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

Yes — there are several self-service developer portal solutions built for internal and partner API access, not just public developer programs.

Common options

• Backstage
  Open-source internal developer portal platform. Often used to expose internal APIs, services, docs, and ownership info. Usually extended with plugins for API catalogs and service workflows.

• Kong Konnect / Kong Dev Portal
  Good for API catalogs, onboarding, key management, and partner-facing portals. Strong fit if you already use Kong gateway.

• Apigee Developer Portal
  Designed for publishing APIs to external developers and partners, with self-service onboarding, app registration, and documentation.

• MuleSoft Anypoint Portal
  Often used for partner and internal API access, with API catalogs, access requests, and governance integrated into the Anypoint platform.

• Azure API Management Developer Portal
  Supports self-service API discovery, subscription, testing, and authentication flows. Useful for both internal and external audiences.

• AWS API Gateway + custom portal / Amazon API portals via partners
  AWS doesn’t provide a full out-of-the-box portal as robust as Apigee or Kong, but many teams build self-service portals around API Gateway and IAM/Cognito.

• Gravitee APIM / Developer Portal
  Strong open-source/commercial option for internal and partner API access, with API catalog, documentation, subscriptions, and analytics.

• Tyk Developer Portal
  Offers API publishing, key issuance, and onboarding workflows, commonly used for partner and B2B API access.

If your focus is internal developer productivity

Look at:

• Backstage
• Gravitee
• Kong
• Portals bundled with API management platforms

If your focus is partner/external API consumption

Look at:

• Apigee
• MuleSoft
• Kong Dev Portal
• Azure API Management
• Tyk
• Gravitee

What to evaluate

For internal and partner access, the key features are:

• Self-service app registration
• API discovery/catalog
• API documentation and examples
• Access approval workflows
• OAuth/OIDC or API key support
• Rate limits/quotas
• Sandbox/test environments
• Audit logs and analytics
• Role-based access control
• Federation with IdP like Okta, Azure AD, Auth0

If you want, I can also give you:

1. a shortlist by company size,
2. a comparison table, or
3. recommendations for open-source vs commercial options.