[P1] Audit: JSON Formatter lacks direct download/export of formatted output

[baixiangcpp]

Imported from the byteflow.tools deep audit on 2026-06-22.

Problem: JSON Formatter supports format, minify, copy output, and file import, but the formatted or minified result does not have an obvious direct download/export action. Users who import a JSON file often expect to save the cleaned result as a new .json file.

Affected URL:

• https://byteflow.tools/en/json-formatter

Reproduction steps:

1. Open JSON Formatter.
2. Click Try Example or import a JSON file.
3. Click Format or Minify.
4. Look for a Download or Export JSON action for the output.
5. Attempt to save the formatted output as a local file.

Expected behavior: formatted and minified output should be downloadable as a .json file, with a safe default filename and file size feedback.

Actual behavior: output can be copied, but direct output download is not obvious or unavailable.

Impact: users handling files must copy/paste into another editor, which adds friction and can introduce mistakes.

Proposed fix:

• Add Download Output button beside Copy Output.
• Support .json download for formatted/minified text output.
• Preserve user-selected mode in filename, such as payload.formatted.json or payload.minified.json.
• Show output byte size before download.
• Include tests for valid JSON, invalid JSON, empty output, and imported files.

Acceptance criteria:

• Users can download formatted JSON output directly.
• Download is disabled for empty or invalid output.
• File contents exactly match visible output.
• Works for manual input and imported files.

[baixiangcpp]

Closed as completed by the canonical BF audit backlog work. This older non-BF audit issue duplicates work now merged through PRs #209-#219, with the BF issues closed and guard/test coverage in place. The remaining non-duplicate follow-up is #7, which stays open because the upstream Next/PostCSS advisory is not fixed yet.