diff --git a/src/main/java/net/knarcraft/knarlib/formatting/StringFormatter.java b/src/main/java/net/knarcraft/knarlib/formatting/StringFormatter.java
index c9daa01..48a9d32 100644
--- a/src/main/java/net/knarcraft/knarlib/formatting/StringFormatter.java
+++ b/src/main/java/net/knarcraft/knarlib/formatting/StringFormatter.java
@@ -28,7 +28,7 @@ public final class StringFormatter {
      * @param pluginName <p>The name of the using plugin (used for the message prefix)</p>
      * @param translator <p>The translator to use for translating messages</p>
      */
-    public StringFormatter(String pluginName, Translator translator) {
+    public StringFormatter(@NotNull String pluginName, @NotNull Translator translator) {
         this.pluginName = pluginName;
         this.translator = translator;
     }
@@ -201,13 +201,9 @@ public final class StringFormatter {
      */
     private String getFormattedMessage(@NotNull String message) {
         message = ColorHelper.translateColorCodes(message, this.colorConversion);
-        if (this.pluginName == null) {
-            return message;
-        } else {
-            String coloredPrefix = ColorHelper.translateColorCodes(namePrefix + ChatColor.RESET +
-                    this.pluginName + ChatColor.RESET + nameSuffix, this.colorConversion);
-            return coloredPrefix + " " + ChatColor.RESET + message;
-        }
+        String coloredPrefix = ColorHelper.translateColorCodes(namePrefix + this.pluginName +
+                nameSuffix, this.colorConversion);
+        return coloredPrefix + " " + ChatColor.RESET + message;
     }
 
 }
diff --git a/src/main/java/net/knarcraft/knarlib/formatting/StringReplacer.java b/src/main/java/net/knarcraft/knarlib/formatting/StringReplacer.java
index c858bb5..9898e9d 100644
--- a/src/main/java/net/knarcraft/knarlib/formatting/StringReplacer.java
+++ b/src/main/java/net/knarcraft/knarlib/formatting/StringReplacer.java
@@ -1,5 +1,7 @@
 package net.knarcraft.knarlib.formatting;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.HashMap;
 import java.util.Map;
 
@@ -25,7 +27,7 @@ public final class StringReplacer {
      *
      * @param replacementInput <p>The input string to replace placeholders for</p>
      */
-    public StringReplacer(String replacementInput) {
+    public StringReplacer(@NotNull String replacementInput) {
         this.replacementInput = replacementInput;
     }
 
@@ -35,7 +37,7 @@ public final class StringReplacer {
      * @param placeholder <p>The placeholder to replace</p>
      * @param value       <p>The replacement value</p>
      */
-    public void add(String placeholder, String value) {
+    public void add(@NotNull String placeholder, @NotNull String value) {
         this.replacements.put(placeholder, value);
     }
 
@@ -44,7 +46,7 @@ public final class StringReplacer {
      *
      * @param placeholder <p>The placeholder to remove</p>
      */
-    public void remove(String placeholder) {
+    public void remove(@NotNull String placeholder) {
         this.replacements.remove(placeholder);
     }
 
@@ -55,7 +57,7 @@ public final class StringReplacer {
      *
      * @return <p>The string with placeholders replaced</p>
      */
-    public String replace() {
+    public @NotNull String replace() {
         if (replacementInput == null) {
             throw new IllegalStateException("This method cannot be run without a defined string");
         }
@@ -68,7 +70,7 @@ public final class StringReplacer {
      * @param input <p>The string to replace placeholders in</p>
      * @return <p>The string with placeholders replaced</p>
      */
-    public String replace(String input) {
+    public @NotNull String replace(@NotNull String input) {
         return StringFormatter.replacePlaceholders(input, replacements.keySet().toArray(new String[0]),
                 replacements.values().toArray(new String[0]));
     }
diff --git a/src/main/java/net/knarcraft/knarlib/formatting/TimeFormatter.java b/src/main/java/net/knarcraft/knarlib/formatting/TimeFormatter.java
index 6689db0..237821d 100644
--- a/src/main/java/net/knarcraft/knarlib/formatting/TimeFormatter.java
+++ b/src/main/java/net/knarcraft/knarlib/formatting/TimeFormatter.java
@@ -1,5 +1,7 @@
 package net.knarcraft.knarlib.formatting;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -28,7 +30,7 @@ public final class TimeFormatter {
      * @param duration   <p>The duration, in seconds, to display</p>
      * @return <p>The string used for displaying this sign's duration</p>
      */
-    public static String getDurationString(Translator translator, long duration) {
+    public static String getDurationString(@NotNull Translator translator, long duration) {
         //Initialize time units once, and only if this method is actually used
         if (sortedUnits == null) {
             initializeUnits(translator);
@@ -76,8 +78,8 @@ public final class TimeFormatter {
      * @param castToInt           <p>Whether to cast the duration to an int</p>
      * @return <p>The formatted duration string</p>
      */
-    private static String formatDurationString(double duration, Translator translator,
-                                               TranslatableMessage translatableMessage, boolean castToInt) {
+    private static String formatDurationString(double duration, @NotNull Translator translator,
+                                               @NotNull TranslatableMessage translatableMessage, boolean castToInt) {
         String durationFormat = translator.getTranslatedMessage(TranslatableTimeUnit.DURATION_FORMAT);
         durationFormat = replacePlaceholder(durationFormat, "{unit}",
                 translator.getTranslatedMessage(translatableMessage));
@@ -88,7 +90,7 @@ public final class TimeFormatter {
     /**
      * Initializes the mapping of available time units for formatting permission sign duration
      */
-    private static void initializeUnits(Translator translator) {
+    private static void initializeUnits(@NotNull Translator translator) {
         //Register each time unit with a registered singular and plural translation
         timeUnits = new HashMap<>();
         registerTimeUnit(translator, 315360000, TranslatableTimeUnit.UNIT_DECADE, TranslatableTimeUnit.UNIT_DECADES);
@@ -102,7 +104,7 @@ public final class TimeFormatter {
                 TranslatableTimeUnit.UNIT_SECONDS);
 
         //As now and seconds are the base units, those must be registered to use getDurationString
-        if (!registeredSeconds || !hasTranslation(translator, TranslatableTimeUnit.UNIT_NOW)) {
+        if (!registeredSeconds || !translator.hasTranslation(TranslatableTimeUnit.UNIT_NOW)) {
             throw new IllegalStateException("A translation is missing for UNIT_SECOND, UNIT_SECONDS or UNIT_NOW");
         }
 
@@ -121,11 +123,12 @@ public final class TimeFormatter {
      * @param plural     <p>The translatable time unit to use for the plural form</p>
      * @return <p>True if the time unit was registered. False if a translation is missing</p>
      */
-    private static boolean registerTimeUnit(Translator translator, double seconds, TranslatableTimeUnit singular,
-                                            TranslatableTimeUnit plural) {
+    private static boolean registerTimeUnit(@NotNull Translator translator, double seconds,
+                                            @NotNull TranslatableTimeUnit singular,
+                                            @NotNull TranslatableTimeUnit plural) {
         String singularTranslation = translator.getTranslatedMessage(singular);
         String pluralTranslation = translator.getTranslatedMessage(plural);
-        if (hasTranslation(translator, singular) && hasTranslation(translator, plural)) {
+        if (translator.hasTranslation(singular) && translator.hasTranslation(plural)) {
             timeUnits.put(seconds, new TranslatableTimeUnit[]{singular, plural});
             return true;
         } else {
@@ -133,16 +136,4 @@ public final class TimeFormatter {
         }
     }
 
-    /**
-     * Checks whether the given translatable message has a registered translation
-     *
-     * @param translator          <p>The translator to check</p>
-     * @param translatableMessage <p>The translatable message to check</p>
-     * @return <p>True if a non-empty translation has been registered</p>
-     */
-    private static boolean hasTranslation(Translator translator, TranslatableMessage translatableMessage) {
-        String translation = translator.getTranslatedMessage(translatableMessage);
-        return translation != null && !translation.isBlank();
-    }
-
 }
diff --git a/src/main/java/net/knarcraft/knarlib/formatting/TranslatableMessage.java b/src/main/java/net/knarcraft/knarlib/formatting/TranslatableMessage.java
index c35a1bc..803f492 100644
--- a/src/main/java/net/knarcraft/knarlib/formatting/TranslatableMessage.java
+++ b/src/main/java/net/knarcraft/knarlib/formatting/TranslatableMessage.java
@@ -1,5 +1,7 @@
 package net.knarcraft.knarlib.formatting;
 
+import org.jetbrains.annotations.NotNull;
+
 /**
  * A message which can be translated
  */
@@ -13,7 +15,7 @@ public interface TranslatableMessage {
      *
      * @return <p>The name of this translatable message</p>
      */
-    String name();
+    @NotNull String name();
 
     /**
      * Gets all translatable messages
@@ -22,6 +24,6 @@ public interface TranslatableMessage {
      *
      * @return <p>All translatable messages</p>
      */
-    TranslatableMessage[] getAllMessages();
+    @NotNull TranslatableMessage[] getAllMessages();
 
 }
diff --git a/src/main/java/net/knarcraft/knarlib/formatting/TranslatableTimeUnit.java b/src/main/java/net/knarcraft/knarlib/formatting/TranslatableTimeUnit.java
index 2e4151d..49a9dd8 100644
--- a/src/main/java/net/knarcraft/knarlib/formatting/TranslatableTimeUnit.java
+++ b/src/main/java/net/knarcraft/knarlib/formatting/TranslatableTimeUnit.java
@@ -1,5 +1,7 @@
 package net.knarcraft.knarlib.formatting;
 
+import org.jetbrains.annotations.NotNull;
+
 /**
  * An enum containing all translatable time units
  *
@@ -101,7 +103,7 @@ public enum TranslatableTimeUnit implements TranslatableMessage {
     ;
 
     @Override
-    public TranslatableMessage[] getAllMessages() {
+    public @NotNull TranslatableMessage[] getAllMessages() {
         return TranslatableTimeUnit.values();
     }
 
diff --git a/src/main/java/net/knarcraft/knarlib/formatting/Translator.java b/src/main/java/net/knarcraft/knarlib/formatting/Translator.java
index 858910d..3d23c08 100644
--- a/src/main/java/net/knarcraft/knarlib/formatting/Translator.java
+++ b/src/main/java/net/knarcraft/knarlib/formatting/Translator.java
@@ -5,12 +5,12 @@ import net.knarcraft.knarlib.util.ColorHelper;
 import net.knarcraft.knarlib.util.FileHelper;
 import org.bukkit.Bukkit;
 import org.bukkit.configuration.file.YamlConfiguration;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.BufferedReader;
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.FileNotFoundException;
-import java.io.InputStreamReader;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -41,7 +41,7 @@ public final class Translator {
      *
      * @param translatableMessage <p>A translatable message in the category to register</p>
      */
-    public void registerMessageCategory(TranslatableMessage translatableMessage) {
+    public void registerMessageCategory(@NotNull TranslatableMessage translatableMessage) {
         messageCategories.add(translatableMessage);
     }
 
@@ -54,12 +54,8 @@ public final class Translator {
      *
      * @param colorConversion <p>The color conversion to be used</p>
      */
-    public void setColorConversion(ColorConversion colorConversion) {
-        if (colorConversion != null) {
-            this.colorConversion = colorConversion;
-        } else {
-            throw new IllegalArgumentException("Color conversion cannot be null");
-        }
+    public void setColorConversion(@NotNull ColorConversion colorConversion) {
+        this.colorConversion = colorConversion;
     }
 
     /**
@@ -69,7 +65,8 @@ public final class Translator {
      * @param fallbackLanguage <p>The default language to fall back on in the case of missing translations</p>
      * @param selectedLanguage <p>The currently selected language</p>
      */
-    public void loadLanguages(File dataFolder, String fallbackLanguage, String selectedLanguage) {
+    public void loadLanguages(@NotNull File dataFolder, @NotNull String fallbackLanguage,
+                              @NotNull String selectedLanguage) {
         backupTranslatedMessages = loadTranslatedMessages(fallbackLanguage);
         translatedMessages = loadCustomTranslatedMessages(dataFolder, selectedLanguage);
         if (translatedMessages == null) {
@@ -77,13 +74,24 @@ public final class Translator {
         }
     }
 
+    /**
+     * Checks whether the given translatable message has a translation
+     *
+     * @param translatableMessage <p>The translatable message to check</p>
+     * @return <p>True if the message has a translation</p>
+     */
+    public boolean hasTranslation(@NotNull TranslatableMessage translatableMessage) {
+        return backupTranslatedMessages.containsKey(translatableMessage) &&
+                !backupTranslatedMessages.get(translatableMessage).isBlank();
+    }
+
     /**
      * Gets a translated version of the given translatable message
      *
      * @param translatableMessage <p>The message to translate</p>
      * @return <p>The translated message</p>
      */
-    public String getTranslatedMessage(TranslatableMessage translatableMessage) {
+    public @NotNull String getTranslatedMessage(@NotNull TranslatableMessage translatableMessage) {
         if (translatedMessages == null) {
             return "Translated strings not loaded";
         }
@@ -104,7 +112,7 @@ public final class Translator {
      * @param language <p>The language chosen by the user</p>
      * @return <p>A mapping of all strings for the given language</p>
      */
-    public Map<TranslatableMessage, String> loadTranslatedMessages(String language) {
+    public @Nullable Map<TranslatableMessage, String> loadTranslatedMessages(@NotNull String language) {
         try {
             BufferedReader reader = FileHelper.getBufferedReaderForInternalFile("/strings.yml");
             return loadTranslatableMessages(language, reader);
@@ -121,10 +129,8 @@ public final class Translator {
      * @param language   <p>The selected language</p>
      * @return <p>The loaded translated strings, or null if no custom language file exists</p>
      */
-    public Map<TranslatableMessage, String> loadCustomTranslatedMessages(File dataFolder, String language) {
-        if (dataFolder == null) {
-            return null;
-        }
+    public @Nullable Map<TranslatableMessage, String> loadCustomTranslatedMessages(@NotNull File dataFolder,
+                                                                                   @NotNull String language) {
         File strings = new File(dataFolder, "strings.yml");
         if (!strings.exists()) {
             Bukkit.getLogger().log(Level.FINEST, "Strings file not found");
@@ -133,9 +139,9 @@ public final class Translator {
 
         try {
             Bukkit.getLogger().log(Level.INFO, "Loading custom strings...");
-            return loadTranslatableMessages(language, new BufferedReader(new InputStreamReader(
-                    new FileInputStream(strings))));
-        } catch (FileNotFoundException e) {
+            return loadTranslatableMessages(language,
+                    FileHelper.getBufferedReaderFromString(strings.toPath().toString()));
+        } catch (FileNotFoundException exception) {
             Bukkit.getLogger().log(Level.WARNING, "Unable to load custom messages");
             return null;
         }
@@ -148,7 +154,8 @@ public final class Translator {
      * @param reader   <p>The buffered reader to read from</p>
      * @return <p>The loaded translated strings</p>
      */
-    private Map<TranslatableMessage, String> loadTranslatableMessages(String language, BufferedReader reader) {
+    private @NotNull Map<TranslatableMessage, String> loadTranslatableMessages(@NotNull String language,
+                                                                               @NotNull BufferedReader reader) {
         Map<TranslatableMessage, String> translatedMessages = new HashMap<>();
         YamlConfiguration configuration = YamlConfiguration.loadConfiguration(reader);
 
diff --git a/src/main/java/net/knarcraft/knarlib/particle/ParticleConfig.java b/src/main/java/net/knarcraft/knarlib/particle/ParticleConfig.java
index 29a1cf3..c522dd2 100644
--- a/src/main/java/net/knarcraft/knarlib/particle/ParticleConfig.java
+++ b/src/main/java/net/knarcraft/knarlib/particle/ParticleConfig.java
@@ -70,8 +70,9 @@ public final class ParticleConfig {
      * @param offsetZ         <p>The z-offset/spread of the spawned particles</p>
      * @param extra           <p>Extra data for the particle. Usage depends on the particle type.</p>
      */
-    public ParticleConfig(ParticleMode particleMode, Particle particleType, int particleAmount, double particleDensity,
-                          double heightOffset, double offsetX, double offsetY, double offsetZ, double extra) {
+    public ParticleConfig(@NotNull ParticleMode particleMode, @NotNull Particle particleType, int particleAmount,
+                          double particleDensity, double heightOffset, double offsetX, double offsetY, double offsetZ,
+                          double extra) {
         this.particleMode = particleMode;
         this.particleType = particleType;
         this.particleAmount = particleAmount;
@@ -88,7 +89,7 @@ public final class ParticleConfig {
      *
      * @return <p>The particle mode</p>
      */
-    public ParticleMode getParticleMode() {
+    public @NotNull ParticleMode getParticleMode() {
         return particleMode;
     }
 
@@ -97,7 +98,7 @@ public final class ParticleConfig {
      *
      * @return <p>The particle type</p>
      */
-    public Particle getParticleType() {
+    public @NotNull Particle getParticleType() {
         return particleType;
     }
 
diff --git a/src/main/java/net/knarcraft/knarlib/particle/ParticleSpawner.java b/src/main/java/net/knarcraft/knarlib/particle/ParticleSpawner.java
index 5775df9..8faa133 100644
--- a/src/main/java/net/knarcraft/knarlib/particle/ParticleSpawner.java
+++ b/src/main/java/net/knarcraft/knarlib/particle/ParticleSpawner.java
@@ -69,7 +69,7 @@ public final class ParticleSpawner implements Runnable {
      *
      * @return <p>The id used for stored calculations</p>
      */
-    public UUID getStoredCalculationId() {
+    public @NotNull UUID getStoredCalculationId() {
         return this.storedCalculationId;
     }
 
@@ -131,7 +131,7 @@ public final class ParticleSpawner implements Runnable {
      *
      * @return <p>The particle config to use</p>
      */
-    private ParticleConfig getParticleConfig() {
+    private @NotNull ParticleConfig getParticleConfig() {
         ParticleConfig materialConfig = this.materialConfigs.get(processingBlock.getType());
         if (materialConfig != null) {
             return materialConfig;
diff --git a/src/main/java/net/knarcraft/knarlib/particle/ParticleTrailSpawner.java b/src/main/java/net/knarcraft/knarlib/particle/ParticleTrailSpawner.java
index d36eead..19c2275 100644
--- a/src/main/java/net/knarcraft/knarlib/particle/ParticleTrailSpawner.java
+++ b/src/main/java/net/knarcraft/knarlib/particle/ParticleTrailSpawner.java
@@ -85,7 +85,7 @@ public final class ParticleTrailSpawner implements Runnable {
      *
      * @param playerId <p>The id of the player to remove the trail for</p>
      */
-    public void removeTrail(UUID playerId) {
+    public void removeTrail(@NotNull UUID playerId) {
         this.playersWithTrails.remove(playerId);
         this.playerParticles.remove(playerId);
     }
@@ -95,7 +95,7 @@ public final class ParticleTrailSpawner implements Runnable {
      *
      * @param playerId <p>The id of the player to add the trail to</p>
      */
-    public void startTrail(UUID playerId) {
+    public void startTrail(@NotNull UUID playerId) {
         this.playerParticles.put(playerId, randomParticle());
         this.playersWithTrails.add(playerId);
     }
@@ -105,7 +105,7 @@ public final class ParticleTrailSpawner implements Runnable {
      *
      * @return <p>A random particle</p>
      */
-    private Particle randomParticle() {
+    private @NotNull Particle randomParticle() {
         Particle spawnParticle = null;
         while (spawnParticle == null || spawnParticle.getDataType() != Void.class) {
             spawnParticle = randomTrailTypes.get(random.nextInt(randomTrailTypes.size()));
diff --git a/src/main/java/net/knarcraft/knarlib/util/ColorHelper.java b/src/main/java/net/knarcraft/knarlib/util/ColorHelper.java
index 0c8cf7e..f5793bd 100644
--- a/src/main/java/net/knarcraft/knarlib/util/ColorHelper.java
+++ b/src/main/java/net/knarcraft/knarlib/util/ColorHelper.java
@@ -3,6 +3,7 @@ package net.knarcraft.knarlib.util;
 import net.knarcraft.knarlib.property.ColorConversion;
 import net.md_5.bungee.api.ChatColor;
 import org.bukkit.Color;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -25,7 +26,7 @@ public final class ColorHelper {
      * @param color <p>The color to invert</p>
      * @return <p>The inverted color</p>
      */
-    public static Color invert(Color color) {
+    public static @NotNull Color invert(@NotNull Color color) {
         return color.setRed(255 - color.getRed()).setGreen(255 - color.getGreen()).setBlue(255 - color.getBlue());
     }
 
@@ -35,7 +36,7 @@ public final class ColorHelper {
      * @param color <p>The color to convert into a chat color</p>
      * @return <p>The resulting chat color</p>
      */
-    public static ChatColor fromColor(Color color) {
+    public static @NotNull ChatColor fromColor(@NotNull Color color) {
         return ChatColor.of(String.format("#%02X%02X%02X", color.getRed(), color.getGreen(), color.getBlue()));
     }
 
@@ -58,7 +59,7 @@ public final class ColorHelper {
      * @param colorConversion <p>The type of color conversion to apply before stripping</p>
      * @return <p>The message without color codes</p>
      */
-    public static String stripColorCodes(String message, ColorConversion colorConversion) {
+    public static @NotNull String stripColorCodes(@NotNull String message, @NotNull ColorConversion colorConversion) {
         return ChatColor.stripColor(translateColorCodes(message, colorConversion));
     }
 
@@ -69,7 +70,7 @@ public final class ColorHelper {
      * @param colorConversion <p>The type of color conversion to apply</p>
      * @return <p>The string with color codes applied</p>
      */
-    public static String translateColorCodes(String message, ColorConversion colorConversion) {
+    public static @NotNull String translateColorCodes(@NotNull String message, @NotNull ColorConversion colorConversion) {
         return switch (colorConversion) {
             case NONE -> message;
             case NORMAL -> ChatColor.translateAlternateColorCodes('&', message);
@@ -85,7 +86,7 @@ public final class ColorHelper {
      * @param onlyRGB <p>Whether to only convert RGB (hexadecimal) color codes. If false, &[a-f0-9] will be converted as well.</p>
      * @return <p>The message with color codes translated</p>
      */
-    private static String translateAllColorCodes(String message, boolean onlyRGB) {
+    private static @NotNull String translateAllColorCodes(@NotNull String message, boolean onlyRGB) {
         if (!onlyRGB) {
             message = ChatColor.translateAlternateColorCodes('&', message);
         }
diff --git a/src/main/java/net/knarcraft/knarlib/util/FileHelper.java b/src/main/java/net/knarcraft/knarlib/util/FileHelper.java
index 89556d8..481eed2 100644
--- a/src/main/java/net/knarcraft/knarlib/util/FileHelper.java
+++ b/src/main/java/net/knarcraft/knarlib/util/FileHelper.java
@@ -1,6 +1,8 @@
 package net.knarcraft.knarlib.util;
 
 import net.knarcraft.knarlib.property.ColorConversion;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.BufferedReader;
 import java.io.BufferedWriter;
@@ -33,7 +35,7 @@ public final class FileHelper {
      * @return <p>A buffered read for reading the file</p>
      * @throws FileNotFoundException <p>If unable to get an input stream for the given file</p>
      */
-    public static BufferedReader getBufferedReaderForInternalFile(String file) throws FileNotFoundException {
+    public static @NotNull BufferedReader getBufferedReaderForInternalFile(@NotNull String file) throws FileNotFoundException {
         InputStream inputStream = getInputStreamForInternalFile(file);
         if (inputStream == null) {
             throw new FileNotFoundException("Unable to read the given file");
@@ -50,7 +52,7 @@ public final class FileHelper {
      * @param file <p>The file to read</p>
      * @return <p>An input stream for the file</p>
      */
-    public static InputStream getInputStreamForInternalFile(String file) {
+    public static @Nullable InputStream getInputStreamForInternalFile(@NotNull String file) {
         return FileHelper.class.getResourceAsStream(file);
     }
 
@@ -61,7 +63,7 @@ public final class FileHelper {
      * @return <p>A buffered reader reading the file</p>
      * @throws FileNotFoundException <p>If the given file does not exist</p>
      */
-    public static BufferedReader getBufferedReaderFromString(String file) throws FileNotFoundException {
+    public static @NotNull BufferedReader getBufferedReaderFromString(@NotNull String file) throws FileNotFoundException {
         FileInputStream fileInputStream = new FileInputStream(file);
         return getBufferedReaderFromInputStream(fileInputStream);
     }
@@ -72,7 +74,7 @@ public final class FileHelper {
      * @param inputStream <p>The input stream to read</p>
      * @return <p>A buffered reader reading the input stream</p>
      */
-    public static BufferedReader getBufferedReaderFromInputStream(InputStream inputStream) {
+    public static @NotNull BufferedReader getBufferedReaderFromInputStream(@NotNull InputStream inputStream) {
         InputStreamReader inputStreamReader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
         return new BufferedReader(inputStreamReader);
     }
@@ -84,7 +86,7 @@ public final class FileHelper {
      * @return <p>A buffered writer writing to the file</p>
      * @throws FileNotFoundException <p>If the file does not exist</p>
      */
-    public static BufferedWriter getBufferedWriterFromString(String file) throws FileNotFoundException {
+    public static @NotNull BufferedWriter getBufferedWriterFromString(@NotNull String file) throws FileNotFoundException {
         FileOutputStream fileOutputStream = new FileOutputStream(file);
         OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream, StandardCharsets.UTF_8);
         return new BufferedWriter(outputStreamWriter);
@@ -99,8 +101,9 @@ public final class FileHelper {
      * @return <p>A map containing the read pairs</p>
      * @throws IOException <p>If unable to read from the stream</p>
      */
-    public static Map<String, String> readKeyValuePairs(BufferedReader bufferedReader, String separator,
-                                                        ColorConversion colorConversion) throws IOException {
+    public static Map<String, String> readKeyValuePairs(@NotNull BufferedReader bufferedReader,
+                                                        @NotNull String separator,
+                                                        @NotNull ColorConversion colorConversion) throws IOException {
         Map<String, String> readPairs = new HashMap<>();
 
         String line = bufferedReader.readLine();
@@ -136,7 +139,7 @@ public final class FileHelper {
      * @param string <p>The string to remove the BOM from</p>
      * @return <p>A string guaranteed without a BOM</p>
      */
-    private static String removeUTF8BOM(String string) {
+    private static @NotNull String removeUTF8BOM(@NotNull String string) {
         String UTF8_BOM = "\uFEFF";
         if (string.startsWith(UTF8_BOM)) {
             string = string.substring(1);
diff --git a/src/main/java/net/knarcraft/knarlib/util/ParticleHelper.java b/src/main/java/net/knarcraft/knarlib/util/ParticleHelper.java
index 0ad6dc6..3763060 100644
--- a/src/main/java/net/knarcraft/knarlib/util/ParticleHelper.java
+++ b/src/main/java/net/knarcraft/knarlib/util/ParticleHelper.java
@@ -229,7 +229,7 @@ public final class ParticleHelper {
      * @param block <p>The block to check</p>
      * @return <p>The height of the block</p>
      */
-    public static double getBlockHeight(Block block) {
+    public static double getBlockHeight(@NotNull Block block) {
         double maxY = 0;
         for (BoundingBox boundingBox : block.getCollisionShape().getBoundingBoxes()) {
             if (boundingBox.getMaxY() > maxY) {
diff --git a/src/main/java/net/knarcraft/knarlib/util/TabCompletionHelper.java b/src/main/java/net/knarcraft/knarlib/util/TabCompletionHelper.java
index 69b3988..795910d 100644
--- a/src/main/java/net/knarcraft/knarlib/util/TabCompletionHelper.java
+++ b/src/main/java/net/knarcraft/knarlib/util/TabCompletionHelper.java
@@ -1,5 +1,7 @@
 package net.knarcraft.knarlib.util;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -19,7 +21,7 @@ public final class TabCompletionHelper {
      * @param typedText <p>The text the player has started typing</p>
      * @return <p>The given string values that contain the player's typed text</p>
      */
-    public static List<String> filterMatchingContains(List<String> values, String typedText) {
+    public static @NotNull List<String> filterMatchingContains(@NotNull List<String> values, @NotNull String typedText) {
         List<String> configValues = new ArrayList<>();
         for (String value : values) {
             if (value.toLowerCase().contains(typedText.toLowerCase())) {
@@ -36,7 +38,7 @@ public final class TabCompletionHelper {
      * @param typedText <p>The text the player has started typing</p>
      * @return <p>The given string values that start with the player's typed text</p>
      */
-    public static List<String> filterMatchingStartsWith(List<String> values, String typedText) {
+    public static @NotNull List<String> filterMatchingStartsWith(@NotNull List<String> values, @NotNull String typedText) {
         List<String> configValues = new ArrayList<>();
         for (String value : values) {
             if (value.toLowerCase().startsWith(typedText.toLowerCase())) {
diff --git a/src/main/java/net/knarcraft/knarlib/util/UpdateChecker.java b/src/main/java/net/knarcraft/knarlib/util/UpdateChecker.java
index edc1698..8bf43e7 100644
--- a/src/main/java/net/knarcraft/knarlib/util/UpdateChecker.java
+++ b/src/main/java/net/knarcraft/knarlib/util/UpdateChecker.java
@@ -2,6 +2,8 @@ package net.knarcraft.knarlib.util;
 
 import org.bukkit.plugin.Plugin;
 import org.bukkit.scheduler.BukkitScheduler;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -33,8 +35,9 @@ public final class UpdateChecker {
      * @param getVersionSupplier <p>The supplier used to get the current plugin version</p>
      * @param setVersionMethod   <p>A method to call with the new version as an argument. Can be used to alert admins about an available update or similar.</p>
      */
-    public static void checkForUpdate(Plugin plugin, String apiResourceURL, Supplier<String> getVersionSupplier,
-                                      Consumer<String> setVersionMethod) {
+    public static void checkForUpdate(@NotNull Plugin plugin, @NotNull String apiResourceURL,
+                                      @NotNull Supplier<String> getVersionSupplier,
+                                      @NotNull Consumer<String> setVersionMethod) {
         BukkitScheduler scheduler = plugin.getServer().getScheduler();
         scheduler.runTaskAsynchronously(plugin, () -> UpdateChecker.queryAPI(plugin, apiResourceURL, getVersionSupplier,
                 setVersionMethod));
@@ -48,8 +51,9 @@ public final class UpdateChecker {
      * @param getVersionMethod <p>The supplier used to get the current plugin version</p>
      * @param setVersionMethod <p>A method to call with the new version as an argument. Can be used to alert admins about an available update or similar.</p>
      */
-    private static void queryAPI(Plugin plugin, String APIResourceURL, Supplier<String> getVersionMethod,
-                                 Consumer<String> setVersionMethod) {
+    private static void queryAPI(@NotNull Plugin plugin, @NotNull String APIResourceURL,
+                                 @NotNull Supplier<String> getVersionMethod,
+                                 @Nullable Consumer<String> setVersionMethod) {
         try {
             InputStream inputStream = new URL(APIResourceURL).openStream();
             BufferedReader reader = FileHelper.getBufferedReaderFromInputStream(inputStream);
@@ -77,7 +81,7 @@ public final class UpdateChecker {
      * @param oldVersion <p>The old (current) plugin version</p>
      * @return <p>The string to display</p>
      */
-    public static String getUpdateAvailableString(String newVersion, String oldVersion) {
+    public static @NotNull String getUpdateAvailableString(@NotNull String newVersion, @NotNull String oldVersion) {
         return String.format(updateNotice, newVersion, oldVersion);
     }
 
@@ -88,7 +92,7 @@ public final class UpdateChecker {
      * @param newVersion <p>The new version to check</p>
      * @return <p>True if the new version is higher than the old one</p>
      */
-    public static boolean isVersionHigher(String oldVersion, String newVersion) {
+    public static boolean isVersionHigher(@NotNull String oldVersion, @NotNull String newVersion) {
         oldVersion = removeNonNumericCharacters(oldVersion);
         newVersion = removeNonNumericCharacters(newVersion);
         String[] oldVersionParts = oldVersion.split("\\.");
@@ -110,7 +114,7 @@ public final class UpdateChecker {
      * @param versionString <p>The version string to clean</p>
      * @return <p>The string with non-numeric characters replaced</p>
      */
-    private static String removeNonNumericCharacters(String versionString) {
+    private static @NotNull String removeNonNumericCharacters(@NotNull String versionString) {
         return versionString.replaceAll("[^0-9.]", "");
     }