diff --git a/pom.xml b/pom.xml
index 7d4ce60..1623195 100644
--- a/pom.xml
+++ b/pom.xml
@@ -58,6 +58,7 @@
     <spotless-plugin.version>2.17.6</spotless-plugin.version>
     <surefire-plugin.version>3.0.0-M5</surefire-plugin.version>
 
+    <apiguardian.version>1.1.2</apiguardian.version>
     <errorprone.version>2.10.0</errorprone.version>
     <google-java-format.version>1.13.0</google-java-format.version>
     <jetbrains-annotations.version>22.0.0</jetbrains-annotations.version>
@@ -94,6 +95,12 @@
       <version>${jetbrains-annotations.version}</version>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>org.apiguardian</groupId>
+      <artifactId>apiguardian-api</artifactId>
+      <version>${apiguardian.version}</version>
+      <optional>true</optional>
+    </dependency>
 
     <!-- Testing -->
     <dependency>
diff --git a/src/main/java/eu/mulk/jgvariant/core/Decoder.java b/src/main/java/eu/mulk/jgvariant/core/Decoder.java
index d0c0323..d30366e 100644
--- a/src/main/java/eu/mulk/jgvariant/core/Decoder.java
+++ b/src/main/java/eu/mulk/jgvariant/core/Decoder.java
@@ -12,6 +12,8 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
+import org.apiguardian.api.API;
+import org.apiguardian.api.API.Status;
 import org.jetbrains.annotations.Nullable;
 
 /**
@@ -42,6 +44,7 @@
  * @param <T> the type that the {@link Decoder} can decode.
  */
 @SuppressWarnings("java:S1610")
+@API(status = Status.EXPERIMENTAL)
 public abstract class Decoder<T> {
 
   private Decoder() {}
diff --git a/src/main/java/eu/mulk/jgvariant/core/Signature.java b/src/main/java/eu/mulk/jgvariant/core/Signature.java
index bb03b94..d9de5f1 100644
--- a/src/main/java/eu/mulk/jgvariant/core/Signature.java
+++ b/src/main/java/eu/mulk/jgvariant/core/Signature.java
@@ -6,6 +6,8 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import org.apiguardian.api.API;
+import org.apiguardian.api.API.Status;
 
 /**
  * A GVariant signature string.
@@ -24,6 +26,7 @@
  *       an array of 32-bit integers
  * </dl>
  */
+@API(status = Status.STABLE)
 public final class Signature {
 
   private final String signatureString;
diff --git a/src/main/java/eu/mulk/jgvariant/core/Variant.java b/src/main/java/eu/mulk/jgvariant/core/Variant.java
index 134a5e8..1438d9d 100644
--- a/src/main/java/eu/mulk/jgvariant/core/Variant.java
+++ b/src/main/java/eu/mulk/jgvariant/core/Variant.java
@@ -1,5 +1,8 @@
 package eu.mulk.jgvariant.core;
 
+import org.apiguardian.api.API;
+import org.apiguardian.api.API.Status;
+
 /**
  * A dynamically typed GVariant value carrying a {@link Signature} describing its type.
  *
@@ -23,4 +26,5 @@
  *     Integer}, {@link Long}, {@link String}, {@link java.util.Optional}, {@link java.util.List},
  *     {@link Object[]}, {@link Variant}.
  */
+@API(status = Status.EXPERIMENTAL)
 public record Variant(Signature signature, Object value) {}
diff --git a/src/main/java/module-info.java b/src/main/java/module-info.java
index 39e91b8..c0debad 100644
--- a/src/main/java/module-info.java
+++ b/src/main/java/module-info.java
@@ -8,6 +8,7 @@
 module eu.mulk.jgvariant.core {
   requires com.google.errorprone.annotations;
   requires org.jetbrains.annotations;
+  requires org.apiguardian.api;
 
   exports eu.mulk.jgvariant.core;
 }