diff --git a/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/resumableupload/ResumableUploadProgressListener.java b/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/resumableupload/ResumableUploadProgressListener.java
new file mode 100644
index 000000000000..cb9038b79d4b
--- /dev/null
+++ b/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/resumableupload/ResumableUploadProgressListener.java
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.resumableupload;
+
+import com.google.api.core.BetaApi;
+import org.jspecify.annotations.NullMarked;
+
+/** A callback listener for observing the progress and state transitions of a resumable upload. */
+@BetaApi
+@FunctionalInterface
+@NullMarked
+public interface ResumableUploadProgressListener {
+
+  /**
+   * Invoked when upload progress or state changes.
+   *
+   * @param status the current status snapshot of the upload
+   */
+  void onProgress(ResumableUploadStatus status);
+}
diff --git a/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/resumableupload/ResumableUploadStatus.java b/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/resumableupload/ResumableUploadStatus.java
new file mode 100644
index 000000000000..6a283723a4f2
--- /dev/null
+++ b/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/resumableupload/ResumableUploadStatus.java
@@ -0,0 +1,152 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.resumableupload;
+
+import com.google.api.core.BetaApi;
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Preconditions;
+import org.jspecify.annotations.NullMarked;
+
+/** Status snapshot of an ongoing resumable upload session. */
+@BetaApi
+@NullMarked
+@AutoValue
+public abstract class ResumableUploadStatus {
+
+  /** The state of the resumable upload session. */
+  public enum State {
+    /** The upload session was successfully initiated with the server. */
+    STARTED,
+
+    /** A data chunk was successfully uploaded to the server. */
+    UPLOADING,
+
+    /** A recoverable error occurred; the client is initiating recovery. */
+    RECOVERING,
+
+    /** A status query succeeded and the stream offset was reconciled. */
+    OFFSET_RECEIVED,
+
+    /** The final chunk was accepted and the upload session is complete. */
+    FINALIZED
+  }
+
+  /** Returns the negotiated upload session URI. */
+  public abstract String getUploadUrl();
+
+  /** Returns the number of bytes successfully uploaded to the server so far. */
+  public abstract long getBytesUploaded();
+
+  /** Returns the total size of the upload payload in bytes, or -1 if unknown. */
+  public abstract long getTotalBytes();
+
+  /** Returns the current state of the upload session. */
+  public abstract State getState();
+
+  /** Returns whether the total upload size is unknown (e.g. streaming upload). */
+  public boolean isIndeterminate() {
+    return getTotalBytes() == -1;
+  }
+
+  /** Returns whether the upload has reached a completed state. */
+  public boolean isCompleted() {
+    return getState() == State.FINALIZED;
+  }
+
+  /**
+   * Returns the upload progress as a fraction between 0.0 and 1.0, or -1.0 if total size is
+   * unknown.
+   *
+   * @return progress fraction between 0.0 and 1.0, or -1.0 if unknown
+   */
+  public double getProgressFraction() {
+    if (isIndeterminate()) {
+      return -1.0;
+    }
+    if (getTotalBytes() == 0) {
+      return 1.0;
+    }
+    return (double) getBytesUploaded() / getTotalBytes();
+  }
+
+  public abstract Builder toBuilder();
+
+  public static Builder builder() {
+    return new AutoValue_ResumableUploadStatus.Builder()
+        .setBytesUploaded(0L)
+        .setTotalBytes(-1L)
+        .setState(State.STARTED);
+  }
+
+  /**
+   * Creates a {@link ResumableUploadStatus} snapshot.
+   *
+   * @param uploadUrl the upload session URI
+   * @param bytesUploaded the number of bytes uploaded so far
+   * @param totalBytes the total size of the payload in bytes, or -1 if unknown
+   * @param state the current upload state
+   * @return a new {@link ResumableUploadStatus} instance
+   */
+  public static ResumableUploadStatus create(
+      String uploadUrl, long bytesUploaded, long totalBytes, State state) {
+    return builder()
+        .setUploadUrl(uploadUrl)
+        .setBytesUploaded(bytesUploaded)
+        .setTotalBytes(totalBytes)
+        .setState(state)
+        .build();
+  }
+
+  @AutoValue.Builder
+  public abstract static class Builder {
+    public abstract Builder setUploadUrl(String uploadUrl);
+
+    public abstract Builder setBytesUploaded(long bytesUploaded);
+
+    public abstract Builder setTotalBytes(long totalBytes);
+
+    public abstract Builder setState(State state);
+
+    abstract ResumableUploadStatus autoBuild();
+
+    public ResumableUploadStatus build() {
+      ResumableUploadStatus status = autoBuild();
+      Preconditions.checkArgument(
+          status.getBytesUploaded() >= 0, "bytesUploaded must be non-negative");
+      Preconditions.checkArgument(status.getTotalBytes() >= -1, "totalBytes must be >= -1");
+      if (status.getTotalBytes() >= 0) {
+        Preconditions.checkArgument(
+            status.getBytesUploaded() <= status.getTotalBytes(),
+            "bytesUploaded must be <= totalBytes");
+      }
+      return status;
+    }
+  }
+}
diff --git a/sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/resumableupload/ResumableUploadStatusTest.java b/sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/resumableupload/ResumableUploadStatusTest.java
new file mode 100644
index 000000000000..3765215f805d
--- /dev/null
+++ b/sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/resumableupload/ResumableUploadStatusTest.java
@@ -0,0 +1,150 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.resumableupload;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.concurrent.atomic.AtomicReference;
+import org.junit.jupiter.api.Test;
+
+class ResumableUploadStatusTest {
+
+  private static final String UPLOAD_URL = "https://storage.googleapis.com/upload/session/12345";
+
+  @Test
+  void status_enforcesBoundsAndInvariants() {
+    // Valid status: bytesUploaded >= 0, totalBytes == -1 (indeterminate)
+    ResumableUploadStatus streamingStatus =
+        ResumableUploadStatus.create(
+            UPLOAD_URL, 500L, -1L, ResumableUploadStatus.State.UPLOADING);
+    assertThat(streamingStatus.getBytesUploaded()).isEqualTo(500L);
+    assertThat(streamingStatus.getTotalBytes()).isEqualTo(-1L);
+    assertThat(streamingStatus.isIndeterminate()).isTrue();
+    assertThat(streamingStatus.isCompleted()).isFalse();
+
+    // Valid status: known totalBytes with bytesUploaded <= totalBytes
+    ResumableUploadStatus knownStatus =
+        ResumableUploadStatus.create(
+            UPLOAD_URL, 1000L, 2000L, ResumableUploadStatus.State.UPLOADING);
+    assertThat(knownStatus.getBytesUploaded()).isEqualTo(1000L);
+    assertThat(knownStatus.getTotalBytes()).isEqualTo(2000L);
+    assertThat(knownStatus.isIndeterminate()).isFalse();
+    assertThat(knownStatus.isCompleted()).isFalse();
+
+    // Invalid: negative bytesUploaded
+    assertThrows(
+        IllegalArgumentException.class,
+        () ->
+            ResumableUploadStatus.create(
+                UPLOAD_URL, -1L, 1000L, ResumableUploadStatus.State.UPLOADING));
+
+    // Invalid: totalBytes < -1
+    assertThrows(
+        IllegalArgumentException.class,
+        () ->
+            ResumableUploadStatus.create(
+                UPLOAD_URL, 0L, -2L, ResumableUploadStatus.State.STARTED));
+
+    // Invalid: bytesUploaded > totalBytes when totalBytes >= 0
+    assertThrows(
+        IllegalArgumentException.class,
+        () ->
+            ResumableUploadStatus.create(
+                UPLOAD_URL, 2001L, 2000L, ResumableUploadStatus.State.UPLOADING));
+  }
+
+  @Test
+  void status_calculatesProgressFractionCorrectly() {
+    // Indeterminate stream (-1)
+    ResumableUploadStatus indeterminate =
+        ResumableUploadStatus.create(
+            UPLOAD_URL, 512L, -1L, ResumableUploadStatus.State.UPLOADING);
+    assertThat(indeterminate.getProgressFraction()).isEqualTo(-1.0);
+
+    // 0-byte upload
+    ResumableUploadStatus zeroByte =
+        ResumableUploadStatus.create(
+            UPLOAD_URL, 0L, 0L, ResumableUploadStatus.State.FINALIZED);
+    assertThat(zeroByte.getProgressFraction()).isEqualTo(1.0);
+    assertThat(zeroByte.isCompleted()).isTrue();
+
+    // Halfway uploaded
+    ResumableUploadStatus halfway =
+        ResumableUploadStatus.create(
+            UPLOAD_URL, 500L, 1000L, ResumableUploadStatus.State.UPLOADING);
+    assertThat(halfway.getProgressFraction()).isEqualTo(0.5);
+
+    // Completed upload
+    ResumableUploadStatus completed =
+        ResumableUploadStatus.create(
+            UPLOAD_URL, 1000L, 1000L, ResumableUploadStatus.State.FINALIZED);
+    assertThat(completed.getProgressFraction()).isEqualTo(1.0);
+    assertThat(completed.isCompleted()).isTrue();
+  }
+
+  @Test
+  void status_builderAndToBuilderSupport() {
+    ResumableUploadStatus initial =
+        ResumableUploadStatus.builder()
+            .setUploadUrl(UPLOAD_URL)
+            .setBytesUploaded(0L)
+            .setTotalBytes(5000L)
+            .setState(ResumableUploadStatus.State.STARTED)
+            .build();
+
+    assertThat(initial.getState()).isEqualTo(ResumableUploadStatus.State.STARTED);
+    assertThat(initial.getBytesUploaded()).isEqualTo(0L);
+
+    ResumableUploadStatus updated =
+        initial.toBuilder()
+            .setBytesUploaded(2500L)
+            .setState(ResumableUploadStatus.State.UPLOADING)
+            .build();
+
+    assertThat(updated.getBytesUploaded()).isEqualTo(2500L);
+    assertThat(updated.getState()).isEqualTo(ResumableUploadStatus.State.UPLOADING);
+    assertThat(updated.getProgressFraction()).isEqualTo(0.5);
+  }
+
+  @Test
+  void progressListener_dispatchesStatusSnapshot() {
+    AtomicReference<ResumableUploadStatus> capturedStatus = new AtomicReference<>();
+    ResumableUploadProgressListener listener = capturedStatus::set;
+
+    ResumableUploadStatus status =
+        ResumableUploadStatus.create(
+            UPLOAD_URL, 1024L, 2048L, ResumableUploadStatus.State.UPLOADING);
+    listener.onProgress(status);
+
+    assertThat(capturedStatus.get()).isEqualTo(status);
+    assertThat(capturedStatus.get().getProgressFraction()).isEqualTo(0.5);
+  }
+}