diff --git a/src/main/java/cc/fascinated/backend/exception/impl/BadRequestException.java b/src/main/java/cc/fascinated/backend/exception/impl/BadRequestException.java
new file mode 100644
index 0000000..e9e0343
--- /dev/null
+++ b/src/main/java/cc/fascinated/backend/exception/impl/BadRequestException.java
@@ -0,0 +1,9 @@
+package cc.fascinated.backend.exception.impl;
+
+import lombok.experimental.StandardException;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@StandardException
+@ResponseStatus(HttpStatus.BAD_REQUEST)
+public class BadRequestException extends RuntimeException { }
diff --git a/src/main/java/cc/fascinated/backend/service/PasteService.java b/src/main/java/cc/fascinated/backend/service/PasteService.java
index da03cb1..c8cb4c8 100644
--- a/src/main/java/cc/fascinated/backend/service/PasteService.java
+++ b/src/main/java/cc/fascinated/backend/service/PasteService.java
@@ -1,5 +1,6 @@
 package cc.fascinated.backend.service;
 
+import cc.fascinated.backend.exception.impl.BadRequestException;
 import cc.fascinated.backend.model.Paste;
 import cc.fascinated.backend.exception.impl.ResourceNotFoundException;
 import cc.fascinated.backend.repository.PasteRepository;
@@ -24,6 +25,12 @@ public class PasteService {
     @Value("${paste.id-length}")
     private int idLength;
 
+    /**
+     * The maximum size of the paste content.
+     */
+    @Value("${paste.upload-size-limit}")
+    private int uploadSizeLimit;
+
     @Autowired
     public PasteService(PasteRepository pasteRepository) {
         this.pasteRepository = pasteRepository;
@@ -36,6 +43,11 @@ public class PasteService {
      * @return The id of the paste.
      */
     public String createPaste(String content) {
+        int length = content.length();
+        if (length > uploadSizeLimit) {
+            throw new BadRequestException("The paste content is too large, the limit is " + uploadSizeLimit + " characters");
+        }
+
         return pasteRepository.save(new Paste(
                 RandomStringUtils.randomAlphabetic(idLength),
                 System.currentTimeMillis(),
diff --git a/src/main/resources/application.yml b/src/main/resources/application.yml
index aad4085..5ff02a7 100644
--- a/src/main/resources/application.yml
+++ b/src/main/resources/application.yml
@@ -23,6 +23,8 @@ spring:
 paste:
   # The length of the ID for the paste
   id-length: 12
+  # The limit of the paste size (in characters)
+  upload-size-limit: 400000
 
 # Set the embedded MongoDB version
 de: