Add Similarweb third-party MCP plugin

Similarweb's hosted MCP server speaks Streamable HTTP but authenticates with a user-supplied token rather than OAuth, so the plugin declares a variable and forwards it as an HTTP header.

Co-authored-by: Roshan Sadanani <roshansada@users.noreply.github.com>

.cursor-plugin/marketplace.json

@@ -297,6 +297,11 @@
       "name": "readwise",
       "source": "third_party/readwise",
       "description": "Search highlights and Reader documents, save articles."
+    },
+    {
+      "name": "similarweb",
+      "source": "third_party/similarweb",
+      "description": "Analyze website traffic, audiences, and competitors."
     }
   ]
 }

README.md

@@ -64,6 +64,7 @@ Official Cursor plugins for popular developer tools, frameworks, and SaaS produc
 | `craft` | [Craft](third_party/craft/) | Cursor | Integrations | Search, create, and update documents and daily notes. |
 | `mem` | [Mem](third_party/mem/) | Cursor | Integrations | Capture, search, and organize notes and collections. |
 | `readwise` | [Readwise](third_party/readwise/) | Cursor | Integrations | Search highlights and Reader documents, save articles. |
+| `similarweb` | [Similarweb](third_party/similarweb/) | Cursor | Integrations | Analyze website traffic, audiences, and competitors. |
 Author values match each plugin’s `plugin.json` `author.name` (Cursor lists `plugins@cursor.com` in the manifest).
 
 ## Repository structure

third_party/similarweb/.cursor-plugin/plugin.json

@@ -0,0 +1,46 @@
+{
+  "name": "similarweb",
+  "displayName": "Similarweb",
+  "version": "1.0.0",
+  "minClientVersions": {
+    "cursor": "3.13.0"
+  },
+  "description": "Analyze website traffic, audiences, and competitors.",
+  "author": {
+    "name": "Cursor",
+    "email": "plugins@cursor.com"
+  },
+  "homepage": "https://docs.similarweb.com/api-v5/similarweb-mcp",
+  "repository": "https://github.com/cursor/plugins",
+  "license": "MIT",
+  "logo": "assets/logo.png",
+  "keywords": [
+    "similarweb",
+    "traffic",
+    "analytics",
+    "competitive-intelligence",
+    "audience",
+    "mcp"
+  ],
+  "category": "integrations",
+  "tags": [
+    "similarweb",
+    "analytics",
+    "mcp",
+    "research"
+  ],
+  "variables": {
+    "type": "object",
+    "properties": {
+      "SIMILARWEB_API_KEY": {
+        "type": "string",
+        "title": "Similarweb API key",
+        "description": "REST API key from Similarweb under Account Settings \u2192 Data Tools \u2192 REST API."
+      }
+    },
+    "required": [
+      "SIMILARWEB_API_KEY"
+    ]
+  },
+  "mcpServers": "./mcp.json"
+}

third_party/similarweb/CHANGELOG.md

@@ -0,0 +1,9 @@
+# Changelog
+
+All notable changes to this plugin will be documented here.
+
+## 1.0.0 — initial release
+
+- Added the `similarweb` MCP server pointing at `https://mcp.similarweb.com`.
+- Auth uses a Similarweb API key supplied by the user as a request header.
+- Logo: Similarweb's official mark, from the `similarweb` GitHub organization.

third_party/similarweb/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Cursor
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

third_party/similarweb/README.md

@@ -0,0 +1,63 @@
+# Similarweb
+
+Cursor plugin that connects agents to [Similarweb](https://www.similarweb.com) through Similarweb's official remote [Model Context Protocol](https://modelcontextprotocol.io/) server.
+
+Pull Similarweb digital-intelligence data — website traffic and engagement, competitor comparison, audience demographics, and keyword metrics — for research without leaving the editor.
+
+## Install
+
+1. Open **Cursor Settings → Plugins**.
+2. Search for **Similarweb**.
+3. Click **Install**, then set your Similarweb API key (below).
+
+Or run `/add-plugin similarweb` in chat.
+
+## MCP
+
+```json
+{
+  "mcpServers": {
+    "similarweb": {
+      "type": "http",
+      "url": "https://mcp.similarweb.com",
+      "headers": {
+        "api-key": "${SIMILARWEB_API_KEY}"
+      }
+    }
+  }
+}
+```
+
+Auth is a Similarweb **API key** sent in an `api-key` header (lowercase, hyphenated — not `Authorization`). Copy it from **Account Settings → Data Tools → REST API**, then set it in **Dashboard → Plugins → Configure**.
+
+## Before you connect
+
+You need a Similarweb subscription with API access — API-only, Business, or Enterprise. Calls debit standard API data credits. If the REST API section is not visible in your account settings, an account admin has to generate the key.
+
+## What agents can do
+
+| Category | Capabilities |
+| --- | --- |
+| Web metrics | Traffic and engagement, traffic sources, website rank, similar sites, referrals, audience overlap, demographics, technologies, segments, and PPC spend |
+| Search metrics | SERP players and SERP clicks |
+| App metrics | App install penetration, app store rank, and app details |
+
+The hosted runtime is the source of truth for tool names and schemas.
+
+## Notes
+
+- Tool calls run with the permissions and credit balance attached to the API key.
+- Similarweb's own Cursor guide routes through `npx mcp-remote`. That is not necessary — Cursor connects to the remote endpoint directly and sends the `api-key` header, which is the same shape Similarweb documents for Microsoft Copilot Studio.
+- Similarweb runs two documentation portals, `docs.similarweb.com` and `developers.similarweb.com`, whose MCP paths drift. Both give the same endpoint.
+
+## Docs
+
+- Similarweb MCP: https://docs.similarweb.com/api-v5/similarweb-mcp
+- Similarweb MCP (developer portal): https://developers.similarweb.com/docs/similarweb-mcp
+- Server URL: https://mcp.similarweb.com
+
+Logo is Similarweb's official mark, from the `similarweb` GitHub organization.
+
+## License
+
+MIT

third_party/similarweb/mcp.json

@@ -0,0 +1,11 @@
+{
+  "mcpServers": {
+    "similarweb": {
+      "type": "http",
+      "url": "https://mcp.similarweb.com",
+      "headers": {
+        "api-key": "${SIMILARWEB_API_KEY}"
+      }
+    }
+  }
+}