diff --git a/.changeset/cool-cooks-call.md b/.changeset/cool-cooks-call.md
new file mode 100644
index 0000000..e277a9a
--- /dev/null
+++ b/.changeset/cool-cooks-call.md
@@ -0,0 +1,5 @@
+---
+'@noctisynth/grassator': patch
+---
+
+Extend `String` to `ErrorPayload` to handle default errors
diff --git a/.changeset/early-papayas-melt.md b/.changeset/early-papayas-melt.md
new file mode 100644
index 0000000..a30d891
--- /dev/null
+++ b/.changeset/early-papayas-melt.md
@@ -0,0 +1,5 @@
+---
+'@noctisynth/grassator': patch
+---
+
+Fix set config arg name to `newConfig`
diff --git a/.changeset/hip-sheep-rest.md b/.changeset/hip-sheep-rest.md
new file mode 100644
index 0000000..6c33116
--- /dev/null
+++ b/.changeset/hip-sheep-rest.md
@@ -0,0 +1,6 @@
+---
+'grassator': patch
+'@noctisynth/grassator': patch
+---
+
+Implement config system and auto load on startup
diff --git a/.changeset/itchy-lobsters-laugh.md b/.changeset/itchy-lobsters-laugh.md
new file mode 100644
index 0000000..3c5e54f
--- /dev/null
+++ b/.changeset/itchy-lobsters-laugh.md
@@ -0,0 +1,5 @@
+---
+'@noctisynth/grassator': patch
+---
+
+Add global config proxy object
diff --git a/.changeset/olive-ways-clean.md b/.changeset/olive-ways-clean.md
new file mode 100644
index 0000000..c5d3a5e
--- /dev/null
+++ b/.changeset/olive-ways-clean.md
@@ -0,0 +1,6 @@
+---
+'grassator': patch
+'@noctisynth/grassator': patch
+---
+
+Add config file path to callback data structure
diff --git a/cspell.json b/cspell.json
index 7041076..0123a82 100644
--- a/cspell.json
+++ b/cspell.json
@@ -17,7 +17,8 @@
         "tauri",
         "toastservice",
         "unocss",
-        "unplugin"
+        "unplugin",
+        "usetoast"
     ],
     "ignorePaths": [
         // Tauri files
diff --git a/src-tauri/Cargo.lock b/src-tauri/Cargo.lock
index b3553d8..fd62363 100644
--- a/src-tauri/Cargo.lock
+++ b/src-tauri/Cargo.lock
@@ -275,7 +275,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a969e13a7589e9e3e4207e153bae624ade2b5622fb4684a4923b23ec3d57719"
 dependencies = [
  "serde",
- "toml 0.8.2",
+ "toml 0.8.14",
 ]
 
 [[package]]
@@ -665,7 +665,7 @@ dependencies = [
  "cc",
  "memchr",
  "rustc_version",
- "toml 0.8.2",
+ "toml 0.8.14",
  "vswhom",
  "winreg",
 ]
@@ -1106,7 +1106,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0bb0228f477c0900c880fd78c8759b95c7636dbd7842707f49e132378aa2acdc"
 dependencies = [
  "heck 0.4.1",
- "proc-macro-crate 2.0.2",
+ "proc-macro-crate 2.0.0",
  "proc-macro-error",
  "proc-macro2",
  "quote",
@@ -1150,6 +1150,7 @@ dependencies = [
  "tauri",
  "tauri-build",
  "tauri-plugin-shell",
+ "toml 0.8.14",
 ]
 
 [[package]]
@@ -2421,11 +2422,10 @@ dependencies = [
 
 [[package]]
 name = "proc-macro-crate"
-version = "2.0.2"
+version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b00f26d3400549137f92511a46ac1cd8ce37cb5598a96d382381458b992a5d24"
+checksum = "7e8366a6159044a37876a2b9817124296703c586a5c92e2c53751fa06d8d43e8"
 dependencies = [
- "toml_datetime",
  "toml_edit 0.20.2",
 ]
 
@@ -3282,7 +3282,7 @@ dependencies = [
  "cfg-expr",
  "heck 0.5.0",
  "pkg-config",
- "toml 0.8.2",
+ "toml 0.8.14",
  "version-compare",
 ]
 
@@ -3409,7 +3409,7 @@ dependencies = [
  "serde_json",
  "tauri-utils",
  "tauri-winres",
- "toml 0.8.2",
+ "toml 0.8.14",
  "walkdir",
 ]
 
@@ -3467,7 +3467,7 @@ dependencies = [
  "serde",
  "serde_json",
  "tauri-utils",
- "toml 0.8.2",
+ "toml 0.8.14",
  "walkdir",
 ]
 
@@ -3564,7 +3564,7 @@ dependencies = [
  "serde_with",
  "swift-rs",
  "thiserror",
- "toml 0.8.2",
+ "toml 0.8.14",
  "url",
  "urlpattern",
  "walkdir",
@@ -3749,21 +3749,21 @@ dependencies = [
 
 [[package]]
 name = "toml"
-version = "0.8.2"
+version = "0.8.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "185d8ab0dfbb35cf1399a6344d8484209c088f75f8f68230da55d48d95d43e3d"
+checksum = "6f49eb2ab21d2f26bd6db7bf383edc527a7ebaee412d17af4d40fdccd442f335"
 dependencies = [
  "serde",
  "serde_spanned",
  "toml_datetime",
- "toml_edit 0.20.2",
+ "toml_edit 0.22.15",
 ]
 
 [[package]]
 name = "toml_datetime"
-version = "0.6.3"
+version = "0.6.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7cda73e2f1397b1262d6dfdcef8aafae14d1de7748d66822d3bfeeb6d03e5e4b"
+checksum = "4badfd56924ae69bcc9039335b2e017639ce3f9b001c393c1b2d1ef846ce2cbf"
 dependencies = [
  "serde",
 ]
@@ -3778,7 +3778,7 @@ dependencies = [
  "serde",
  "serde_spanned",
  "toml_datetime",
- "winnow",
+ "winnow 0.5.40",
 ]
 
 [[package]]
@@ -3786,12 +3786,23 @@ name = "toml_edit"
 version = "0.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "396e4d48bbb2b7554c944bde63101b5ae446cff6ec4a24227428f15eb72ef338"
+dependencies = [
+ "indexmap 2.2.6",
+ "toml_datetime",
+ "winnow 0.5.40",
+]
+
+[[package]]
+name = "toml_edit"
+version = "0.22.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d59a3a72298453f564e2b111fa896f8d07fabb36f51f06d7e875fc5e0b5a3ef1"
 dependencies = [
  "indexmap 2.2.6",
  "serde",
  "serde_spanned",
  "toml_datetime",
- "winnow",
+ "winnow 0.6.13",
 ]
 
 [[package]]
@@ -4616,6 +4627,15 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "winnow"
+version = "0.6.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59b5e5f6c299a3c7890b876a2a587f3115162487e704907d9b6cd29473052ba1"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "winreg"
 version = "0.52.0"
diff --git a/src-tauri/Cargo.toml b/src-tauri/Cargo.toml
index c7538f6..b02d3bd 100644
--- a/src-tauri/Cargo.toml
+++ b/src-tauri/Cargo.toml
@@ -20,3 +20,4 @@ tauri-plugin-shell = "2.0.0-beta"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 reqwest = "0.12.5"
+toml = "0.8.14"
diff --git a/src-tauri/src/lib.rs b/src-tauri/src/lib.rs
index 0e2d3e6..0b94fa7 100644
--- a/src-tauri/src/lib.rs
+++ b/src-tauri/src/lib.rs
@@ -1,10 +1,53 @@
+use models::ErrorPayload;
+
 mod models;
 mod state;
 mod utils;
 
 #[tauri::command]
-fn get_config(config: tauri::State<state::Config>) -> Result<state::Config, ()> {
-    Ok(config.inner().clone())
+async fn load_config<R: tauri::Runtime>(
+    app: tauri::AppHandle<R>,
+    config: tauri::State<'_, state::Config>,
+) -> Result<models::ConfigResult, ErrorPayload> {
+    let config_file_path = utils::get_config_path_buf(&app)?;
+    let config_data = if !config_file_path.exists() {
+        let config_data = toml::to_string_pretty(&state::InnerConfig::default()).unwrap();
+        println!("{}", config_data);
+        std::fs::write(&config_file_path, &config_data).unwrap();
+        config_data
+    } else {
+        std::fs::read_to_string(&config_file_path).unwrap()
+    };
+    let inner_config: state::InnerConfig = toml::from_str(&config_data).unwrap();
+    *config.inner().inner.write().await = inner_config.clone();
+    Ok(models::ConfigResult {
+        inner: inner_config,
+        file_path: config_file_path.to_string_lossy().to_string(),
+    })
+}
+
+#[tauri::command]
+async fn get_config(config: tauri::State<'_, state::Config>) -> Result<state::InnerConfig, ()> {
+    Ok(config.inner().inner.read().await.clone())
+}
+
+#[tauri::command]
+async fn set_config<R: tauri::Runtime>(
+    app: tauri::AppHandle<R>,
+    new_config: state::InnerConfig,
+    config: tauri::State<'_, state::Config>,
+) -> Result<models::SetConfigResult, models::ErrorPayload> {
+    let config_file_path = utils::get_config_path_buf(&app)?;
+    let toml = toml::to_string_pretty(&new_config).unwrap();
+    if let Err(e) = std::fs::write(&config_file_path, toml) {
+        return Err(ErrorPayload {
+            message: format!("Failed to update config file: {}", e),
+        });
+    };
+    *config.inner().inner.write().await = new_config;
+    Ok(models::SetConfigResult {
+        config_path: config_file_path.to_string_lossy().to_string(),
+    })
 }
 
 #[tauri::command]
@@ -24,7 +67,7 @@ async fn download_file(
     output: &str,
     config: tauri::State<'_, state::Config>,
 ) -> Result<models::DownloadResult, ()> {
-    match utils::download_file(url, output, &config.inner()).await {
+    match utils::download_file(url, output, &*config.inner().inner.read().await).await {
         Ok(_) => Ok(models::DownloadResult {
             file_path: output.to_string(),
             error: None,
@@ -42,7 +85,9 @@ pub fn run() {
         .manage(state::Config::default())
         .plugin(tauri_plugin_shell::init())
         .invoke_handler(tauri::generate_handler![
+            load_config,
             get_config,
+            set_config,
             get_file_size,
             download_file
         ])
diff --git a/src-tauri/src/models.rs b/src-tauri/src/models.rs
index 9fc1f3a..2c2c5bd 100644
--- a/src-tauri/src/models.rs
+++ b/src-tauri/src/models.rs
@@ -1,5 +1,7 @@
 use serde::{Deserialize, Serialize};
 
+use crate::state::InnerConfig;
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub(crate) struct FileSize {
     pub(crate) size: u64,
@@ -11,3 +13,19 @@ pub(crate) struct DownloadResult {
     pub(crate) file_path: String,
     pub(crate) error: Option<String>,
 }
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub(crate) struct SetConfigResult {
+    pub(crate) config_path: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub(crate) struct ConfigResult {
+    pub(crate) inner: InnerConfig,
+    pub(crate) file_path: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub(crate) struct ErrorPayload {
+    pub(crate) message: String,
+}
diff --git a/src-tauri/src/state.rs b/src-tauri/src/state.rs
index d7dd705..f9345bb 100644
--- a/src-tauri/src/state.rs
+++ b/src-tauri/src/state.rs
@@ -1,16 +1,29 @@
 use serde::{Deserialize, Serialize};
+use tauri::async_runtime::RwLock;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
+pub(crate) struct InnerConfig {
+    pub(crate) preset_file: Option<String>,
+    pub(crate) num_threads: Option<u32>,
+}
+
+impl Default for InnerConfig {
+    fn default() -> Self {
+        Self {
+            preset_file: None,
+            num_threads: Some(12),
+        }
+    }
+}
+
 pub(crate) struct Config {
-    pub(crate) preset_file: String,
-    pub(crate) num_threads: u32,
+    pub(crate) inner: RwLock<InnerConfig>,
 }
 
 impl Default for Config {
     fn default() -> Self {
         Self {
-            preset_file: String::from("presets/default.json"),
-            num_threads: 7,
+            inner: RwLock::new(InnerConfig::default()),
         }
     }
 }
diff --git a/src-tauri/src/utils.rs b/src-tauri/src/utils.rs
index 2897117..8b33cec 100644
--- a/src-tauri/src/utils.rs
+++ b/src-tauri/src/utils.rs
@@ -7,6 +7,7 @@ use std::{
 use reqwest::header::CONTENT_LENGTH;
 use reqwest::header::RANGE;
 use tauri::async_runtime::{spawn, Mutex};
+use tauri::Manager;
 
 pub(crate) async fn get_file_size(url: &str) -> Result<u64, Box<dyn std::error::Error>> {
     let client = reqwest::Client::new();
@@ -23,7 +24,7 @@ pub(crate) async fn get_file_size(url: &str) -> Result<u64, Box<dyn std::error::
 pub(crate) async fn download_file(
     url: &str,
     output_path: &str,
-    config: &crate::state::Config,
+    config: &crate::state::InnerConfig,
 ) -> Result<bool, Box<dyn std::error::Error>> {
     let output = Arc::new(Mutex::new(
         OpenOptions::new()
@@ -33,13 +34,15 @@ pub(crate) async fn download_file(
             .unwrap(),
     ));
 
+    let num_threads = config.num_threads.unwrap_or(12);
+
     let file_size = get_file_size(url).await?;
     let mut handles = Vec::new();
-    let chunk_size = file_size / config.num_threads as u64;
+    let chunk_size = file_size / num_threads as u64;
 
-    for i in 0..config.num_threads {
+    for i in 0..num_threads {
         let start = i as u64 * chunk_size;
-        let end = if i == config.num_threads - 1 {
+        let end = if i == num_threads - 1 {
             file_size - 1
         } else {
             (i as u64 + 1) * chunk_size - 1
@@ -76,3 +79,22 @@ pub(crate) async fn download_chunk(
 
     Ok(())
 }
+
+pub(crate) fn get_config_path_buf<R: tauri::Runtime>(
+    app: &tauri::AppHandle<R>,
+) -> Result<std::path::PathBuf, crate::models::ErrorPayload> {
+    match app.path().app_config_dir() {
+        Ok(mut dir) => {
+            if let Err(e) = std::fs::create_dir_all(&dir) {
+                return Err(crate::models::ErrorPayload {
+                    message: format!("Failed to create app config directory: {}", e),
+                });
+            };
+            dir.push("config.toml");
+            Ok(dir)
+        }
+        Err(e) => Err(crate::models::ErrorPayload {
+            message: format!("Failed to get app config directory: {}", e),
+        }),
+    }
+}
diff --git a/src/App.vue b/src/App.vue
index 3ed4b37..1aa327f 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -1,4 +1,11 @@
-<script setup lang="ts"></script>
+<script setup lang="ts">
+import { onMounted } from 'vue';
+import { loadConfig } from './scripts/config';
+
+onMounted(async () => {
+  await loadConfig();
+});
+</script>
 
 <template>
   <RouterView />
diff --git a/src/scripts/config.ts b/src/scripts/config.ts
new file mode 100644
index 0000000..f51586b
--- /dev/null
+++ b/src/scripts/config.ts
@@ -0,0 +1,29 @@
+import { invoke } from '@tauri-apps/api/core';
+import { Config, ConfigResult, ErrorPayload } from '../types';
+import { useToast } from 'primevue/usetoast';
+
+export let config: Config;
+
+export async function loadConfig(): Promise<ConfigResult> {
+  const toast = useToast();
+  const configResult: ConfigResult = await invoke('load_config');
+  config = new Proxy(configResult.inner, {
+    set: (target, key, value) => {
+      const result = Reflect.set(target, key, value);
+      invoke('set_config', {
+        newConfig: target,
+      }).catch((e: ErrorPayload) => {
+        toast.add({
+          severity: 'error',
+          summary: 'Error',
+          detail: e.message ?? e,
+        });
+      });
+      return result;
+    },
+  });
+  return {
+    file_path: configResult.file_path,
+    inner: config,
+  };
+}
diff --git a/src/types/config.ts b/src/types/config.ts
new file mode 100644
index 0000000..8970326
--- /dev/null
+++ b/src/types/config.ts
@@ -0,0 +1,9 @@
+export interface Config {
+  preset_file?: string;
+  num_threads?: number;
+}
+
+export interface ConfigResult {
+  inner: Config;
+  file_path: string;
+}
diff --git a/src/types/error.ts b/src/types/error.ts
new file mode 100644
index 0000000..964c2d4
--- /dev/null
+++ b/src/types/error.ts
@@ -0,0 +1,3 @@
+export interface ErrorPayload extends String {
+  message: string;
+}
diff --git a/src/types/index.ts b/src/types/index.ts
index 04bca77..a6bae3a 100644
--- a/src/types/index.ts
+++ b/src/types/index.ts
@@ -1 +1,3 @@
 export * from './utils';
+export * from './config';
+export * from './error';
diff --git a/src/views/index.vue b/src/views/index.vue
index c992ca7..dfa3a95 100644
--- a/src/views/index.vue
+++ b/src/views/index.vue
@@ -2,6 +2,7 @@
 import { invoke } from '@tauri-apps/api/core';
 import { onMounted, ref, shallowReactive } from 'vue';
 import { FileSize } from '../types';
+import { config } from '../scripts/config';
 
 const menu = shallowReactive([
   {
@@ -47,11 +48,17 @@ onMounted(async () => {
     url: 'https://freetestdata.com/wp-content/uploads/2021/09/1-MB-DOC.doc',
     output: '1-MB-DOC.doc',
   });
+  // We synchronize the config object with the Rust backend
+  config.num_threads = 12;
+  console.log(config);
+  config.num_threads = 39;
+  console.log(config);
 });
 </script>
 
 <template>
   <main class="h-full w-full">
+    <Toast class="max-w-90%"></Toast>
     <div class="flex flex-col h-full w-full">
       <div
         :class="[
@@ -73,7 +80,6 @@ onMounted(async () => {
             :icon="theme.mode === 'light' ? 'pi pi-sun' : 'pi pi-moon'"
             severity="secondary"
             text
-            disabled
           ></Button>
           <Button
             icon="pi pi-sort-alt"