diff --git a/today-s-sound/App/TodaySSoundApp.swift b/today-s-sound/App/TodaySSoundApp.swift
index 127aaf5..bb5020b 100644
--- a/today-s-sound/App/TodaySSoundApp.swift
+++ b/today-s-sound/App/TodaySSoundApp.swift
@@ -9,9 +9,18 @@ import SwiftUI
 
 @main
 struct TodaySSoundApp: App {
-  var body: some Scene {
-    WindowGroup {
-      MainView()
+    @StateObject private var session = SessionStore()
+    
+    var body: some Scene {
+        WindowGroup {
+            Group {
+                if session.isRegistered {
+                    MainView()
+                } else {
+                    OnBoardingView()
+                }
+            }
+            .environmentObject(session)
+        }
     }
-  }
 }
diff --git a/today-s-sound/Presentation/Features/OnBoarding/OnBoardingView.swift b/today-s-sound/Presentation/Features/OnBoarding/OnBoardingView.swift
new file mode 100644
index 0000000..6bcd6b6
--- /dev/null
+++ b/today-s-sound/Presentation/Features/OnBoarding/OnBoardingView.swift
@@ -0,0 +1,57 @@
+//
+//  OnBoardingView.swift
+//  today-s-sound
+//
+//  Created by 하승연 on 10/30/25.
+//
+
+import SwiftUI
+
+struct OnBoardingView: View {
+    @EnvironmentObject var session: SessionStore
+    @State private var isLoading = false
+
+    var body: some View {
+        VStack(spacing: 20) {
+            Text("환영합니다 👋")
+                .font(.largeTitle).bold()
+            Text("이 기기를 익명 사용자로 등록하고 서비스를 시작합니다.")
+                .multilineTextAlignment(.center)
+                .foregroundStyle(.secondary)
+
+            if isLoading {
+                ProgressView("등록 중…")
+                    .padding(.top, 8)
+            } else {
+                Button {
+                    Task {
+                        isLoading = true
+                        defer { isLoading = false }
+                        await session.registerIfNeeded()
+                    }
+                } label: {
+                    Text("시작하기")
+                        .frame(maxWidth: .infinity)
+                        .padding()
+                        .background(Color.accentColor)
+                        .foregroundColor(.white)
+                        .clipShape(RoundedRectangle(cornerRadius: 12))
+                }
+                .padding(.top, 12)
+            }
+
+            if let err = session.lastError {
+                Text(err)
+                    .foregroundStyle(.red)
+                    .multilineTextAlignment(.center)
+                    .padding(.top, 8)
+            }
+
+            // 디버그: 생성된 deviceSecret 미리보기(실서비스에서는 숨기기)
+            // if let s = Keychain.getString(for: KeychainKey.deviceSecret) {
+            //     Text("secret: \(s)").font(.footnote).foregroundStyle(.secondary)
+            // }
+        }
+        .padding(24)
+    }
+}
diff --git a/today-s-sound/Services/AppState/SessionStore.swift b/today-s-sound/Services/AppState/SessionStore.swift
new file mode 100644
index 0000000..7ffe585
--- /dev/null
+++ b/today-s-sound/Services/AppState/SessionStore.swift
@@ -0,0 +1,66 @@
+//
+//  SessionStore.swift
+//  today-s-sound
+//
+//  Created by 하승연 on 10/30/25.
+//
+
+import Foundation
+import SwiftUI
+
+@MainActor
+final class SessionStore: ObservableObject {
+    @Published private(set) var userId: String?
+    @Published private(set) var isRegistered: Bool = false
+    @Published var lastError: String?
+
+    private let api = APIClient()
+
+    init() {
+        // 앱 시작 시, 키체인에 저장되어 있으면 로드
+        if let savedId = Keychain.getString(for: KeychainKey.userId) {
+            self.userId = savedId
+            self.isRegistered = true
+        } else {
+            self.isRegistered = false
+        }
+    }
+
+    /// 처음 실행 시 한 번 호출: deviceSecret 생성/보관 → 서버 등록
+    func registerIfNeeded() async {
+        guard !isRegistered else { return }
+
+        // 1) deviceSecret을 키체인에서 찾고, 없으면 생성하여 저장
+        let secret: String = {
+            if let s = Keychain.getString(for: KeychainKey.deviceSecret) { return s }
+            let gen = DeviceSecret.generate()
+            Keychain.setString(gen, for: KeychainKey.deviceSecret)
+            return gen
+        }()
+
+        do {
+            // 2) 서버 호출
+            let body = RegisterAnonymousBody(deviceSecret: secret)
+            typealias Resp = SuccessEnvelope<AnonymousResult>
+            let envelope: Resp = try await api.postJSON(path: "/api/users/anonymous", body: body)
+
+            // 3) user_id 보관
+            Keychain.setString(envelope.result.userId, for: KeychainKey.userId)
+            self.userId = envelope.result.userId
+            self.isRegistered = true
+
+            // (옵션) 서버가 api_key 같은 걸 준다면 저장
+            // if let key = envelope.result.api_key { Keychain.setString(key, for: KeychainKey.apiKey) }
+
+        } catch let APIError.http(_, data) {
+            // 스웨거 에러 포맷 시도 디코딩
+            if let data, let err = try? JSONDecoder().decode(ErrorEnvelope.self, from: data) {
+                lastError = "[\(err.code)] \(err.message)"
+            } else {
+                lastError = "알 수 없는 서버 오류"
+            }
+        } catch {
+            lastError = error.localizedDescription
+        }
+    }
+}
diff --git a/today-s-sound/Services/Config/Enviroment.swift b/today-s-sound/Services/Config/Enviroment.swift
new file mode 100644
index 0000000..2bd4160
--- /dev/null
+++ b/today-s-sound/Services/Config/Enviroment.swift
@@ -0,0 +1,13 @@
+//
+//  Enviroment.swift
+//  today-s-sound
+//
+//  Created by 하승연 on 10/30/25.
+//
+
+import Foundation
+
+enum AppConfig {
+    // 배포/개발 분기 필요하면 Scheme/xcconfig로 주입해도 됨
+    static let baseURL = URL(string: "http://localhost:8080")! // 예: https://api.example.com
+}
diff --git a/today-s-sound/Services/Network/APIClient.swift b/today-s-sound/Services/Network/APIClient.swift
new file mode 100644
index 0000000..ae8e41f
--- /dev/null
+++ b/today-s-sound/Services/Network/APIClient.swift
@@ -0,0 +1,62 @@
+//
+//  APIClient.swift
+//  today-s-sound
+//
+//  Created by 하승연 on 10/30/25.
+//
+
+import Foundation
+
+enum APIError: Error, LocalizedError {
+    case invalidURL
+    case http(status: Int, data: Data?)
+    case decoding(Error)
+    case underlying(Error)
+
+    var errorDescription: String? {
+        switch self {
+        case .invalidURL: return "잘못된 URL"
+        case .http(let s, _): return "서버 오류(\(s))"
+        case .decoding(let e): return "디코딩 오류: \(e.localizedDescription)"
+        case .underlying(let e): return e.localizedDescription
+        }
+    }
+}
+
+final class APIClient {
+    private let baseURL: URL
+    private let session: URLSession
+
+    init(baseURL: URL = AppConfig.baseURL) {
+        self.baseURL = baseURL
+        let cfg = URLSessionConfiguration.default
+        cfg.httpCookieStorage = HTTPCookieStorage.shared
+        cfg.httpShouldSetCookies = true
+        cfg.httpAdditionalHeaders = ["Accept": "application/json",
+                                     "Content-Type": "application/json"]
+        self.session = URLSession(configuration: cfg)
+    }
+
+    func postJSON<Request: Encodable, Response: Decodable>(
+        path: String,
+        body: Request
+    ) async throws -> Response {
+        guard let url = URL(string: path, relativeTo: baseURL) else { throw APIError.invalidURL }
+        var req = URLRequest(url: url)
+        req.httpMethod = "POST"
+        req.httpBody = try JSONEncoder().encode(body)
+
+        let (data, resp) = try await session.data(for: req)  // 요청 보내는 코드
+        print("서버 raw 응답:", String(data: data, encoding: .utf8) ?? "<binary>")
+        guard let http = resp as? HTTPURLResponse else { throw APIError.underlying(URLError(.badServerResponse)) }
+        guard (200..<300).contains(http.statusCode) else {
+            throw APIError.http(status: http.statusCode, data: data)
+        }
+        do {
+            return try JSONDecoder().decode(Response.self, from: data)
+        } catch {
+            // 성공 스펙이 래핑되어 있지 않거나 빈 바디일 수 있으니 필요시 분기
+            throw APIError.decoding(error)
+        }
+    }
+}
diff --git a/today-s-sound/Services/Network/Endpoints/RegisterAnonymous.swift b/today-s-sound/Services/Network/Endpoints/RegisterAnonymous.swift
new file mode 100644
index 0000000..bae95da
--- /dev/null
+++ b/today-s-sound/Services/Network/Endpoints/RegisterAnonymous.swift
@@ -0,0 +1,48 @@
+//
+//  RegisterAnonymous.swift
+//  today-s-sound
+//
+//  Created by 하승연 on 10/30/25.
+//
+
+import Foundation
+import CryptoKit
+
+// 1) Request
+struct RegisterAnonymousBody: Encodable {
+    let deviceSecret: String
+}
+
+// 2) 성공 Response 래퍼
+struct SuccessEnvelope<AnonymousResult: Decodable>: Decodable {
+    let errorCode: String?
+    let message: String
+    let result: AnonymousResult
+}
+
+struct AnonymousResult: Decodable {
+    let userId: String
+    // 서버가 추가로 키 같은 걸 준다면 여기에 옵셔널로:
+    // let api_key: String?
+}
+
+// 3) 에러 Response
+struct ErrorEnvelope: Decodable, Error {
+    let status: Int
+    let code: String
+    let message: String
+}
+
+// 4) deviceSecret 생성 유틸 (32바이트 랜덤 → base64URL)
+enum DeviceSecret {
+    static func generate() -> String {
+        var bytes = [UInt8](repeating: 0, count: 32)
+        _ = SecRandomCopyBytes(kSecRandomDefault, bytes.count, &bytes)
+        // URL-safe base64
+        let data = Data(bytes)
+        return data.base64EncodedString()
+            .replacingOccurrences(of: "+", with: "-")
+            .replacingOccurrences(of: "/", with: "_")
+            .replacingOccurrences(of: "=", with: "")
+    }
+}
diff --git a/today-s-sound/Services/Security/Keychain.swift b/today-s-sound/Services/Security/Keychain.swift
new file mode 100644
index 0000000..9be506a
--- /dev/null
+++ b/today-s-sound/Services/Security/Keychain.swift
@@ -0,0 +1,64 @@
+//
+//  Keychain.swift
+//  today-s-sound
+//
+//  Created by 하승연 on 10/30/25.
+//
+
+import Foundation
+import Security
+
+enum KeychainKey {
+    static let deviceSecret = "device_secret"
+    static let userId = "user_id"
+    static let apiKey = "api_key" // 서버가 추가 키를 준다면 여기에 저장 (옵셔널)
+}
+
+enum Keychain {
+    @discardableResult
+    static func set(_ value: Data, for key: String) -> Bool {
+        let query: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrAccount as String: key,
+            kSecValueData as String: value,
+            kSecAttrAccessible as String: kSecAttrAccessibleAfterFirstUnlock // 앱 재부팅 후에도 접근
+        ]
+        SecItemDelete(query as CFDictionary) // 기존 값 제거
+        let status = SecItemAdd(query as CFDictionary, nil)
+        return status == errSecSuccess
+    }
+
+    static func get(for key: String) -> Data? {
+        let query: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrAccount as String: key,
+            kSecReturnData as String: true,
+            kSecMatchLimit as String: kSecMatchLimitOne
+        ]
+        var item: CFTypeRef?
+        let status = SecItemCopyMatching(query as CFDictionary, &item)
+        guard status == errSecSuccess else { return nil }
+        return (item as? Data)
+    }
+
+    @discardableResult
+    static func delete(for key: String) -> Bool {
+        let query: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrAccount as String: key
+        ]
+        let status = SecItemDelete(query as CFDictionary)
+        return status == errSecSuccess || status == errSecItemNotFound
+    }
+
+    // 문자열 편의
+    @discardableResult
+    static func setString(_ value: String, for key: String) -> Bool {
+        set(Data(value.utf8), for: key)
+    }
+
+    static func getString(for key: String) -> String? {
+        guard let data = get(for: key) else { return nil }
+        return String(data: data, encoding: .utf8)
+    }
+}
diff --git a/today-s-sound/Core/SpeechService.swift b/today-s-sound/Services/SpeechService.swift
similarity index 100%
rename from today-s-sound/Core/SpeechService.swift
rename to today-s-sound/Services/SpeechService.swift