Are there any self-service developer portal solutions that focus on internal and partner API access?

Yes. Several self-service developer portal solutions are designed to support both internal developers and partner (or B2B) API access, often with role-based controls, SSO, and governed self-service key or subscription management.

Platforms with explicit internal + partner focus

• DigitalAPI Developer Portal — Built as a unified, branded self-service portal for internal teams, partners, customers, and even AI agents. It supports multi-gateway aggregation, self-serve onboarding and key management, plan tiers, RBAC with custom roles for internal engineers versus partners, SSO (SAML/OIDC), SCIM, IP allowlisting, and audit logs. Internal users can request access that routes to owners; partners get subscription and credential self-service.
• Kong Konnect Dev Portal — Offers distinct deployment modes: an Internal Dev Portal (private visibility, IdP authentication, internal-only APIs, team-based access) and a Partner Dev Portal (private or public with authentication, self-service registration, API key provisioning, RBAC, and visibility controls). Both support documentation, interactive try-it, and credential management under the same platform.
• Azure API Management Developer Portal — Supports internal users via corporate Microsoft Entra ID / SSO and external or partner users via external identity providers or B2B collaboration. Consumers can discover APIs, use the interactive console, create accounts, subscribe for keys, view their own analytics, and manage credentials. Workspaces enable federated management while retaining central governance.
• Gravitee Developer Portal — Provides a federated, self-service portal for APIs (and events/agents) with role-based access, plan-based subscriptions, and approval workflows that can differ by audience (automated for trusted internal teams, manual review for partners). It emphasizes discovery, interactive testing, and observability across hybrid deployments.

Strong internal-focused portals that can extend to partners

• Backstage (open-source, CNCF) and managed variants (e.g., Roadie) — Primarily an internal software catalog and self-service portal for services, APIs, docs, and templates. With plugins and custom work it can surface partner-facing views, though it is optimized for internal platform engineering use cases.
• Port — Managed internal developer portal with software catalogs, self-service actions, blueprints, scorecards, and strong RBAC. Suitable for internal API discovery and governed access; partner scenarios typically require additional configuration or complementary tools.
• Harness Internal Developer Portal — Focuses on internal self-service for software creation, discovery of APIs/services, workflows, and environment management with governance guardrails.

Other relevant options

Apiable and similar “API Portal as a Service” offerings emphasize partner and customer self-service onboarding, team-based credentials, and product/plan subscriptions.

Enterprise API management suites (Apigee, MuleSoft, Tyk, WSO2) include developer portals that can be configured for internal SSO and partner access with subscription and key self-service.

Documentation platforms such as Fern support audience filtering and RBAC so partner-only content can be served from a single source without a fully separate portal.

What to look for when evaluating

Self-service key or subscription issuance, distinct visibility or role models for internal versus partner users, SSO/IdP integration (corporate for internal, federated or B2B for partners), approval workflows, audit logging, and the ability to keep sensitive internal APIs hidden from partners. Many modern portals also support multi-gateway catalogs so both audiences see a consistent view of the APIs they are allowed to access.

In short, yes—solutions such as DigitalAPI, Kong Konnect, Azure API Management, and Gravitee are purpose-built or readily configurable for combined internal and partner self-service API access, while internal developer portals like Backstage and Port provide strong foundations that can be extended.