diff --git a/src/main/java/aplp/backend/core/common/exception/DomainException.java b/src/main/java/aplp/backend/core/common/exception/DomainException.java
new file mode 100644
index 0000000..8d63959
--- /dev/null
+++ b/src/main/java/aplp/backend/core/common/exception/DomainException.java
@@ -0,0 +1,15 @@
+package aplp.backend.core.common.exception;
+
+public class DomainException extends RuntimeException {
+
+    private final ErrorCode code;
+
+    public DomainException(ErrorCode code, String message) {
+        super(message);
+        this.code = code;
+    }
+
+    public ErrorCode code() {
+        return code;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/aplp/backend/core/common/exception/ErrorCode.java b/src/main/java/aplp/backend/core/common/exception/ErrorCode.java
new file mode 100644
index 0000000..82d3702
--- /dev/null
+++ b/src/main/java/aplp/backend/core/common/exception/ErrorCode.java
@@ -0,0 +1,26 @@
+package aplp.backend.core.common.exception;
+
+public enum ErrorCode {
+
+    INVALID_ARGUMENT(400),
+    VALIDATION_FAILED(400),
+    MALFORMED_REQUEST(400),
+    UNAUTHENTICATED(401),
+    INVALID_CREDENTIALS(401),
+    INVALID_REFRESH_TOKEN(401),
+    ACCESS_DENIED(403),
+    EMAIL_ALREADY_EXISTS(409),
+    USER_NOT_FOUND(404),
+    LEARNER_NOT_FOUND(404),
+    INTERNAL_ERROR(500);
+
+    private final int status;
+
+    ErrorCode(int status) {
+        this.status = status;
+    }
+
+    public int status() {
+        return status;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/aplp/backend/core/common/response/ApiError.java b/src/main/java/aplp/backend/core/common/response/ApiError.java
new file mode 100644
index 0000000..b075558
--- /dev/null
+++ b/src/main/java/aplp/backend/core/common/response/ApiError.java
@@ -0,0 +1,17 @@
+package aplp.backend.core.common.response;
+
+import java.time.Instant;
+
+public record ApiError(
+        Instant timestamp,
+        int status,
+        String error,
+        String code,
+        String message,
+        String traceId
+) {
+
+    public static ApiError of(int status, String error, String code, String message, String traceId) {
+        return new ApiError(Instant.now(), status, error, code, message, traceId);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/aplp/backend/core/common/util/TokenHasher.java b/src/main/java/aplp/backend/core/common/util/TokenHasher.java
new file mode 100644
index 0000000..562e87b
--- /dev/null
+++ b/src/main/java/aplp/backend/core/common/util/TokenHasher.java
@@ -0,0 +1,21 @@
+package aplp.backend.core.common.util;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.HexFormat;
+
+public final class TokenHasher {
+
+    private TokenHasher() {
+    }
+
+    public static String sha256Hex(String value) {
+        try {
+            byte[] digest = MessageDigest.getInstance("SHA-256").digest(value.getBytes(StandardCharsets.UTF_8));
+            return HexFormat.of().formatHex(digest);
+        } catch (NoSuchAlgorithmException e) {
+            throw new IllegalStateException("SHA-256 not available", e);
+        }
+    }
+}
\ No newline at end of file