diff --git a/src/test/java/edu/harvard/iq/dataverse/api/S3AccessDirectIT.java b/src/test/java/edu/harvard/iq/dataverse/api/S3AccessDirectIT.java
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+++ b/src/test/java/edu/harvard/iq/dataverse/api/S3AccessDirectIT.java
@@ -0,0 +1,97 @@
+package edu.harvard.iq.dataverse.api;
+
+import io.restassured.RestAssured;
+import static io.restassured.RestAssured.given;
+import io.restassured.path.json.JsonPath;
+import io.restassured.response.Response;
+import io.restassured.specification.RequestSpecification;
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.io.UnsupportedEncodingException;
+import java.net.URLDecoder;
+import java.nio.charset.StandardCharsets;
+import org.apache.commons.lang3.math.NumberUtils;
+import org.junit.jupiter.api.Test;
+
+public class S3AccessDirectIT {
+
+    @Test
+    public void testS3DirectUpload() {
+        // TODO: remove all these constants
+        RestAssured.baseURI = "https://demo.dataverse.org";
+        String apiToken = "";
+        String datasetPid = "doi:10.70122/FK2/UBWSJU";
+        String datasetId = "2106131";
+        long size = 1000000000l;
+
+        Response getUploadUrls = getUploadUrls(datasetPid, size, apiToken);
+        getUploadUrls.prettyPrint();
+        getUploadUrls.then().assertThat().statusCode(200);
+
+        String url = JsonPath.from(getUploadUrls.asString()).getString("data.url");
+        String partSize = JsonPath.from(getUploadUrls.asString()).getString("data.partSize");
+        String storageIdentifier = JsonPath.from(getUploadUrls.asString()).getString("data.storageIdentifier");
+        System.out.println("url: " + url);
+        System.out.println("partSize: " + partSize);
+        System.out.println("storageIdentifier: " + storageIdentifier);
+
+        System.out.println("uploading file via direct upload");
+        String decodedUrl = null;
+        try {
+            decodedUrl = URLDecoder.decode(url, StandardCharsets.UTF_8.name());
+        } catch (UnsupportedEncodingException ex) {
+        }
+
+        InputStream inputStream = new ByteArrayInputStream("bumble".getBytes(StandardCharsets.UTF_8));
+        Response uploadFileDirect = uploadFileDirect(decodedUrl, inputStream);
+        uploadFileDirect.prettyPrint();
+        uploadFileDirect.then().assertThat().statusCode(200);
+
+        // TODO: Use MD5 or whatever Dataverse is configured for and
+        // actually calculate it.
+        String jsonData = """
+{
+    "description": "My description.",
+    "directoryLabel": "data/subdir1",
+    "categories": [
+      "Data"
+    ],
+    "restrict": "false",
+    "storageIdentifier": "%s",
+    "fileName": "file1.txt",
+    "mimeType": "text/plain",
+    "checksum": {
+      "@type": "SHA-1",
+      "@value": "123456"
+    }
+}
+""".formatted(storageIdentifier);
+        Response addRemoteFile = UtilIT.addRemoteFile(datasetId, jsonData, apiToken);
+        addRemoteFile.prettyPrint();
+        addRemoteFile.then().assertThat()
+                .statusCode(200);
+    }
+
+    static Response getUploadUrls(String idOrPersistentIdOfDataset, long sizeInBytes, String apiToken) {
+        String idInPath = idOrPersistentIdOfDataset; // Assume it's a number.
+        String optionalQueryParam = ""; // If idOrPersistentId is a number we'll just put it in the path.
+        if (!NumberUtils.isCreatable(idOrPersistentIdOfDataset)) {
+            idInPath = ":persistentId";
+            optionalQueryParam = "&persistentId=" + idOrPersistentIdOfDataset;
+        }
+        RequestSpecification requestSpecification = given();
+        if (apiToken != null) {
+            requestSpecification = given()
+                    .header(UtilIT.API_TOKEN_HTTP_HEADER, apiToken);
+        }
+        return requestSpecification.get("/api/datasets/" + idInPath + "/uploadurls?size=" + sizeInBytes + optionalQueryParam);
+    }
+
+    static Response uploadFileDirect(String url, InputStream inputStream) {
+        return given()
+                .header("x-amz-tagging", "dv-state=temp")
+                .body(inputStream)
+                .put(url);
+    }
+
+}