diff --git a/webapp/public/locales/en/main.json b/webapp/public/locales/en/main.json
index fbf36b7380..311c5f72a6 100644
--- a/webapp/public/locales/en/main.json
+++ b/webapp/public/locales/en/main.json
@@ -240,6 +240,7 @@
   "study.bindingconstraints": "Binding Constraints",
   "study.debug": "Debug",
   "study.debug.file.image": "Image file",
+  "study.debug.folder.empty": "Folder is empty",
   "study.failtofetchlogs": "Failed to fetch logs",
   "study.failtokilltask": "Failed to kill task",
   "study.publicMode": "Public mode",
diff --git a/webapp/public/locales/fr/main.json b/webapp/public/locales/fr/main.json
index 46b90928e5..fca4ba978c 100644
--- a/webapp/public/locales/fr/main.json
+++ b/webapp/public/locales/fr/main.json
@@ -240,6 +240,7 @@
   "study.bindingconstraints": "Contraintes Couplantes",
   "study.debug": "Debug",
   "study.debug.file.image": "Fichier image",
+  "study.debug.folder.empty": "Le dossier est vide",
   "study.failtofetchlogs": "Échec du chargement des logs",
   "study.failtokilltask": "Échec de l'annulation de l'étude",
   "study.publicMode": "Mode public",
diff --git a/webapp/src/components/App/Singlestudy/explore/Debug/Data/Folder.tsx b/webapp/src/components/App/Singlestudy/explore/Debug/Data/Folder.tsx
new file mode 100644
index 0000000000..4d8490713f
--- /dev/null
+++ b/webapp/src/components/App/Singlestudy/explore/Debug/Data/Folder.tsx
@@ -0,0 +1,68 @@
+import {
+  Divider,
+  List,
+  ListItemButton,
+  ListItemIcon,
+  ListItemText,
+  ListSubheader,
+} from "@mui/material";
+import FolderIcon from "@mui/icons-material/Folder";
+import {
+  getFileIcon,
+  getFileType,
+  type TreeFolder,
+  type DataCompProps,
+} from "../utils";
+import ViewWrapper from "../../../../../common/page/ViewWrapper";
+import { Fragment } from "react";
+import EmptyView from "../../../../../common/page/SimpleContent";
+import { useTranslation } from "react-i18next";
+
+function Folder({
+  filename,
+  filePath,
+  treeData,
+  setSelectedFile,
+}: DataCompProps) {
+  const { t } = useTranslation();
+  const list = Object.entries(treeData as TreeFolder);
+
+  return (
+    <ViewWrapper>
+      <List subheader={<ListSubheader>{filename}</ListSubheader>} dense>
+        {list.length > 0 ? (
+          list.map(([filename, data], index, arr) => {
+            const fileType = getFileType(data);
+            const Icon = getFileIcon(fileType);
+            const isLast = index === arr.length - 1;
+
+            return (
+              <Fragment key={filename}>
+                <ListItemButton
+                  onClick={() =>
+                    setSelectedFile({
+                      fileType,
+                      filename,
+                      filePath: `${filePath}/${filename}`,
+                      treeData: data,
+                    })
+                  }
+                >
+                  <ListItemIcon>
+                    <Icon />
+                  </ListItemIcon>
+                  <ListItemText primary={filename} />
+                </ListItemButton>
+                {!isLast && <Divider variant="fullWidth" />}
+              </Fragment>
+            );
+          })
+        ) : (
+          <EmptyView title={t("study.debug.folder.empty")} icon={FolderIcon} />
+        )}
+      </List>
+    </ViewWrapper>
+  );
+}
+
+export default Folder;
diff --git a/webapp/src/components/App/Singlestudy/explore/Debug/Data/Matrix.tsx b/webapp/src/components/App/Singlestudy/explore/Debug/Data/Matrix.tsx
index 7b48f04bc6..efcdd7089d 100644
--- a/webapp/src/components/App/Singlestudy/explore/Debug/Data/Matrix.tsx
+++ b/webapp/src/components/App/Singlestudy/explore/Debug/Data/Matrix.tsx
@@ -3,9 +3,7 @@ import MatrixInput from "../../../../../common/MatrixInput";
 import ViewWrapper from "../../../../../common/page/ViewWrapper";
 import type { DataCompProps } from "../utils";
 
-function Matrix({ studyId, filePath, enableImport }: DataCompProps) {
-  const filename = filePath.split("/").pop();
-
+function Matrix({ studyId, filename, filePath, enableImport }: DataCompProps) {
   return (
     <ViewWrapper>
       <MatrixInput
diff --git a/webapp/src/components/App/Singlestudy/explore/Debug/Data/index.tsx b/webapp/src/components/App/Singlestudy/explore/Debug/Data/index.tsx
index 813624dfbb..d81a74b549 100644
--- a/webapp/src/components/App/Singlestudy/explore/Debug/Data/index.tsx
+++ b/webapp/src/components/App/Singlestudy/explore/Debug/Data/index.tsx
@@ -2,11 +2,13 @@ import Text from "./Text";
 import Image from "./Image";
 import Json from "./Json";
 import Matrix from "./Matrix";
+import Folder from "./Folder";
 import type { FileInfo, FileType } from "../utils";
 import type { DataCompProps } from "../utils";
 
 interface Props extends FileInfo {
   studyId: string;
+  setSelectedFile: (file: FileInfo) => void;
 }
 
 type DataComponent = React.ComponentType<DataCompProps>;
@@ -16,18 +18,20 @@ const componentByFileType: Record<FileType, DataComponent> = {
   json: Json,
   text: Text,
   image: Image,
-  folder: ({ filePath }) => filePath,
+  folder: Folder,
 } as const;
 
-function Data({ studyId, fileType, filePath }: Props) {
+function Data({ studyId, setSelectedFile, ...fileInfo }: Props) {
+  const { fileType, filePath } = fileInfo;
   const isUserFolder = filePath.startsWith("/user/");
   const DataViewer = componentByFileType[fileType];
 
   return (
     <DataViewer
+      {...fileInfo}
       studyId={studyId}
-      filePath={filePath}
       enableImport={isUserFolder}
+      setSelectedFile={setSelectedFile}
     />
   );
 }
diff --git a/webapp/src/components/App/Singlestudy/explore/Debug/DebugContext.ts b/webapp/src/components/App/Singlestudy/explore/Debug/DebugContext.ts
index 436baa3560..a179a56980 100644
--- a/webapp/src/components/App/Singlestudy/explore/Debug/DebugContext.ts
+++ b/webapp/src/components/App/Singlestudy/explore/Debug/DebugContext.ts
@@ -3,7 +3,7 @@ import type { FileInfo } from "./utils";
 import { voidFn } from "../../../../../utils/fnUtils";
 
 const initialDebugContextValue = {
-  onFileSelect: voidFn<[FileInfo]>,
+  setSelectedFile: voidFn<[FileInfo]>,
   reloadTreeData: voidFn,
 };
 
diff --git a/webapp/src/components/App/Singlestudy/explore/Debug/Tree/FileTreeItem.tsx b/webapp/src/components/App/Singlestudy/explore/Debug/Tree/FileTreeItem.tsx
index 80a7da9443..0adc476129 100644
--- a/webapp/src/components/App/Singlestudy/explore/Debug/Tree/FileTreeItem.tsx
+++ b/webapp/src/components/App/Singlestudy/explore/Debug/Tree/FileTreeItem.tsx
@@ -6,14 +6,14 @@ import { useContext } from "react";
 
 interface Props {
   name: string;
-  content: TreeData;
   path: string;
+  treeData: TreeData;
 }
 
-function FileTreeItem({ name, content, path }: Props) {
-  const { onFileSelect } = useContext(DebugContext);
-  const filePath = `${path}/${name}`;
-  const fileType = getFileType(content);
+function FileTreeItem({ name, treeData, path }: Props) {
+  const { setSelectedFile } = useContext(DebugContext);
+  const filePath = path ? `${path}/${name}` : name;
+  const fileType = getFileType(treeData);
   const FileIcon = getFileIcon(fileType);
 
   ////////////////////////////////////////////////////////////////
@@ -21,9 +21,7 @@ function FileTreeItem({ name, content, path }: Props) {
   ////////////////////////////////////////////////////////////////
 
   const handleClick = () => {
-    if (fileType !== "folder") {
-      onFileSelect({ fileType, filePath });
-    }
+    setSelectedFile({ fileType, filename: name, filePath, treeData });
   };
 
   ////////////////////////////////////////////////////////////////
@@ -41,13 +39,13 @@ function FileTreeItem({ name, content, path }: Props) {
       }
       onClick={handleClick}
     >
-      {isFolder(content) &&
-        Object.keys(content).map((childName) => (
+      {isFolder(treeData) &&
+        Object.keys(treeData).map((childName) => (
           <FileTreeItem
             key={childName}
             name={childName}
-            content={content[childName]}
             path={filePath}
+            treeData={treeData[childName]}
           />
         ))}
     </TreeItem>
diff --git a/webapp/src/components/App/Singlestudy/explore/Debug/Tree/index.tsx b/webapp/src/components/App/Singlestudy/explore/Debug/Tree/index.tsx
index 917efdec83..c7ad5146cb 100644
--- a/webapp/src/components/App/Singlestudy/explore/Debug/Tree/index.tsx
+++ b/webapp/src/components/App/Singlestudy/explore/Debug/Tree/index.tsx
@@ -1,16 +1,60 @@
 import { SimpleTreeView } from "@mui/x-tree-view/SimpleTreeView";
 import FileTreeItem from "./FileTreeItem";
 import type { TreeFolder } from "../utils";
+import { useState } from "react";
 
 interface Props {
   data: TreeFolder;
+  // `selectedItems` must not be undefined to make `SimpleTreeView` controlled
+  selectedItemId: string | null;
 }
 
-function Tree({ data }: Props) {
+function getParentItemIds(itemId: string) {
+  // "a/b/c/d" -> ["a", "a/b", "a/b/c"]
+  return itemId
+    .split("/")
+    .slice(0, -1) // Remove the last item
+    .map((_, index, arr) => arr.slice(0, index + 1).join("/"));
+}
+
+function Tree({ data, selectedItemId }: Props) {
+  const [expandedItems, setExpandedItems] = useState<string[]>([]);
+
+  ////////////////////////////////////////////////////////////////
+  // Event Handlers
+  ////////////////////////////////////////////////////////////////
+
+  const handleExpandedItemsChange = (
+    event: React.SyntheticEvent,
+    itemIds: string[],
+  ) => {
+    setExpandedItems(itemIds);
+  };
+
+  ////////////////////////////////////////////////////////////////
+  // JSX
+  ////////////////////////////////////////////////////////////////
+
+  // `SimpleTreeView` must be controlled because selected item can be changed manually
+  // by `Folder` component
+
   return (
-    <SimpleTreeView>
-      {Object.keys(data).map((key) => (
-        <FileTreeItem key={key} name={key} content={data[key]} path="" />
+    <SimpleTreeView
+      selectedItems={selectedItemId}
+      expandedItems={
+        selectedItemId
+          ? [...expandedItems, ...getParentItemIds(selectedItemId)]
+          : expandedItems
+      }
+      onExpandedItemsChange={handleExpandedItemsChange}
+    >
+      {Object.keys(data).map((filename) => (
+        <FileTreeItem
+          key={filename}
+          name={filename}
+          treeData={data[filename]}
+          path=""
+        />
       ))}
     </SimpleTreeView>
   );
diff --git a/webapp/src/components/App/Singlestudy/explore/Debug/index.tsx b/webapp/src/components/App/Singlestudy/explore/Debug/index.tsx
index 97e20f34d3..864895b528 100644
--- a/webapp/src/components/App/Singlestudy/explore/Debug/index.tsx
+++ b/webapp/src/components/App/Singlestudy/explore/Debug/index.tsx
@@ -9,14 +9,20 @@ import UsePromiseCond from "../../../../common/utils/UsePromiseCond";
 import usePromiseWithSnackbarError from "../../../../../hooks/usePromiseWithSnackbarError";
 import { getStudyData } from "../../../../../services/api/study";
 import DebugContext from "./DebugContext";
-import type { FileInfo, TreeFolder } from "./utils";
+import {
+  getFileType,
+  type TreeData,
+  type FileInfo,
+  type TreeFolder,
+} from "./utils";
 import * as R from "ramda";
 import SplitView from "../../../../common/SplitView";
+import { useUpdateEffect } from "react-use";
 
 function Debug() {
   const [t] = useTranslation();
   const { study } = useOutletContext<{ study: StudyMetadata }>();
-  const [selectedFile, setSelectedFile] = useState<FileInfo>();
+  const [selectedFile, setSelectedFile] = useState<FileInfo | null>(null);
 
   const res = usePromiseWithSnackbarError(
     async () => {
@@ -31,12 +37,30 @@ function Debug() {
 
   const contextValue = useMemo(
     () => ({
-      onFileSelect: setSelectedFile,
+      setSelectedFile,
       reloadTreeData: res.reload,
     }),
     [res.reload],
   );
 
+  useUpdateEffect(() => {
+    const firstChildName = Object.keys(res.data ?? {})[0];
+    const treeData = R.path<TreeData>([firstChildName], res.data);
+
+    if (treeData) {
+      const fileInfo = {
+        fileType: getFileType(treeData),
+        filename: firstChildName,
+        filePath: firstChildName,
+        treeData,
+      };
+
+      setSelectedFile(fileInfo);
+    } else {
+      setSelectedFile(null);
+    }
+  }, [res?.data]);
+
   ////////////////////////////////////////////////////////////////
   // JSX
   ////////////////////////////////////////////////////////////////
@@ -48,12 +72,23 @@ function Debug() {
           response={res}
           ifResolved={(data) => (
             <DebugContext.Provider value={contextValue}>
-              <Tree data={data} />
+              <Tree
+                data={data}
+                selectedItemId={selectedFile?.filePath || null}
+              />
             </DebugContext.Provider>
           )}
         />
       </Box>
-      <Box>{selectedFile && <Data {...selectedFile} studyId={study.id} />}</Box>
+      <Box>
+        {selectedFile && (
+          <Data
+            {...selectedFile}
+            setSelectedFile={setSelectedFile}
+            studyId={study.id}
+          />
+        )}
+      </Box>
     </SplitView>
   );
 }
diff --git a/webapp/src/components/App/Singlestudy/explore/Debug/utils.ts b/webapp/src/components/App/Singlestudy/explore/Debug/utils.ts
index cda06034a3..50d3ae73cf 100644
--- a/webapp/src/components/App/Singlestudy/explore/Debug/utils.ts
+++ b/webapp/src/components/App/Singlestudy/explore/Debug/utils.ts
@@ -10,13 +10,6 @@ import * as RA from "ramda-adjunct";
 // Types
 ////////////////////////////////////////////////////////////////
 
-export type FileType = "json" | "matrix" | "text" | "image" | "folder";
-
-export interface FileInfo {
-  fileType: FileType;
-  filePath: string;
-}
-
 export type TreeFile = string | string[];
 
 export interface TreeFolder {
@@ -25,10 +18,19 @@ export interface TreeFolder {
 
 export type TreeData = TreeFolder | TreeFile;
 
-export interface DataCompProps {
-  studyId: string;
+export type FileType = "json" | "matrix" | "text" | "image" | "folder";
+
+export interface FileInfo {
+  fileType: FileType;
+  filename: string;
   filePath: string;
+  treeData: TreeData;
+}
+
+export interface DataCompProps extends FileInfo {
+  studyId: string;
   enableImport: boolean;
+  setSelectedFile: (file: FileInfo) => void;
 }
 
 ////////////////////////////////////////////////////////////////
diff --git a/webapp/src/theme.ts b/webapp/src/theme.ts
index efbe96392a..2ef92d99df 100644
--- a/webapp/src/theme.ts
+++ b/webapp/src/theme.ts
@@ -75,6 +75,13 @@ const theme = createTheme({
         },
       },
     },
+    MuiListSubheader: {
+      styleOverrides: {
+        root: {
+          backgroundColor: "#222333",
+        },
+      },
+    },
     MuiAlert: {
       styleOverrides: {
         root: {