diff --git a/config.d.ts b/config.d.ts
index 8ed1ab4..65c10d1 100644
--- a/config.d.ts
+++ b/config.d.ts
@@ -1,4 +1,4 @@
-import { BindingItem, Variable } from "./src/types/properties/value.ts"
+import { Variable } from "./src/types/properties/value.ts"
 
 export interface RetBindingValue {
 	generate_bindings?: Array<{ source_property_name: string; target_property_name: string }>
@@ -13,6 +13,7 @@ export interface Config {
 		autoEnable?: boolean
 		gdkUserId?: string
 		fixInventoryItemRenderer?: boolean
+		buildFolder?: string
 	}
 	packinfo?: {
 		name?: string
diff --git a/package.json b/package.json
index acfb461..4e83b8a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "asajs",
-	"version": "4.0.7-indev",
+	"version": "4.0.9",
 	"description": "Create your Minecraft JSON-UI resource packs using JavaScript",
 	"keywords": [
 		"Minecraft",
diff --git a/src/compilers/Configuration.ts b/src/compilers/Configuration.ts
index ea74ec8..8cd79ee 100644
--- a/src/compilers/Configuration.ts
+++ b/src/compilers/Configuration.ts
@@ -1,6 +1,6 @@
 import fs from "fs"
 import path from "path"
-// @ts-ignore
+import jsonc from "jsonc-parser"
 import { Config, RetBindingValue } from "../../config.js"
 import { createRequire } from "module"
 
@@ -10,7 +10,11 @@ for (const arg of process.argv) {
 	if (arg.startsWith("--")) options[arg.slice(2)] = true
 }
 
-export const isTestMode = !fs.existsSync("node_modules/asajs")
+export let isTestMode = false
+try {
+	const { name } = jsonc.parse(fs.readFileSync(path.resolve("package.json"), "utf-8"))
+	if (name === "asajs") isTestMode = true
+} catch (error) {}
 
 if (!fs.existsSync("asajs.config.js")) {
 	if (isTestMode) {
@@ -55,6 +59,7 @@ export const config: Config = createRequire(import.meta.url)(path.resolve(proces
 export const isBuildMode = options["build"] ?? config.compiler?.enabled ?? false
 export const isLinkMode = options["link"] ?? config.compiler?.autoImport ?? false
 export const unLinked = options["unlink"] ?? !(config.compiler?.autoImport ?? true)
+export const buildFolder = config.compiler?.buildFolder || "build"
 
 export const bindingFuntions = config.binding_functions
 
diff --git a/src/compilers/PreCompile.ts b/src/compilers/PreCompile.ts
index 48c5694..6dccbe0 100644
--- a/src/compilers/PreCompile.ts
+++ b/src/compilers/PreCompile.ts
@@ -19,12 +19,14 @@ Array.prototype.lastItem = function () {
 }
 
 const now = performance.now()
-type LogType = "INFO"
+type LogType = "INFO" | "WARN"
 
 function TypeHighlight(type: LogType) {
 	switch (type) {
 		case "INFO":
 			return `\x1b[32mINFO\x1b[0m`
+		case "WARN":
+			return `\x1b[33mWARN\x1b[0m`
 		default:
 			return type satisfies never
 	}
diff --git a/src/compilers/ui/buildcache.ts b/src/compilers/ui/buildcache.ts
index 97b1f5b..3216234 100644
--- a/src/compilers/ui/buildcache.ts
+++ b/src/compilers/ui/buildcache.ts
@@ -1,4 +1,5 @@
 import fs from "fs/promises"
+import { buildFolder } from "../Configuration.js"
 
 export class BuildCache {
 	private static queue: Promise<void> = Promise.resolve()
@@ -14,7 +15,9 @@ export class BuildCache {
 	static async get<T = unknown>(key: string): Promise<T | null> {
 		return this.enqueue<T>(async () => {
 			try {
-				return await fs.readFile("build/cache.json", "utf-8").then(data => JSON.parse(data)[key] ?? null)
+				return await fs
+					.readFile(`${buildFolder}/cache.json`, "utf-8")
+					.then(data => JSON.parse(data)[key] ?? null)
 			} catch (error) {
 				return null
 			}
@@ -33,13 +36,13 @@ export class BuildCache {
 			let data: Record<string, any> = {}
 
 			try {
-				data = JSON.parse(await fs.readFile("build/cache.json", "utf-8"))
+				data = JSON.parse(await fs.readFile(`${buildFolder}/cache.json`, "utf-8"))
 			} catch {}
 
 			if (key in data) return data[key]
 			data[key] = outVal
 
-			await fs.writeFile("build/cache.json", JSON.stringify(data), "utf-8")
+			await fs.writeFile(`${buildFolder}/cache.json`, JSON.stringify(data), "utf-8")
 			return outVal
 		})
 	}
@@ -48,15 +51,15 @@ export class BuildCache {
 		return this.enqueue(async () => {
 			try {
 				return fs.writeFile(
-					"build/cache.json",
+					`${buildFolder}/cache.json`,
 					JSON.stringify({
-						...(await fs.readFile("build/cache.json", "utf-8").then(data => JSON.parse(data))),
+						...(await fs.readFile(`${buildFolder}/cache.json`, "utf-8").then(data => JSON.parse(data))),
 						[key]: value,
 					}),
 					"utf-8",
 				)
 			} catch (error) {
-				return fs.writeFile("build/cache.json", JSON.stringify({ [key]: value }), "utf-8")
+				return fs.writeFile(`${buildFolder}/cache.json`, JSON.stringify({ [key]: value }), "utf-8")
 			}
 		})
 	}
diff --git a/src/compilers/ui/builder.ts b/src/compilers/ui/builder.ts
index 65709dc..33fe14b 100644
--- a/src/compilers/ui/builder.ts
+++ b/src/compilers/ui/builder.ts
@@ -1,4 +1,4 @@
-import { config, isBuildMode, isLinkMode, isTestMode, unLinked } from "../Configuration.js"
+import { buildFolder, config, isBuildMode, isLinkMode, isTestMode, unLinked } from "../Configuration.js"
 import { Memory } from "../Memory.js"
 import { createBuildFolder, gamePath, getBuildFolderName, linkToGame, unlink } from "./linker.js"
 import { genManifest, version } from "./manifest.js"
@@ -9,6 +9,7 @@ import { BuildCache } from "./buildcache.js"
 import { disableRSP, enableRSP } from "./installer.js"
 import { Log } from "../PreCompile.js"
 import path from "path"
+import { API_events } from "../../components/API.js"
 
 async function buildUI() {
 	const build = Memory.build()
@@ -20,8 +21,8 @@ async function buildUI() {
 	if (config.global_variables) build.set("ui/_global_variables.json", config.global_variables)
 
 	const out = await Promise.all(
-		build.entries().map(async ([file, value]) => {
-			const outFile = `build/${file}`
+		Array.from(build.entries()).map(async ([file, value]) => {
+			const outFile = `${buildFolder}/${file}`
 			await fs
 				.stat(outFile.split(/\\|\//g).slice(0, -1).join("/"))
 				.catch(async () => await fs.mkdir(outFile.split(/\\|\//g).slice(0, -1).join("/"), { recursive: true }))
@@ -47,23 +48,24 @@ async function buildUI() {
 
 	await Promise.all([
 		fs
-			.writeFile("build/manifest.json", await genManifest(), "utf-8")
-			.then(() => Log("INFO", "build/manifest.json created!")),
+			.writeFile(`${buildFolder}/manifest.json`, await genManifest(), "utf-8")
+			.then(() => Log("INFO", `${buildFolder}/manifest.json created!`)),
 		fs
-			.writeFile("build/.gitignore", [...out, "manifest.json"].join("\n"), "utf-8")
-			.then(() => Log("INFO", "build/.gitignore created!")),
+			.writeFile(`${buildFolder}/.gitignore`, [...out, "manifest.json"].join("\n"), "utf-8")
+			.then(() => Log("INFO", `${buildFolder}/.gitignore created!`)),
 		BuildCache.set("build-files", [...out, "manifest.json"]).then(() => Log("INFO", "build-files set!")),
 		BuildCache.set("version", version).then(() => Log("INFO", "version set!")),
 		fs
-			.stat("build/pack_icon.png")
+			.stat(`${buildFolder}/pack_icon.png`)
 			.catch(() =>
 				fs.copyFile(
 					isTestMode ? "resources/pack_icon.png" : "node_modules/asajs/resources/pack_icon.png",
-					"build/pack_icon.png",
+					`${buildFolder}/pack_icon.png`,
 				),
 			)
-			.then(() => Log("INFO", "build/pack_icon.png copied!")),
-	])
+			.then(() => Log("INFO", `${buildFolder}/pack_icon.png copied!`))
+			.catch(() => Log("WARN", `cannot copy ${buildFolder}/pack_icon.png!`)),
+	]).catch(error => console.error(error))
 
 	return out.length
 }
@@ -93,6 +95,9 @@ if (isBuildMode) {
 					`\x1b[32m"${path.join(gamePath, "development_resource_packs", await getBuildFolderName())}"\x1b[0m`,
 				)
 			console.log("=============================================================")
+
+			// API events
+			API_events.onBuildFinish.forEach(v => v(config))
 		}
 	})
 } else if (isLinkMode) linkToGame()
diff --git a/src/components/API.ts b/src/components/API.ts
new file mode 100644
index 0000000..32b883a
--- /dev/null
+++ b/src/components/API.ts
@@ -0,0 +1,11 @@
+import { Config } from "../../config.js"
+
+export const API_events: { onBuildFinish: ((config: Config) => void)[] } = {
+	onBuildFinish: [],
+}
+
+export const API = {
+	onBuildFinish: function (callback: (config: Config) => void) {
+		API_events.onBuildFinish.push(callback)
+	},
+}
diff --git a/src/index.ts b/src/index.ts
index 5a642f4..239aff6 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -16,3 +16,4 @@ export { ItemAuxID } from "./types/enums/Items.js"
 export { ArrayName, Operation } from "./types/properties/index.js"
 
 export * from "./compilers/bindings/Binary.js"
+export { API } from "./components/API.js"