Add custom developer portals doc

deploy/custom-portal.mdx

@@ -0,0 +1,80 @@
+---
+title: "Custom developer portals"
+description: "Deploy a fully custom developer portal on top of self-hosted Mintlify, designed and built by Mintlify and delivered through versioned releases."
+keywords: ["developer portal", "custom presentation layer", "API marketplace", "self-host", "on-prem", "white label", "enterprise"]
+---
+
+<Info>
+  Custom portals require an [Enterprise plan](https://mintlify.com/pricing?ref=custom-portal) and a [self-hosted deployment](/deploy/self-host). Reach out to your account team to scope one.
+</Info>
+
+For some platforms, documentation is one surface of a larger product—an API marketplace, a partner portal, or a developer experience with sign-in, credentials, and support built in. Mintlify supports those use cases by designing, building, and maintaining a  custom presentation layer that replaces your existing portal front end, while your team authors content through the Mintlify editor or a Git-backed workflow.
+
+The portal integrates with your existing APIs, gateway, and downstream systems, which remain owned and operated by your team.
+
+## Features
+
+| Feature | What ships | Backed by |
+| --- | --- | --- |
+| Custom presentation layer | A full front-end application in your design system, deployed inside your environment | Mintlify, alongside the self-hosted platform |
+| Product and catalog pages | Marketplace, product discovery, and documentation surfaces | Content maintained on Mintlify |
+| Sign-in | Authenticated sessions across the portal | Your identity provider |
+| Applications and credentials | Application registration and credential management | Your backend APIs |
+| Subscriptions | Product and plan subscriptions | Your backend APIs |
+| Profiles and notifications | User profiles and notification centers | Your backend APIs |
+| Support | Support ticket creation and tracking | Your backend APIs |
+| Search | Login-aware search scoped to what the user can access | Mintlify platform |
+| Personalized content | Entitlement and group-based filtering applied server-side at render time, so users only see the products and pages they have access to | Mintlify platform and your identity provider |
+| Ongoing releases | Versioned releases with upgrade guides, the same operating model as any [self-hosted deployment](/deploy/self-host#updates) | Mintlify |
+
+## Authoring flow
+
+The custom front end doesn't affect how content gets written. Maintain content with the editor or a local Git-based workflow. Every change flows through your repository's review process with a full audit trail, and publishing triggers builds that update the portal automatically. Content changes do not require a front-end deploy.
+
+## Architecture
+
+The custom presentation layer integrates with the self-hosted Mintlify platform for content, search, and personalization; your API gateway for applications, subscriptions, and support; and your identity provider for authentication.
+
+```mermaid
+flowchart TD
+  U[Users] --> CDN[CDN and WAF]
+  CDN --> PORTAL[Custom presentation layer]
+  PORTAL --> PLAT[Mintlify platform<br/>content, search, personalization]
+  PORTAL --> GW[Your API gateway]
+  GW --> BE[Your backend services<br/>applications, subscriptions, support]
+  PORTAL --> IDP[Your identity provider]
+  W[Writers] --> ED[Editor and Git workflow]
+  ED --> PLAT
+```
+
+The custom presentation layer and Mintlify platform run inside your network boundary, using your cluster, data stores, and observability stack, with no third-party egress. Your downstream systems of record remain unchanged; the portal accesses them through your existing APIs.
+
+## How the engagement runs
+
+<Steps>
+  <Step title="Scope and design">
+    Your account team maps the portal surfaces, your design system, and the backend APIs the portal consumes, and agrees on an integration contract with your platform team.
+  </Step>
+  <Step title="Public surfaces first">
+    The engagement typically implements your design system and public content surfaces first, so you can validate the experience against your existing portal before cutover.
+  </Step>
+  <Step title="Authenticated surfaces">
+    Sign-in, credential management, subscriptions, and other logged-in experiences follow, integrated with your identity provider and backend APIs.
+  </Step>
+  <Step title="Search, personalization, and AI">
+    Login-aware search and server-side personalization complete the core experience. Optional AI features remain disabled disabled until your security or AI governance team approves them.
+  </Step>
+</Steps>
+
+Throughout, your team reviews releases in non-production environments and controls every cutover.
+
+## Next steps
+
+<Columns cols={2}>
+  <Card title="Talk to your account team" icon="messages-square" href="https://www.mintlify.com/enterprise">
+    Scope a custom portal engagement and plan your launch.
+  </Card>
+  <Card title="Self-host" icon="server" href="/deploy/self-host">
+    The deployment foundation a custom portal runs on.
+  </Card>
+</Columns>

docs.json

@@ -221,7 +221,8 @@
                   "deploy/ghes",
                   "deploy/gitlab",
                   "deploy/gitlab-self-hosted",
-                  "deploy/self-host"
+                  "deploy/self-host",
+                  "deploy/custom-portal"
                 ]
               },
               {