For software teams that sell to enterprises, supporting single sign-on (SSO) through customer-managed identity providers is a requirement — but testing those integrations has long been a painful bottleneck. Traditionally, developers have needed to request access to test tenants, coordinate with customers’ IT teams, and expose local servers to the internet just to run a basic login flow. Even then, only the so-called “happy path” gets tested; real-world failures like expired assertions or forged signatures rarely get a look-in until a security review — or worse, a production incident.
SSOJet’s mock-idp changes that equation entirely. This free, open-source tool runs nine popular identity providers — including Okta, Microsoft Entra ID, Google Workspace, OneLogin, PingOne, JumpCloud, Microsoft AD FS, Auth0, and Keycloak — inside a single Docker container. It lets developers simulate any of those providers on their laptop, test SAML, OIDC, and SCIM integrations, and then deliberately inject more than 40 different faults to see if the application handles them correctly. Available at GitHub under the MIT license, mock-idp is a game-changer for any B2B SaaS team.
What Is mock-idp?
mock-idp is a self-contained identity provider simulator designed to help developers test enterprise authentication and provisioning without needing real vendor tenants. It runs as a single Docker image and presents a web dashboard with nine pre-configured demo companies, each with users, groups, and two test applications. Developers can immediately test SAML login flows using the built-in service provider, which shows every check performed in real time.
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Beyond basic login, mock-idp supports the full range of enterprise SSO features: SAML 2.0 with encrypted assertions, signed authentication requests, and single logout; OpenID Connect with authorization code flow, PKCE, refresh tokens, and client credentials; and SCIM provisioning that pushes users and groups just like Okta or Microsoft Entra ID would. A conformance test suite for SCIM is also included, along with live logs that decode every SAML response and JSON Web Token for debugging.
What Stands Out
Nine Providers, One Container
Rather than spinning up separate test environments for each identity provider, mock-idp bundles all nine in a single container. Each simulated provider reproduces documented behaviors of the real service — for example, Microsoft Entra ID issuing a different user identifier per application, or Okta using a different SAML issuer per app. This fidelity means teams can test provider-specific quirks without ever signing up for a vendor dev org.
Fault Injection for Real-World Testing
The standout feature is the fault injection system. Developers can toggle any of 40+ faults, including expired assertions, XML signature-wrapping attacks, unsigned tokens, unknown signing keys, clock skew, and an identity provider that returns errors. This allows teams to verify that their application rejects broken or malicious logins, not just the happy path. SSOJet demonstrated the importance of this by testing four popular open-source SSO libraries — finding several gaps, such as a library accepting a tampered ID token and another not checking the issuer of a SAML login response.
CI and AI Integration
mock-idp provides a JSON API and an MCP (Model Context Protocol) server, so it fits naturally into continuous integration pipelines and AI agent workflows. Teams can programmatically create tenants, inject faults, and read results — all without any manual setup. This makes regression testing of SSO integrations as routine as running unit tests.
Who It’s For
mock-idp is built for engineering teams at B2B SaaS companies that need to support enterprise SSO. Whether the team is integrating SAML for the first time or hardening existing OIDC support, the tool eliminates the friction of coordinating with external IT departments. It is equally valuable for security engineers who want to validate that authentication code resists common attacks, and for QA teams who need a reproducible way to test edge cases in CI. The free, open-source nature means even small startups can adopt it without budget concerns.
Pricing and Availability
mock-idp is completely free and open source under the MIT license. There are no paid tiers, no usage limits, and no feature gates. It runs on both Intel and Arm architectures with a single Docker command: docker run -p 7070:7070 ghcr.io/ssojet/mock-idp. The source code, documentation, and findings from the library report card are all available on the project’s GitHub repository. There is no need to sign up or provide payment information — just pull the image and start testing.
What Makes It Worth Considering
First, mock-idp directly addresses a pain point that every enterprise-facing SaaS team knows: the difficulty of testing SSO integrations thoroughly. By simulating nine identity providers and offering fault injection, it lets developers catch failure modes before customers’ security reviews do. Second, the tool is not just a proof of concept — it was built by SSOJet to test their own product, and the team has already used it to discover real bugs in widely used open-source SSO libraries. The transparency of publishing those findings adds to the tool’s credibility.
Third, the integration with CI and AI agents means that testing is not a one-time activity but can be automated as part of the development workflow. Finally, the zero-cost entry removes any financial barrier, making high-quality SSO testing accessible to teams of any size. For any company shipping software that relies on SAML, OIDC, or SCIM, mock-idp is a practical and generous contribution to the developer community.
Verdict
mock-idp is a must-have free tool for any B2B SaaS team that needs to test enterprise SSO reliably and securely before customers do. Its combination of realistic provider simulation, extensive fault injection, and CI-ready APIs raises the bar for authentication testing. The fact that it is open source and completely free makes it an easy recommendation for both startups and established organizations. For teams serious about enterprise readiness, this is one of the most valuable testing tools to appear this year.
Frequently asked questions
mock-idp is a free open-source identity provider simulator from SSOJet that runs nine providers locally for testing SAML, OIDC, and SCIM integrations.
It simulates Okta, Microsoft Entra ID, Google Workspace, OneLogin, PingOne, JumpCloud, Microsoft AD FS, Auth0, and Keycloak.
Run a single Docker command: docker run -p 7070:7070 ghcr.io/ssojet/mock-idp, then open http://localhost:7070.
Yes, it includes 40+ injectable faults such as expired assertions, signature-wrapping attacks, and clock skew.
Yes, it is completely free and released under the MIT open-source license.
Yes, it provides a JSON API and an MCP server for integration with continuous integration and AI agents.
It was created by SSOJet, a company that provides enterprise SSO and directory sync solutions for B2B SaaS.
