diff --git a/README.md b/README.md
index bd26c08a..54878a3c 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ This file stores essential metadata in JSON format. **Make sure you adhere to th
 {
   "title": "Extended Cards",
   "requires-steamodded": true,
-  "category": "Content",
+  "categories": ["Content"],
   "author": "Joe Mama",
   "repo": "https://github.com/joemama/extended-cards",
   "downloadURL": "https://github.com/joemama/extended-cards/releases/latest/extended-cards.tar.gz"
@@ -40,7 +40,7 @@ This file stores essential metadata in JSON format. **Make sure you adhere to th
 
 - **title**: The name of your mod.
 - **requires-steamodded**: If your mod requires the Steamodded mod loader, set this to `true`.
-- **category**: Must be one of `Content`, `Joker`, `Quality of Life`, `Technical`, `Miscellaneous`, `Resource Packs` or `API`.
+- **categories**: Must be of `Content`, `Joker`, `Quality of Life`, `Technical`, `Miscellaneous`, `Resource Packs` or `API`.
 - **author**: Your chosen username or handle.
 - **repo**: A link to your mod’s repository.
 - **downloadURL**: A direct link to the latest version of your released mod. (Can be same as `repo` if no separate download link exists.)
@@ -58,7 +58,7 @@ If included, this image will appear alongside your mod in the index. Maximum and
    Inside it, include:  
    - `description.md` (**required**)  
    - `meta.json` (**required**)  
-   - `thumbnail.png` (optional but recommended)
+   - `thumbnail.jpg` (optional but recommended)
 
 3. **Write Your Mod Description**  
    Use `description.md` to explain what your mod does, key features, and any usage instructions.
diff --git a/mods/Aure@SixSuits/meta.json b/mods/Aure@SixSuits/meta.json
index 8ef76184..f3c8f65e 100644
--- a/mods/Aure@SixSuits/meta.json
+++ b/mods/Aure@SixSuits/meta.json
@@ -1,8 +1,8 @@
 {
     "title": "Six Suits",
     "requires-steamodded": true,
-    "category": "Content",
+    "categories": ["Content"],
     "author": "Aure",
     "repo":"https://github.com/Aurelius7309/SixSuits",
     "downloadURL": "https://github.com/Aurelius7309/SixSuits/archive/refs/heads/master.zip"
-  }
\ No newline at end of file
+  }
diff --git a/mods/InertSteak@Pokermon/meta.json b/mods/InertSteak@Pokermon/meta.json
index 23ed4c45..0f47ab63 100644
--- a/mods/InertSteak@Pokermon/meta.json
+++ b/mods/InertSteak@Pokermon/meta.json
@@ -1,7 +1,7 @@
 {
   "title": "Pokermon",
   "requires-steamodded": true,
-  "category": "Content",
+  "categories": ["Content"],
   "author": "InertSteak",
   "repo":"https://github.com/InertSteak/Pokermon",
   "downloadURL": "https://github.com/InertSteak/Pokermon/archive/refs/tags/2.1.0b.tar.gz"
diff --git a/mods/Larswijn@CardSleeves/meta.json b/mods/Larswijn@CardSleeves/meta.json
index 467997bf..8aa99c90 100644
--- a/mods/Larswijn@CardSleeves/meta.json
+++ b/mods/Larswijn@CardSleeves/meta.json
@@ -1,8 +1,8 @@
 {
   "title": "CardSleeves",
   "requires-steamodded": true,
-  "category": "Content",
+  "categories": ["Content"],
   "author": "Larswijn",
   "repo": "https://github.com/larswijn/CardSleeves",
   "downloadURL": "https://github.com/larswijn/CardSleeves/archive/refs/heads/master.zip"
-}
\ No newline at end of file
+}
diff --git a/mods/Larswijn@CardSleeves/thumbnail.jpg b/mods/Larswijn@CardSleeves/thumbnail.jpg
new file mode 100644
index 00000000..d19d0377
Binary files /dev/null and b/mods/Larswijn@CardSleeves/thumbnail.jpg differ
diff --git a/schema/meta.schema.json b/schema/meta.schema.json
index d52e42b2..97a071c4 100644
--- a/schema/meta.schema.json
+++ b/schema/meta.schema.json
@@ -9,9 +9,14 @@
     "requires-steamodded": {
       "type": "boolean"
     },
-    "category": {
-      "type": "string",
-      "enum": ["Content", "Joker", "Quality of Life", "Technical", "Miscellaneous", "Resource Packs", "API"]
+    "categories": {
+      "type": "array",
+      "items": {
+        "type": "string",
+        "enum": ["Content", "Joker", "Quality of Life", "Technical", "Miscellaneous", "Resource Packs", "API"]
+      },
+      "minItems": 1,
+      "uniqueItems": true
     },
     "author": {
       "type": "string"