Open Source vs SaaS Identity Platforms: Weighing the Pros and Cons

Introduction

This blog was inspired by a recent conversation with my account manager at Kong, who explained how the company will govern its Open Source distribution model from version 3.9 onwards. That triggered me to reflect more broadly on how Open Source projects are governed, and how organizations should weigh the differences between Open Source (self-managed) and SaaS (vendor-managed) identity platforms.

The relevance is clear: identity systems underpin authentication, authorization, and integration across modern infrastructures. They are also at the center of discussions around compliance, sovereignty, and vendor lock-in. With growing regulatory pressure in Europe, the rise of AI-driven workloads, and an increase in licensing shifts among major projects, the decision between these two models has far-reaching implications for security, compliance, cost, and long-term flexibility.

In this article, I outline the advantages and disadvantages of both approaches across support, security, compliance & audits, licensing, and software lifecycle. My goal is not to promote one side, but to highlight what organizations need to examine carefully before committing.

1. Support

• SaaS
  • Advantage: Responsibilities for documentation, upgrades, incident response, and lifecycle management are contractually assigned to the vendor. Service commitments are defined in SLAs and support terms.
  • Disadvantage: Dependency on the vendor’s roadmap, pricing, and deprecation policies. Migration can be time-consuming and costly.
• Open Source (self-managed)
  • Advantage: Transparency and the option to modify or patch code in-house. Community forums, issue trackers, and discussions can provide valuable peer support.
  • Disadvantage: Most repositories include a clear disclaimer—use at your own risk. OSS licenses typically disclaim warranty and liability, and continuity depends on internal capacity or paid third-party support. There are no guaranteed response times.

2. Security Hardening

• SaaS
  • Advantage: Vendors typically operate a centralized security program: periodic penetration testing, red-team exercises, SAST/DAST security testing, software composition analysis (SCA), vulnerability management, and monitored patch pipelines. Patch/service windows and vulnerability handling are usually documented.
  • Disadvantage: Limited visibility into the depth of testing and remediation timelines beyond what is shared in trust centers or audit reports. Verification relies on contractual rights to reports and audits.
• Open Source (self-managed)
  • Advantage: Full control over hardening standards and audit scope; you can tailor testing to internal policies (e.g., CIS benchmarks, custom threat models).
  • Disadvantage: Your team must plan and execute testing, track vulnerabilities (including upstream CVEs), and apply patches promptly—requiring specialized skills and sustained capacity.

3. Compliance & Audits

• SaaS
  • Advantage: Established providers often maintain third-party attestations (e.g., ISO 27001, SOC 2) and GDPR-related documentation (e.g., DPA, subprocessor lists). These artifacts can reduce evidence-collection effort for your audits.
  • Disadvantage: Certifications vary by product, region, and scope and can change over time. Your organization remains the data controller (where applicable) and retains regulatory accountability. Always review current certificates, scope statements, and audit rights.
• Open Source (self-managed)
  • Advantage: Maximum configurability to meet specific regulatory controls (e.g., logging/retention, key management, segregation of duties).
  • Disadvantage: You must design, implement, and evidence all controls yourself (policies, procedures, monitoring, segregation of environments, change management). External audits are fully your responsibility.

4. Licensing

• SaaS
  • Advantage: Access is governed by subscription agreements with defined usage rights and support terms.
  • Disadvantage: Cost scales with usage; switching costs can be high if proprietary features are deeply embedded.
• Open Source (self-managed)
  • Advantage: Common OSS licenses (e.g., Apache-2.0, MIT, GPL) allow use and modification with few or clearly defined obligations.
  • Disadvantage: Some widely used projects have moved from permissive/FOSS to source-available or more restrictive licenses in recent years (e.g., SSPL, BUSL, RSAL). These shifts can affect hosting, resale, or integration rights and may necessitate forks or re-platforming. Examples: MongoDB (SSPL, 2018), Elastic’s Elasticsearch/Kibana (SSPL/Elastic License, 2021), HashiCorp products (BUSL, 2023), Redis (RSAL/SSPL dual-license from 7.4, 2024). Always review the current license text and version policy before adopting.

5. Software Development & Lifecycle

• SaaS
  • Advantage: The vendor manages building, packaging, integration testing, upgrades, bug fixes, and patches. Customers typically manage only configuration and integrations on top.
  • Disadvantage: Limited influence over prioritization and release timing; custom features may be infeasible.
• Open Source (self-managed)
  • Advantage: Full autonomy over branching, extensions, and release cadence.
  • Disadvantage: You own builds, CI/CD, regression testing, dependency management, and patch pipelines—incurring ongoing engineering and QA effort.

6. Community vs. Vendor Accountability

• Open Source (self-managed): Community health (maintainers, cadence of releases, issue response) is a key risk factor. Continuity is not contractually guaranteed unless you purchase commercial support.
• SaaS: Accountability is contractual (SLAs, support terms, data processing agreements). Verify exit options (data export formats, migration tooling) and deprecation policies.

Conclusion & Practical Guidance

The decision between Open Source and SaaS identity platforms balances control versus assurance and the capacity to carry non-functional responsibilities (security, compliance, upgrades).

• Choose Open Source (self-managed) if you need deep customization or sovereignty and can allocate a dedicated team covering platform engineering, security, and compliance. As an indicative benchmark for medium-to-large deployments with multiple integrations, plan for ~5–10 experienced engineers across DevOps/SRE, AppSec, and QA. Scale with system complexity, uptime targets, and audit scope.
• Choose SaaS if you prefer predictable operations and shared-responsibility clarity, and want to focus internal capacity on configuration and business integrations. Ensure you have audit rights, current certifications, and clear data-portability options.

Regardless of the model, your organization remains accountable for identity-related risks and regulatory obligations. Perform a formal risk assessment, verify licensing terms, review audit evidence, and document exit and upgrade strategies before committing.

Visual Comparison Table