diff --git a/packages/blockly/src/manager.ts b/packages/blockly/src/manager.ts
index b29a432..f97bc69 100644
--- a/packages/blockly/src/manager.ts
+++ b/packages/blockly/src/manager.ts
@@ -8,7 +8,14 @@ import { ISignal, Signal } from '@lumino/signaling';
 import * as Blockly from 'blockly';
 
 import { BlocklyRegistry } from './registry';
-import { ToolboxDefinition } from 'blockly/core/utils/toolbox';
+import {
+  BlockInfo,
+  DynamicCategoryInfo,
+  StaticCategoryInfo,
+  ToolboxDefinition,
+  ToolboxInfo,
+  ToolboxItemInfo
+} from 'blockly/core/utils/toolbox';
 
 /**
  * BlocklyManager the manager for each document
@@ -17,6 +24,7 @@ import { ToolboxDefinition } from 'blockly/core/utils/toolbox';
  */
 export class BlocklyManager {
   private _toolbox: string;
+  private _allowedBlocks: string[];
   private _generator: Blockly.Generator;
   private _registry: BlocklyRegistry;
   private _selectedKernel: KernelSpec.ISpecModel;
@@ -37,6 +45,7 @@ export class BlocklyManager {
     this._mimetypeService = mimetypeService;
 
     this._toolbox = 'default';
+    this._filterToolbox();
     this._generator = this._registry.generators.get('python');
 
     this._changed = new Signal<this, BlocklyManager.Change>(this);
@@ -112,6 +121,7 @@ export class BlocklyManager {
     if (this._toolbox !== name) {
       const toolbox = this._registry.toolboxes.get(name);
       this._toolbox = toolbox ? name : 'default';
+      this._filterToolbox();
       this._changed.emit('toolbox');
     }
   }
@@ -129,6 +139,79 @@ export class BlocklyManager {
     return list;
   }
 
+  /**
+   * Get the list of allowed blocks. If undefined, all blocks are allowed.
+   *
+   * @returns The list of allowed blocks.
+   */
+  getAllowedBlocks() {
+    return this._allowedBlocks;
+  }
+
+  /**
+   * Set the list of allowed blocks. If undefined, all blocks are allowed.
+   *
+   * @param allowedBlocks The list of allowed blocks.
+   */
+  setAllowedBlocks(allowedBlocks: string[]) {
+    this._allowedBlocks = allowedBlocks;
+    this._filterToolbox();
+    this._changed.emit('toolbox');
+  }
+
+  private _filterToolbox() {
+    const toolbox = this._registry.toolboxes.get(this._toolbox) as ToolboxInfo;
+    if (toolbox) {
+      this._filterContents(toolbox.contents);
+    }
+  }
+
+  private _filterContents(contents: ToolboxItemInfo[]): number {
+    let visible = 0;
+    contents.forEach(itemInfo => {
+      if ('kind' in itemInfo) {
+        if (itemInfo.kind.toUpperCase() === 'CATEGORY') {
+          if ('contents' in itemInfo) {
+            const categoryInfo = itemInfo as StaticCategoryInfo;
+            if (this._filterContents(categoryInfo.contents) > 0) {
+              visible++;
+              categoryInfo.hidden = 'false';
+            } else {
+              categoryInfo.hidden = 'true';
+            }
+          } else if ('custom' in itemInfo) {
+            const categoryInfo = itemInfo as DynamicCategoryInfo;
+            if (
+              this._allowedBlocks === undefined ||
+              this._allowedBlocks.includes(categoryInfo.custom.toLowerCase())
+            ) {
+              categoryInfo.hidden = 'false';
+              visible++;
+              console.log(`Category ${categoryInfo.custom} is allowed`);
+            } else {
+              categoryInfo.hidden = 'true';
+              console.log(`Category ${categoryInfo.custom} is not allowed`);
+            }
+          }
+        } else if (itemInfo.kind.toUpperCase() === 'BLOCK') {
+          const blockInfo = itemInfo as BlockInfo;
+          if (
+            this._allowedBlocks === undefined ||
+            this._allowedBlocks.includes(blockInfo.type.toLowerCase())
+          ) {
+            blockInfo.disabled = false;
+            blockInfo.disabledReasons = [];
+            visible++;
+          } else {
+            blockInfo.disabled = true;
+            blockInfo.disabledReasons = ['This block is not allowed'];
+          }
+        }
+      }
+    });
+    return visible;
+  }
+
   /**
    * Set the selected kernel.
    *
diff --git a/packages/blockly/src/widget.ts b/packages/blockly/src/widget.ts
index b648951..fa3f605 100644
--- a/packages/blockly/src/widget.ts
+++ b/packages/blockly/src/widget.ts
@@ -5,7 +5,9 @@ import {
 } from '@jupyterlab/docregistry';
 import { IRenderMimeRegistry } from '@jupyterlab/rendermime';
 import { runIcon } from '@jupyterlab/ui-components';
+import { showErrorMessage } from '@jupyterlab/apputils';
 
+import { PartialJSONObject } from '@lumino/coreutils';
 import { SplitPanel } from '@lumino/widgets';
 import { Signal } from '@lumino/signaling';
 
@@ -82,6 +84,7 @@ export namespace BlocklyEditor {
  */
 export class BlocklyPanel extends SplitPanel {
   private _context: DocumentRegistry.IContext<DocumentModel>;
+  private _manager: BlocklyManager;
   private _rendermime: IRenderMimeRegistry;
 
   /**
@@ -105,6 +108,7 @@ export class BlocklyPanel extends SplitPanel {
     });
     this.addClass('jp-BlocklyPanel');
     this._context = context;
+    this._manager = manager;
     this._rendermime = rendermime;
 
     // Load the content of the file when the context is ready
@@ -139,9 +143,55 @@ export class BlocklyPanel extends SplitPanel {
   }
 
   private _load(): void {
-    // Loading the content of the document into the workspace
-    const content = this._context.model.toJSON() as any as Blockly.Workspace;
-    (this.layout as BlocklyLayout).workspace = content;
+    const fileContent = this._context.model.toJSON();
+    const fileFormat = fileContent['format'];
+    // Check if format is set or if we have legacy content
+    if (fileFormat === undefined && fileContent['blocks']) {
+      // Load legacy content
+      (this.layout as BlocklyLayout).workspace =
+        fileContent as any as Blockly.Workspace;
+    } else if (fileFormat === 2) {
+      // Load the content from the "workspace" key
+      const workspace = fileContent['workspace'] as any as Blockly.Workspace;
+      (this.layout as BlocklyLayout).workspace = workspace;
+      const metadata = fileContent['metadata'];
+      if (metadata) {
+        if (metadata['toolbox']) {
+          const toolbox = metadata['toolbox'];
+          if (
+            this._manager.listToolboxes().find(value => value.value === toolbox)
+          ) {
+            this._manager.setToolbox(metadata['toolbox']);
+          } else {
+            // Unknown toolbox
+            showErrorMessage(
+              'Unknown toolbox',
+              `The toolbox '${toolbox}' is not available. Using default toolbox.`
+            );
+          }
+        }
+        if (metadata['kernel'] && metadata['kernel'] !== 'No kernel') {
+          const kernel = metadata['kernel'];
+          if (
+            this._manager.listKernels().find(value => value.value === kernel)
+          ) {
+            this._manager.selectKernel(metadata['kernel']);
+          } else {
+            // Unknown kernel
+            console.warn(`Unknown kernel in blockly file: ${kernel}`);
+          }
+        }
+        if (metadata['allowed_blocks']) {
+          this._manager.setAllowedBlocks(metadata['allowed_blocks']);
+        }
+      }
+    } else {
+      // Unsupported format
+      showErrorMessage(
+        'Unsupported file format',
+        `The file format '${fileFormat}' is not supported by the Blockly editor.`
+      );
+    }
   }
 
   private _onSave(
@@ -150,7 +200,16 @@ export class BlocklyPanel extends SplitPanel {
   ): void {
     if (state === 'started') {
       const workspace = (this.layout as BlocklyLayout).workspace;
-      this._context.model.fromJSON(workspace as any);
+      const fileContent: PartialJSONObject = {
+        format: 2,
+        workspace: workspace as any,
+        metadata: {
+          toolbox: this._manager.getToolbox(),
+          allowed_blocks: this._manager.getAllowedBlocks(),
+          kernel: this._manager.kernel
+        }
+      };
+      this._context.model.fromJSON(fileContent);
     }
   }
 }