diff --git a/io/src/main/java/org/zhdev/varioutil/config/Config.java b/io/src/main/java/org/zhdev/varioutil/config/Config.java
new file mode 100644
index 0000000..ba5ef14
--- /dev/null
+++ b/io/src/main/java/org/zhdev/varioutil/config/Config.java
@@ -0,0 +1,92 @@
+package org.zhdev.varioutil.config;
+
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public interface Config extends ConfigSection {
+    String getKey();
+
+    void load(Reader reader);
+
+    default void load(InputStream stream) {
+        load(new InputStreamReader(stream, StandardCharsets.UTF_8));
+    }
+
+    default void load(Path path) throws IOException, ConfigException {
+        load(Files.newInputStream(path));
+    }
+
+    default void load(File file) throws IOException, ConfigException {
+        load(file.toPath());
+    }
+
+    default Path load(String pathname) throws ConfigException {
+        Path path = Paths.get(pathname);
+        try {
+            if (Files.exists(path)) load(path);
+        } catch (IOException e) {
+            throw new ConfigException(e);
+        }
+        return path;
+    }
+
+    Path load() throws ConfigException;
+
+    void save(Writer writer);
+
+    default void save(OutputStream stream) {
+        try (OutputStreamWriter writer = new OutputStreamWriter(stream, StandardCharsets.UTF_8)) {
+            save(writer);
+            writer.flush();
+        } catch (IOException e) {
+            throw new ConfigException(e);
+        }
+    }
+
+    default void save(Path path) throws IOException {
+        try (OutputStream stream = Files.newOutputStream(path)) {
+            save(stream);
+        }
+    }
+
+    default void save(File file) throws IOException {
+        save(file.toPath());
+    }
+
+    default Path save(String pathname) throws ConfigException {
+        Path path = Paths.get(pathname);
+        try {
+            if (Files.notExists(path)) {
+                Path parent = path.getParent();
+                if (parent != null) Files.createDirectories(parent);
+                Files.createFile(path);
+            }
+            save(path);
+        } catch (IOException e) {
+            throw new ConfigException(e);
+        }
+        return path;
+    }
+
+    Path save() throws ConfigException;
+
+    default Path saveIfEmpty(String pathname) throws ConfigException {
+        Path path = Paths.get(pathname);
+        try {
+            if (Files.notExists(path) || Files.size(path) == 0) {
+                Path parent = path.getParent();
+                if (parent != null) Files.createDirectories(parent);
+                Files.createFile(path);
+                save(path);
+            }
+        } catch (IOException e) {
+            throw new ConfigException(e);
+        }
+        return path;
+    }
+
+    Path saveIfEmpty() throws ConfigException;
+}