/tests/test_countries.py
@@ -16,8 +16,8 @@
         ("Bolivia, Plurinational State of", "BO"),
         ("Korea, Democratic People's Republic of", "KP"),
         ("US", "US"),
-        ("BlaBla", countries.default_country_code),
-        ("Others", countries.default_country_code),
+        ("BlaBla", countries.DEFAULT_COUNTRY_CODE),
+        ("Others", countries.DEFAULT_COUNTRY_CODE),
     ],
 )
 def test_countries_country_name__country_code(country_name, expected_country_code):