diff --git a/packages/nbdime/src/diff/model/cell.ts b/packages/nbdime/src/diff/model/cell.ts
index 4dbed206..9ce136d7 100644
--- a/packages/nbdime/src/diff/model/cell.ts
+++ b/packages/nbdime/src/diff/model/cell.ts
@@ -43,12 +43,14 @@ export class CellDiffModel {
               metadata: IStringDiffModel,
               outputs: OutputDiffModel[] | null,
               executionCount: ImmutableDiffModel | null,
-              cellType: string) {
+              cellType: string,
+              cellId: ImmutableDiffModel) {
     this.source = source;
     this.metadata = metadata;
     this.outputs = outputs;
     this.executionCount = executionCount;
     this.cellType = cellType;
+    this.cellId = cellId;
     if (outputs === null && cellType === 'code') {
       throw new NotifyUserError('Invalid code cell, missing outputs!');
     }
@@ -88,6 +90,10 @@ export class CellDiffModel {
    */
   cellType: string;
 
+  /**
+   * Diff model for the cell identifier.
+   */
+  cellId: ImmutableDiffModel;
 
   /**
    * Whether the cell has remained unchanged
@@ -195,7 +201,10 @@ function createPatchedCellDiffModel(
     // Pass base as remote, which means fall back to unchanged if no diff:
     executionCount = createImmutableModel(execBase, execBase, execDiff);
   }
-  return new CellDiffModel(source, metadata, outputs, executionCount, base.cell_type);
+  let idBase = base.id as string | undefined;
+  let idDiff = getDiffEntryByKey(diff, 'id') as IDiffReplace | null;
+  const idModel = createImmutableModel(idBase, idBase, idDiff);
+  return new CellDiffModel(source, metadata, outputs, executionCount, base.cell_type, idModel);
 }
 
 export
@@ -215,7 +224,9 @@ function createUnchangedCellDiffModel(
   } else {  // markdown or raw cell
 
   }
-  return new CellDiffModel(source, metadata, outputs, executionCount, base.cell_type);
+  let idBase = base.id as string | undefined;
+  const idModel = createImmutableModel(idBase, idBase);
+  return new CellDiffModel(source, metadata, outputs, executionCount, base.cell_type, idModel);
 }
 
 export
@@ -231,7 +242,9 @@ function createAddedCellDiffModel(
       null, remote.outputs);
     executionCount = createImmutableModel(null, remote.execution_count);
   }
-  return new CellDiffModel(source, metadata, outputs, executionCount, remote.cell_type);
+  let idRemote = remote.id as string | undefined;
+  const idModel = createImmutableModel(null, idRemote);
+  return new CellDiffModel(source, metadata, outputs, executionCount, remote.cell_type, idModel);
 }
 
 export
@@ -247,5 +260,7 @@ function createDeletedCellDiffModel(
     let execBase = base.execution_count;
     executionCount = createImmutableModel(execBase, null);
   }
-  return new CellDiffModel(source, metadata, outputs, executionCount, base.cell_type);
+  let idBase = base.id as string | undefined;
+  const idModel = createImmutableModel(idBase, null);
+  return new CellDiffModel(source, metadata, outputs, executionCount, base.cell_type, idModel);
 }
diff --git a/packages/nbdime/src/diff/model/immutable.ts b/packages/nbdime/src/diff/model/immutable.ts
index d4db808d..9b712221 100644
--- a/packages/nbdime/src/diff/model/immutable.ts
+++ b/packages/nbdime/src/diff/model/immutable.ts
@@ -12,7 +12,7 @@ import type {
 
 
 
-export type ImmutableValue = number | boolean | null;
+export type ImmutableValue = string | number | boolean | null;
 
 
 /**
diff --git a/packages/nbdime/src/diff/widget/cell.ts b/packages/nbdime/src/diff/widget/cell.ts
index 12a7c0c9..62b4eb35 100644
--- a/packages/nbdime/src/diff/widget/cell.ts
+++ b/packages/nbdime/src/diff/widget/cell.ts
@@ -53,7 +53,9 @@ const CELLDIFF_CLASS = 'jp-Cell-diff';
 export
 const OUTPUTS_DIFF_CLASS = 'jp-Diff-outputsContainer';
 
-const EXECUTIONCOUNT_ROW_CLASS = 'jp-Cellrow-executionCount';
+const EXECUTION_COUNT_CLASS = 'jp-Cellrow-header-executionCount';
+const CELL_ID_CLASS = 'jp-Cellrow-header-cellId';
+const HEADER_ROW_CLASS = 'jp-Cellrow-header';
 const SOURCE_ROW_CLASS = 'jp-Cellrow-source';
 const METADATA_ROW_CLASS = 'jp-Cellrow-metadata';
 const OUTPUTS_ROW_CLASS = 'jp-Cellrow-outputs';
@@ -100,10 +102,41 @@ class CellDiffWidget extends Panel {
     let sourceView = CellDiffWidget.createView(
       model.source, model, CURR_DIFF_CLASSES, this._rendermime);
     sourceView.addClass(SOURCE_ROW_CLASS);
-    if (model.executionCount) {
-      sourceView.insertWidget(0, CellDiffWidget.createPrompts(
-        model.executionCount, model));
+
+    if (model.executionCount || model.cellId) {
+      const createWidget = (text: string): Widget => {
+        let w = new Widget();
+        w.node.innerText = text;
+        return w;
+      }
+      const header = CellDiffWidget.createHeader();
+      FlexPanel.setGrow(header, 1);
+      sourceView.insertWidget(0, header);
+
+      const prompts = model.executionCount ? CellDiffWidget.createPrompts(
+          model.executionCount, model) : {base: null, remote: null}
+      const ids = model.cellId ? CellDiffWidget.createIdentifiers(
+          model.cellId, model) : {base: null, remote: null}
+
+      const views: ('base' | 'remote')[] = ['base', 'remote'];
+      for (let side of views) {
+        const prompt = prompts[side];
+        const id = ids[side];
+        if (model.executionCount && prompt !== null) {
+          let w = createWidget(prompt);
+          w.addClass(PROMPT_CLASS);
+          w.addClass(EXECUTION_COUNT_CLASS);
+          header.addWidget(w);
+        }
+        if (model.cellId && id !== null) {
+          let w = createWidget(`Cell ID: ${id}`);
+          w.addClass(CELL_ID_CLASS);
+          FlexPanel.setGrow(w, 1);
+          header.addWidget(w);
+        }
+      }
     }
+
     this.addWidget(sourceView);
 
     if (!model.metadata.unchanged) {
@@ -157,28 +190,33 @@ class CellDiffWidget extends Panel {
     }
   }
 
-  static createPrompts(model: ImmutableDiffModel, parent: CellDiffModel): Panel {
-    let prompts: string[] = [];
+  static createHeader(): Panel {
+    let container = new FlexPanel({direction: 'left-to-right'});
+    container.addClass(HEADER_ROW_CLASS);
+    return container;
+  }
+
+  static createPrompts(model: ImmutableDiffModel, parent: CellDiffModel): Record<'base' | 'remote', string | null> {
+    const prompts: Record<'base' | 'remote', string | null> = {
+      base: null,
+      remote: null
+    }
     if (!parent.added) {
       let base = model.base as number | null;
-      let baseStr = `In [${base || ' '}]:`;
-      prompts.push(baseStr);
+      prompts.base = `In [${base || ' '}]:`;
     }
     if (!parent.unchanged && !parent.deleted) {
       let remote = model.remote as number | null;
-      let remoteStr = `In [${remote || ' '}]:`;
-      prompts.push(remoteStr);
+      prompts.remote = `In [${remote || ' '}]:`;
     }
-    let container = new FlexPanel({direction: 'left-to-right'});
-    for (let text of prompts) {
-      let w = new Widget();
-      w.node.innerText = text;
-      w.addClass(PROMPT_CLASS);
-      container.addWidget(w);
-      FlexPanel.setGrow(w, 1);
-    }
-    container.addClass(EXECUTIONCOUNT_ROW_CLASS);
-    return container;
+    return prompts;
+  }
+
+  static createIdentifiers(model: ImmutableDiffModel, parent: CellDiffModel): Record<'base' | 'remote', string | null> {
+    return {
+      base: model.base as string | null,
+      remote: model.remote as string | null
+    };
   }
 
   /**
diff --git a/packages/nbdime/src/merge/model/cell.ts b/packages/nbdime/src/merge/model/cell.ts
index 5f83b6d7..f34a220a 100644
--- a/packages/nbdime/src/merge/model/cell.ts
+++ b/packages/nbdime/src/merge/model/cell.ts
@@ -115,7 +115,8 @@ function createPatchedCellDecisionDiffModel(
 
   }
 
-  return new CellDiffModel(source, metadata, outputs, executionCount, base.cell_type);
+  let idModel = createImmutableModel(base.id ? (base.id as string) : null, null);
+  return new CellDiffModel(source, metadata, outputs, executionCount, base.cell_type, idModel);
 }
 
 
diff --git a/packages/nbdime/src/styles/diff.css b/packages/nbdime/src/styles/diff.css
index 4b31500f..672797d9 100644
--- a/packages/nbdime/src/styles/diff.css
+++ b/packages/nbdime/src/styles/diff.css
@@ -29,11 +29,20 @@
     border: none;
 }
 
-/* We can float prompt left when unchanged */
-.jp-Notebook-diff .jp-Diff-unchanged .jp-Cellrow-executionCount {
+/* When unchanged hide cell ids and float the execution count left */
+.jp-Notebook-diff .jp-Diff-unchanged .jp-Cellrow-header-cellId {
+  display: none;
+}
+
+.jp-Notebook-diff .jp-Diff-unchanged .jp-Cellrow-header {
   float: left;
 }
 
+.jp-Notebook-diff .jp-Cellrow-header-cellId {
+  align-self: center;
+  text-align: center;
+  color: var(--jp-ui-font-color2);
+}
 
 .jp-Notebook-diff .jp-Metadata-diff {
   margin-bottom: 20px;
@@ -178,8 +187,9 @@
   width: 100%;
 }
 
-.jp-Notebook-diff .jp-Cellrow-source .jp-InputPrompt {
+.jp-Notebook-diff .jp-Cellrow-header > .jp-InputPrompt {
   text-align: left;
+  flex-basis: min-content;
 }
 
 .jp-CollapsiblePanel-container {