add json diff

.github/workflows/lighthouse.yml

@@ -27,6 +27,9 @@ jobs:
       - name: Test cron parsing and schedule evaluation
         run: node --test scripts/crontab.test.cjs
 
+      - name: Test JSON and YAML comparison
+        run: node --test scripts/json-diff.test.cjs
+
       - name: Validate HTML
         uses: Cyb3r-Jak3/html5validator-action@v7.2.0
         with:
@@ -51,6 +54,7 @@ jobs:
             kubernetes-rbac-explorer/index.html
             visual-subnet-calculator/index.html
             yaml-formatter/index.html
+            json-diff/index.html
             crontab/index.html
             terraform-modules/index.html
           fail: true
@@ -76,5 +80,6 @@ jobs:
             http://127.0.0.1:8080/kubernetes-rbac-explorer/
             http://127.0.0.1:8080/visual-subnet-calculator/
             http://127.0.0.1:8080/yaml-formatter/
+            http://127.0.0.1:8080/json-diff/
             http://127.0.0.1:8080/crontab/
             http://127.0.0.1:8080/terraform-modules/

README.md

@@ -91,6 +91,50 @@ The shorter `/json-formatter/` alias redirects to this tool.
 YAML parsing and serialization use the vendored `js-yaml` 4.1.0 browser
 bundle, distributed under the MIT license included with the tool.
 
+## JSON & YAML Diff Checker
+
+Open `/json-diff/` to compare JSON, JSON-compatible YAML, or one of each entirely
+in the browser. Structural comparison ignores object key order, formatting, and
+YAML comments, and reports added, removed, and changed values by field path.
+Arrays can compare by position, as unordered multisets, or by a unique direct
+object field. Kubernetes mode matches multi-document YAML or JSON resource
+arrays by API version, kind, namespace, and name.
+
+The page reuses the formatter's header/footer markup, theme stylesheet, and
+vendored MIT-licensed js-yaml parser. Inputs are never uploaded or persisted.
+File import, individual format selection, formatting, swapping, filtering,
+copying, and complete JSON report downloads work locally. Editing inputs or
+comparison options invalidates the previous report immediately. Live comparison
+refreshes after a short typing pause and can be switched off for manual reviews.
+Editable source views highlight the affected lines and values, with matching
+gutter markers, live counts, Previous/Next navigation, and Alt+Up/Down shortcuts.
+Source locations follow JSON/YAML structure, keyed arrays, aliases, and reordered
+Kubernetes resources. Only the visible editor lines are rendered in the highlight
+layer so long documents remain practical to navigate.
+Results offer side-by-side and unified layouts, syntax coloring, inline value
+highlights, and readable Kubernetes resource labels alongside the original
+report paths.
+
+Each input is limited to 1 MiB, 80 nesting levels, and 50,000 expanded values;
+expanded text is capped at 4 MiB and reports at 2,000 changes. Duplicate mapping
+keys, recursive aliases, non-finite numbers, and unsafe integers are rejected.
+Numbers otherwise use JavaScript precision. Match paths are descriptive report
+labels, not JSON Patch operations. Large value previews are shortened; exports
+retain complete values.
+
+Run the comparison regression tests:
+
+```sh
+node --test scripts/json-diff.test.cjs
+```
+
+The page includes indexable JSON and YAML examples, instructions, FAQs, section
+navigation, related-tool links, and connected page/application/author/image
+structured data. `python3 scripts/seo-audit.py` checks metadata agreement,
+canonical URLs, schema relationships, examples, incoming links, and sitemap
+dates. Follow the JSON diff section in [`SEARCH_CONSOLE.md`](./SEARCH_CONSOLE.md)
+after deployment to inspect indexing and measure search performance.
+
 ## Kubernetes RBAC Explorer
 
 Open `/kubernetes-rbac-explorer/` to turn Kubernetes Roles and bindings into
@@ -226,6 +270,7 @@ python3 -m http.server 8080
 - `http://localhost:8080/kubernetes-rbac-explorer/`
 - `http://localhost:8080/visual-subnet-calculator/`
 - `http://localhost:8080/yaml-formatter/`
+- `http://localhost:8080/json-diff/`
 - `http://localhost:8080/crontab/`
 - `http://localhost:8080/terraform-modules/`
 

SEARCH_CONSOLE.md

@@ -37,6 +37,7 @@ invented or replaced with a placeholder.
    - `https://native-cube.com/kubernetes-rbac-explorer/`
    - `https://native-cube.com/visual-subnet-calculator/`
    - `https://native-cube.com/yaml-formatter/`
+   - `https://native-cube.com/json-diff/`
    - `https://native-cube.com/crontab/`
    - `https://native-cube.com/terraform-modules/`
 4. Do not submit `/json-formatter/`; it is a redirect alias.
@@ -173,6 +174,35 @@ workflow. Shared schedules remain URL fragments and retain the same clean
 canonical, following Google's
 [canonicalization guidance](https://developers.google.com/search/docs/crawling-indexing/consolidate-duplicate-urls).
 
+## Check and measure the JSON and YAML diff page
+
+After publishing `/json-diff/`:
+
+1. Inspect `https://native-cube.com/json-diff/` with **Test live URL**. Confirm an
+   indexable HTTP 200 response and the exact canonical URL with its trailing
+   slash. Submit that canonical URL for indexing after the live checks pass.
+2. Check the original HTML and the rendered page. The heading, comparison
+   instructions, JSON and YAML examples, FAQ, related tools, and ordinary
+   navigation links are static HTML. Only comparison and highlighting require
+   JavaScript. Confirm that the live editor still works on desktop and mobile.
+3. Validate the linked `WebPage`, `WebApplication`, `BreadcrumbList`, `Person`,
+   and `ImageObject` entities with the
+   [Schema Markup Validator](https://validator.schema.org/) and
+   [Rich Results Test](https://search.google.com/test/rich-results). Keep the
+   feature list accurate. The page does not publish ratings or reviews; do not
+   invent them to remove rich-result eligibility warnings.
+4. In the Search Console performance report, filter to the exact page URL.
+   Monitor impressions, clicks, CTR, and position for JSON diff, JSON compare,
+   YAML diff, compare YAML files, and Kubernetes manifest comparison queries.
+   These are query groups to investigate, not verified search volumes or
+   ranking predictions. Check actual indexing and selected canonical in Search
+   Console; passing local checks cannot establish either.
+5. Keep `WebPage.dateModified` and sitemap `lastmod` aligned when content changes.
+   The local SEO audit enforces their agreement, page and social metadata,
+   schema relationships, static examples, and incoming links from the homepage
+   and formatter. Run `python3 scripts/check-redirects.py` after deployment to
+   verify the published redirects and canonical destinations.
+
 ## Keep sitemap dates accurate
 
 Update a page's `lastmod` when its public content or metadata changes. The