diff --git a/README.md b/README.md
index 7c5891c..f6e017f 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ WebMCP is a W3C Draft standard that lets websites expose structured, callable to
 | **WebMCP Core** | 30% | `navigator.modelContext` API, registered imperative tools, schema quality, annotations |
 | **Declarative Forms** | 25% | `toolname`, `tooldescription`, `toolparamdescription`, `toolautosubmit` attributes, form coverage ratio |
 | **Structured Data** | 20% | JSON-LD blocks, `potentialAction` (SearchAction, BuyAction), Product/Offer schema, Organization/WebSite schema |
-| **Discovery & Crawling** | 15% | `/.well-known/webmcp` manifest, `/llms.txt`, `robots.txt` AI crawler rules, sitemaps |
+| **Discovery & Crawling** | 15% | `/.well-known/webmcp` and `/.well-known/webmcp.json` manifest, `/llms.txt`, `robots.txt` AI crawler rules, sitemaps |
 | **Technical Foundation** | 10% | HTTPS, semantic HTML, server-side rendering, stable form IDs |
 | **Security & Consent** | Flags | Sensitive forms with autosubmit, missing consent patterns |
 
diff --git a/claude-skill/webmcp-audit.md b/claude-skill/webmcp-audit.md
index 02fa012..13035a6 100644
--- a/claude-skill/webmcp-audit.md
+++ b/claude-skill/webmcp-audit.md
@@ -38,7 +38,9 @@ For each URL, use WebFetch to retrieve:
 
 4. **`{origin}/.well-known/webmcp`** — check if it exists and extract manifest content
 
-Make all 4 fetch requests for each URL.
+5. **`{origin}/.well-known/webmcp.json`** — check if it exists and extract manifest content (alternative proposed standard)
+
+Make all 5 fetch requests for each URL.
 
 ## Step 2: Score the page
 
@@ -78,7 +80,7 @@ Apply the following scoring rubric. Each category has a weight and individual si
 
 | Signal | How to detect | Points (out of 15) |
 |--------|--------------|---------------------|
-| `/.well-known/webmcp` manifest exists | Successful fetch with valid JSON | 5 |
+| `/.well-known/webmcp` or `/.well-known/webmcp.json` manifest exists | Successful fetch with valid JSON from either endpoint | 5 |
 | `/llms.txt` exists | Successful fetch with markdown content | 4 |
 | `robots.txt` allows AI crawlers | No blocks for GPTBot, Google-Extended, ClaudeBot | 4 |
 | Sitemap referenced in robots.txt | `Sitemap:` directive present | 2 |
@@ -132,6 +134,7 @@ Apply the following scoring rubric. Each category has a weight and individual si
 
 ## Discovery Files
 - {status icon} /.well-known/webmcp — {status detail}
+- {status icon} /.well-known/webmcp.json — {status detail}
 - {status icon} /llms.txt — {status detail}
 - {status icon} robots.txt — {AI crawler status detail}
 
diff --git a/extension/background.js b/extension/background.js
index e5e8dc4..35c688e 100644
--- a/extension/background.js
+++ b/extension/background.js
@@ -5,7 +5,7 @@
  * Responsibilities:
  *  - Open the side panel when the extension icon is clicked.
  *  - Update the badge based on scan results from the content script.
- *  - Fetch discovery files (robots.txt, llms.txt, .well-known/webmcp).
+ *  - Fetch discovery files (robots.txt, llms.txt, .well-known/webmcp, .well-known/webmcp.json).
  *  - Inject a MAIN-world script to detect navigator.modelContext.
  *  - Route messages between the content script and the side panel.
  *  - Auto-scan on navigation and SPA history changes.
@@ -76,17 +76,18 @@ async function fetchFile(url) {
 }
 
 /**
- * Fetch all three discovery files for a given origin.
+ * Fetch all discovery files for a given origin.
  * @param {string} origin - e.g. "https://example.com"
- * @returns {Promise<{ robots: object, llms: object, webmcp: object }>}
+ * @returns {Promise<{ robots: object, llms: object, webmcp: object, webmcpJson: object }>}
  */
 async function fetchDiscoveryFiles(origin) {
-  const [robots, llms, webmcp] = await Promise.all([
+  const [robots, llms, webmcp, webmcpJson] = await Promise.all([
     fetchFile(`${origin}/robots.txt`),
     fetchFile(`${origin}/llms.txt`),
     fetchFile(`${origin}/.well-known/webmcp`),
+    fetchFile(`${origin}/.well-known/webmcp.json`),
   ]);
-  return { robots, llms, webmcp };
+  return { robots, llms, webmcp, webmcpJson };
 }
 
 // ---------------------------------------------------------------------------
@@ -190,7 +191,7 @@ async function handleRequestScan(message) {
 
 /**
  * Handle FETCH_DISCOVERY requests.
- * Fetches robots.txt, llms.txt, and .well-known/webmcp for the given origin.
+ * Fetches robots.txt, llms.txt, .well-known/webmcp, and .well-known/webmcp.json for the given origin.
  * @param {object} message
  * @param {function} sendResponse
  */
diff --git a/extension/content.js b/extension/content.js
index f3e6bc5..7193b7d 100644
--- a/extension/content.js
+++ b/extension/content.js
@@ -348,19 +348,22 @@ function buildDiscoveryPlaceholder() {
 
 /**
  * Fill discovery category with data returned from the background script.
- * @param {{ robots: object, llms: object, webmcp: object }} discovery
+ * @param {{ robots: object, llms: object, webmcp: object, webmcpJson: object }} discovery
  * @returns {{ score: number, max: number, signals: Array }}
  */
 function fillDiscovery(discovery) {
   const signals = [];
   let score = 0;
 
-  // webmcp manifest (5 pts)
-  if (discovery.webmcp?.status === 200 && discovery.webmcp.content) {
+  // webmcp manifest (5 pts) — check .well-known/webmcp or .well-known/webmcp.json
+  const hasWebmcp = discovery.webmcp?.status === 200 && discovery.webmcp.content;
+  const hasWebmcpJson = discovery.webmcpJson?.status === 200 && discovery.webmcpJson.content;
+  if (hasWebmcp || hasWebmcpJson) {
+    const found = [hasWebmcp && '.well-known/webmcp', hasWebmcpJson && '.well-known/webmcp.json'].filter(Boolean).join(' and ');
     score += 5;
-    signals.push(signal('webmcp manifest', 'pass', '.well-known/webmcp found', 5));
+    signals.push(signal('webmcp manifest', 'pass', `${found} found`, 5));
   } else {
-    signals.push(signal('webmcp manifest', 'fail', 'No .well-known/webmcp', 0));
+    signals.push(signal('webmcp manifest', 'fail', 'No .well-known/webmcp or .well-known/webmcp.json', 0));
   }
 
   // llms.txt (4 pts)
@@ -675,7 +678,7 @@ function generateRecommendations(categories, forms, tools) {
   }
   const noManifest = disc.find((s) => s.name === 'webmcp manifest' && s.status === 'fail');
   if (noManifest) {
-    recs.push('Create a /.well-known/webmcp manifest listing your agent-accessible tools.');
+    recs.push('Create a /.well-known/webmcp or /.well-known/webmcp.json manifest listing your agent-accessible tools.');
   }
 
   // Missing tooldescription on tools
diff --git a/extension/sidepanel.js b/extension/sidepanel.js
index 206922c..aed4394 100644
--- a/extension/sidepanel.js
+++ b/extension/sidepanel.js
@@ -87,7 +87,7 @@ const FIX_SNIPPETS = {
 - [Cart](https://example.com/cart): Manage shopping cart`,
   },
   webmcp_manifest: {
-    desc: 'Create a /.well-known/webmcp manifest describing available tools.',
+    desc: 'Create a /.well-known/webmcp or /.well-known/webmcp.json manifest describing available tools.',
     code: `{
   "schema_version": "0.1",
   "name_for_model": "example_site",