diff --git a/.dprint.json b/.dprint.json
index 5b5d7f702..840565115 100644
--- a/.dprint.json
+++ b/.dprint.json
@@ -27,7 +27,9 @@
         "licenses.json",
         ".dmypy.json",
         "qt/bundle/PyOxidizer",
-        "target"
+        "target",
+        ".mypy_cache",
+        "extra"
     ],
     "plugins": [
         "https://plugins.dprint.dev/typescript-0.85.1.wasm",
diff --git a/.eslintrc.js b/.eslintrc.js
index e7dd15563..f18b7ea61 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -50,7 +50,7 @@ module.exports = {
         },
     ],
     env: { browser: true },
-    ignorePatterns: ["backend_proto.d.ts", "*.svelte.d.ts", "vendor"],
+    ignorePatterns: ["backend_proto.d.ts", "*.svelte.d.ts", "vendor", "extra/*"],
     globals: {
         globalThis: false,
         NodeListOf: false,
diff --git a/.gitignore b/.gitignore
index 21e7a06b6..68139a32a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,4 @@ node_modules
 .n2_db
 .ninja_log
 .ninja_deps
+/extra
diff --git a/docs/development.md b/docs/development.md
index 1d1ead6b6..3081cbef4 100644
--- a/docs/development.md
+++ b/docs/development.md
@@ -95,6 +95,10 @@ When formatting issues are reported, they can be fixed with
 cargo clippy --fix
 ```
 
+## Excluding your own untracked files from formatting and checks
+
+If you want to add files or folders to the project tree that should be excluded from version tracking and not be matched by formatters and checks, place them in an `extra` folder and they will automatically be ignored.
+
 ## Optimized builds
 
 The `./run` command will create a non-optimized build by default. This is faster
diff --git a/tools/minilints/src/main.rs b/tools/minilints/src/main.rs
index 1f8a206fc..a5d46d4e6 100644
--- a/tools/minilints/src/main.rs
+++ b/tools/minilints/src/main.rs
@@ -40,6 +40,8 @@ const IGNORED_FOLDERS: &[&str] = &[
     "./tools/workspace-hack",
     "./qt/bundle/PyOxidizer",
     "./target",
+    ".mypy_cache",
+    "./extra",
 ];
 
 fn main() -> Result<()> {