diff --git a/packages/playwright-core/src/server/har/harTracer.ts b/packages/playwright-core/src/server/har/harTracer.ts
index 268da9e84d..cb423a144d 100644
--- a/packages/playwright-core/src/server/har/harTracer.ts
+++ b/packages/playwright-core/src/server/har/harTracer.ts
@@ -31,7 +31,7 @@ import { getPlaywrightVersion } from '../../utils/userAgent';
 import { urlMatches } from '../../utils/network';
 import { Frame } from '../frames';
 import type { HeadersArray, LifecycleEvent } from '../types';
-import { isTextualMimeType } from '../../utils/mimeType';
+import { isTextualMimeType } from '../../utils/isomorphic/mimeType';
 
 const FALLBACK_HTTP_VERSION = 'HTTP/1.1';
 
@@ -674,4 +674,4 @@ function safeDateToISOString(value: string | number) {
   }
 }
 
-const startedDateSymbol = Symbol('startedDate');
\ No newline at end of file
+const startedDateSymbol = Symbol('startedDate');
diff --git a/packages/playwright-core/src/utils/index.ts b/packages/playwright-core/src/utils/index.ts
index a5219cda6c..67ec09d91d 100644
--- a/packages/playwright-core/src/utils/index.ts
+++ b/packages/playwright-core/src/utils/index.ts
@@ -26,7 +26,7 @@ export * from './headers';
 export * from './hostPlatform';
 export * from './httpServer';
 export * from './manualPromise';
-export * from './mimeType';
+export * from './isomorphic/mimeType';
 export * from './multimap';
 export * from './network';
 export * from './processLauncher';
diff --git a/packages/playwright-core/src/utils/mimeType.ts b/packages/playwright-core/src/utils/isomorphic/mimeType.ts
similarity index 100%
rename from packages/playwright-core/src/utils/mimeType.ts
rename to packages/playwright-core/src/utils/isomorphic/mimeType.ts
diff --git a/packages/trace-viewer/src/ui/attachmentsTab.css b/packages/trace-viewer/src/ui/attachmentsTab.css
index 43291d5f1a..66a94121b5 100644
--- a/packages/trace-viewer/src/ui/attachmentsTab.css
+++ b/packages/trace-viewer/src/ui/attachmentsTab.css
@@ -45,3 +45,7 @@
   max-width: 80%;
   box-shadow: 0 12px 28px 0 rgba(0,0,0,.2), 0 2px 4px 0 rgba(0,0,0,.1);
 }
+
+a.codicon-cloud-download:hover{
+  background-color: var(--vscode-list-inactiveSelectionBackground)
+}
diff --git a/packages/trace-viewer/src/ui/attachmentsTab.tsx b/packages/trace-viewer/src/ui/attachmentsTab.tsx
index 179e6e5c91..f1a5411b8c 100644
--- a/packages/trace-viewer/src/ui/attachmentsTab.tsx
+++ b/packages/trace-viewer/src/ui/attachmentsTab.tsx
@@ -20,9 +20,55 @@ import { ImageDiffView } from '@web/shared/imageDiffView';
 import type { MultiTraceModel } from './modelUtil';
 import { PlaceholderPanel } from './placeholderPanel';
 import type { AfterActionTraceEventAttachment } from '@trace/trace';
+import { CodeMirrorWrapper } from '@web/components/codeMirrorWrapper';
+import { isTextualMimeType } from '@isomorphic/mimeType';
+import { Expandable } from '@web/components/expandable';
 
 type Attachment = AfterActionTraceEventAttachment & { traceUrl: string };
 
+type ExpandableAttachmentProps = {
+  attachment: Attachment;
+};
+
+const ExpandableAttachment: React.FunctionComponent<ExpandableAttachmentProps> = ({ attachment }) => {
+  const [expanded, setExpanded] = React.useState(false);
+  const [loaded, setLoaded] = React.useState(false);
+  const [attachmentText, setAttachmentText] = React.useState<string | null>(null);
+  const [emptyContentReason, setEmptyContentReason] = React.useState<string>('');
+
+  React.useMemo(() => {
+    if (!isTextualMimeType(attachment.contentType)) {
+      setEmptyContentReason('no preview available');
+      return;
+    }
+    if (expanded && !loaded) {
+      setEmptyContentReason('loading...');
+      fetch(attachmentURL(attachment)).then(response => response.text()).then(text => {
+        setAttachmentText(text);
+        setLoaded(true);
+      }).catch(err => setEmptyContentReason('failed to load: ' + err.message));
+    }
+  }, [attachment, expanded, loaded]);
+
+  return <Expandable title={
+    <>
+      {attachment.name}
+      <a href={attachmentURL(attachment) + '&download'}
+        className={'codicon codicon-cloud-download'}
+        style={{ cursor: 'pointer', color: 'var(--vscode-foreground)', marginLeft: '0.5rem' }}
+        onClick={$event => $event.stopPropagation()}>
+      </a>
+    </>
+  } expanded={expanded} expandOnTitleClick={true} setExpanded={exp => setExpanded(exp)}>
+    <div aria-label={attachment.name}>
+      { attachmentText ?
+        <CodeMirrorWrapper text={attachmentText!} readOnly wrapLines={false}></CodeMirrorWrapper> :
+        <i>{emptyContentReason}</i>
+      }
+    </div>
+  </Expandable>;
+};
+
 export const AttachmentsTab: React.FunctionComponent<{
   model: MultiTraceModel | undefined,
 }> = ({ model }) => {
@@ -82,7 +128,7 @@ export const AttachmentsTab: React.FunctionComponent<{
     {attachments.size ? <div className='attachments-section'>Attachments</div> : undefined}
     {[...attachments.values()].map((a, i) => {
       return <div className='attachment-item' key={`attachment-${i}`}>
-        <a href={attachmentURL(a) + '&download'}>{a.name}</a>
+        <ExpandableAttachment attachment={a} />
       </div>;
     })}
   </div>;
diff --git a/tests/playwright-test/ui-mode-test-attachments.spec.ts b/tests/playwright-test/ui-mode-test-attachments.spec.ts
index 71b67e3707..fa685dd612 100644
--- a/tests/playwright-test/ui-mode-test-attachments.spec.ts
+++ b/tests/playwright-test/ui-mode-test-attachments.spec.ts
@@ -25,6 +25,7 @@ test('should contain text attachment', async ({ runUITest }) => {
       test('attach test', async () => {
         await test.info().attach('note', { path: __filename });
         await test.info().attach('🎭', { body: 'hi tester!', contentType: 'text/plain' });
+        await test.info().attach('escaped', { body: '## Header\\n\\n> TODO: some todo\\n- _Foo_\\n- **Bar**', contentType: 'text/plain' });
       });
     `,
   });
@@ -32,13 +33,19 @@ test('should contain text attachment', async ({ runUITest }) => {
   await page.getByTitle('Run all').click();
   await expect(page.getByTestId('status-line')).toHaveText('1/1 passed (100%)');
   await page.getByText('Attachments').click();
-  for (const { name, content } of [
-    { name: 'note', content: 'attach test' },
-    { name: '🎭', content: 'hi tester!' }
+  for (const { name, content, displayedAsText } of [
+    { name: 'note', content: 'attach test', displayedAsText: false },
+    { name: '🎭', content: 'hi tester!', displayedAsText: true },
+    { name: 'escaped', content: '## Header\n\n> TODO: some todo\n- _Foo_\n- **Bar**', displayedAsText: true },
   ]) {
     await page.getByText(`attach "${name}"`, { exact: true }).click();
     const downloadPromise = page.waitForEvent('download');
-    await page.getByRole('link', { name: name }).click();
+    await page.locator('.expandable-title', { hasText: name }).click();
+    await expect(page.getByLabel(name)).toContainText(displayedAsText ?
+      content.split('\n')?.[0] :
+      'no preview available'
+    );
+    await page.locator('.expandable-title', { hasText: name }).getByRole('link').click();
     const download = await downloadPromise;
     expect(download.suggestedFilename()).toBe(name);
     expect((await readAllFromStream(await download.createReadStream())).toString()).toContain(content);
@@ -60,7 +67,7 @@ test('should contain binary attachment', async ({ runUITest }) => {
   await page.getByText('Attachments').click();
   await page.getByText('attach "data"', { exact: true }).click();
   const downloadPromise = page.waitForEvent('download');
-  await page.getByRole('link', { name: 'data' }).click();
+  await page.locator('.expandable-title', { hasText: 'data' }).getByRole('link').click();
   const download = await downloadPromise;
   expect(download.suggestedFilename()).toBe('data');
   expect(await readAllFromStream(await download.createReadStream())).toEqual(Buffer.from([1, 2, 3]));
@@ -81,7 +88,7 @@ test('should contain string attachment', async ({ runUITest }) => {
   await page.getByText('Attachments').click();
   await page.getByText('attach "note"', { exact: true }).click();
   const downloadPromise = page.waitForEvent('download');
-  await page.getByRole('link', { name: 'note' }).click();
+  await page.locator('.expandable-title', { hasText: 'note' }).getByRole('link').click();
   const download = await downloadPromise;
   expect(download.suggestedFilename()).toBe('note');
   expect((await readAllFromStream(await download.createReadStream())).toString()).toEqual('text42');