Public key infrastructure (PKI) has become the backbone of digital trust. From securing internal IT systems and cloud workloads to authenticating IoT devices on factory floors, organizations now depend on certificates at every layer of their technology stack. Your PKI does not end with the Certificate Authority (CA). What is then the challenge? The PKI landscape is broader than ever, spanning open-source tools, cloud-native certificate authorities, SaaS platforms, and fully managed enterprise solutions. You can check out our deep-dives on what is Public Key Infrastructure and what is a Certificate Authority to learn the basics.
Choosing the wrong solution can lead to certificate sprawl, unexpected outages, and costly security gaps. This guide walks you through how to evaluate and compare the best PKI solutions so you can find the right platform for your organization’s needs, whether you’re managing only a few hundred or even millions of certificates.
Start with a needs assessment
Before diving into product comparisons, step back and define what your organization actually needs. A structured assessment prevents you from over-investing in features you won’t use or, worse, choosing a solution that can’t grow with you.
Consider these five dimensions:
- In-house expertise.
According to Keyfactor’s State of Machine Identity Management Report, over half of organizations report they lack enough skilled PKI staff. If that sounds familiar, a managed or SaaS-based solution may make more sense than a self-hosted deployment that demands constant attention. - Control preferences.
Do you need full control over your certificate authority hierarchy, or would you prefer a provider to handle operations on your behalf? The answer shapes whether you lean toward self-managed PKI or a fully managed service. - Use cases (current and future).
Consult teams across IT, security, DevOps, and product engineering. A solution that only covers TLS certificates today may fall short when your IoT product line or DevOps pipeline needs certificates at scale tomorrow. - Scale.
Some organizations manage a few thousand certificates. Others handle hundreds of thousands, or even millions. DevOps and IoT use cases in particular drive high-volume issuance that not every solution can support. - Trust and compliance requirements.
Regulated industries (finance, healthcare, government, automotive) often require FIPS-validated cryptographic modules, Common Criteria certification, or compliance with frameworks like SOC 2, FedRAMP, or eIDAS.
One more factor worth considering: your certificate management maturity. There is a significant difference between issuing certificates and managing them throughout their lifecycle. If your organization is still relying on spreadsheets or manual processes, look for a solution that pairs PKI with built-in lifecycle management.
Understanding the PKI landscape
Not all PKI solutions are built the same way. Before you compare products, it helps to understand the six main categories you’ll encounter.
- Software and hardware PKI. Traditional PKI deployed in your own data center, cloud, or manufacturing environment. This offers maximum control but requires skilled staff and infrastructure.
- SaaS PKI and PKI as a Service (PKIaaS). A third party hosts and operates your PKI. You define policies; they handle the infrastructure, patching, and availability.
- Active Directory Certificate Services (AD CS). Bundled with Windows Server, AD CS is common in Windows-heavy environments. However, it becomes less practical in multi-OS, multi-cloud, or hybrid setups.
- Cloud-native certificate authorities. Services like AWS Private CA and Google CA Service offer tight integration within their respective cloud ecosystems. The trade-off: they are typically limited to that single cloud provider.
- Built-in issuers. Secrets managers, service meshes, and container orchestration tools often include basic certificate issuance. These work well for narrow use cases but typically lack governance, auditing, and lifecycle management.
- Public certificate authorities. These issue publicly trusted TLS certificates for websites and public-facing services. They are not designed for internal or private trust use cases.
Each category has strengths, but most organizations with growing certificate needs end up requiring a solution that spans multiple categories or consolidates them under one platform.
What to look for in a PKI solution: the 6 critical elements
Once you understand your needs and the landscape, use these six criteria to evaluate any solution on your shortlist.
Core PKI functionality
At minimum, a PKI solution should handle enrollment, issuance, revocation, and comprehensive audit logging. But think beyond basic CA software. Look for a full PKI platform that supports multi-tenancy, self-service enrollment through a registration authority (RA), flexible validation (CRL and OCSP), a web-based admin interface, and HSM integration via PKCS#11 or REST API.
Avoid monolithic solutions that require a separate server for every new CA. That approach drives up infrastructure costs and does not scale.
Flexibility and deployment models
The best PKI solutions offer multiple deployment options: containers, virtual appliances, hardware appliances, cloud-hosted, SaaS, and fully managed. Modular architecture matters too. You should be able to deploy root, intermediate and issuing CAs, registration authorities, and validation authorities independently to match your security and availability requirements.
Quantum readiness is another factor to evaluate now. Look for solutions that already support NIST-standardized post-quantum cryptography (PQC) algorithms. And pay attention to pricing transparency; hidden per-certificate or per-CA fees can make a solution far more expensive than it first appears.
Extensibility and protocol support
Standard protocol support is non-negotiable: Starting with X.509 and at least one certificate revocation mechanism (CRL, OCSP) is an absolute must. Also ACME, EST, CMP, CMS, and SCEP should all be included out of the box. Windows auto-enrollment, Microsoft Intune integration, a REST API for custom workflows, SSH certificate support, and CI/CD integrations (cert-manager, secrets managers) round out a mature solution.
Be cautious of vendors that charge extra licensing fees for standard protocols. Protocol support should be included, not sold as an add-on.
Scalability and high availability
Your PKI needs to provision certificates in minutes, not days. Look for horizontal scalability, active-active clustering for CA and revocation services, multi-cloud availability, and built-in disaster recovery. Avoid architectures that force you to stand up additional servers every time you create a new CA.
Certificate lifecycle management
Issuing certificates is only half the equation. Managing them across their full lifecycle (discovery, inventory, renewal, provisioning, and revocation) is where most organizations struggle. The best PKI solutions include or integrate tightly with CA-agnostic certificate lifecycle management (CLM).
Key capabilities to look for include automated discovery and inventory across CAs, self-service portals with delegated ownership, full lifecycle automation, crypto-agility for bulk revocation or CA migration, and integration with enterprise systems like ITSM, PAM, and SIEM.
Vendor compliance, security, and services
For enterprise deployments, vendor certifications matter. FIPS and Common Criteria certifications validate cryptographic integrity. Regular third-party audits (SOC 2 Type II, FedRAMP, ISO 27001) confirm operational security. Ask about software supply chain transparency (SBOM publication) and, for SaaS providers, verify secure facilities and 24/7 global support.
The best open-source PKI solutions
Open-source PKI tools offer a cost-effective entry point, especially for teams with strong technical skills.
EJBCA Community Edition
EJBCA is a Java-based PKI platform that provides CA, RA, and OCSP functionality with support for X.509 and SSH certificates. It handles CMP, SCEP, and REST API protocols, making it one of the most feature-rich open-source options available. Originally developed by PrimeKey (now part of Keyfactor), EJBCA is the most widely adopted open-source PKI CA in production environments. It is available via Docker Hub for easy deployment and offers a clear upgrade path to EJBCA Enterprise for organizations that outgrow the community edition.
Dogtag Certificate System
Dogtag supports X.509 certificate issuance, CRL generation, and protocols including ACME, SCEP, and REST API. It includes a web-based management interface for certificate operations. One limitation: Dogtag requires an LDAP directory and does not support relational databases, which can add complexity to your infrastructure.
OpenXPKI
Built on Perl and OpenSSL, OpenXPKI provides a browser-compatible web GUI along with SCEP and EST support. It is a solid option for teams already comfortable with Perl-based tooling, though its protocol support is more limited compared to EJBCA or Dogtag.
step-ca
step-ca takes a CLI-first approach and is designed for cloud-native and DevOps environments. It supports X.509 and SSH certificates with ACME and SCEP protocols, and it integrates well with Kubernetes, Nebula, and Envoy. step-ca is a strong fit for teams building in containers and microservices, but it requires significant PKI expertise and relies on JSON-based configuration.
How to choose between open-source PKI tools
When evaluating open-source options, focus on five criteria:
- Ease of use. Does the tool offer a GUI, or is it CLI-only? How steep is the learning curve for your team?
- Flexibility and extensibility. Can it support the protocols and certificate types your use cases require?
- Documentation and community. Active communities and thorough documentation make troubleshooting and adoption much smoother.
- Maintenance and active development. Is the project under active development? Regular updates signal long-term viability.
- Enterprise upgrade path. If you outgrow open-source, can you upgrade to a supported enterprise version without rebuilding from scratch?
Top enterprise and managed PKI platforms
For organizations that need production-grade reliability, compliance certifications, and vendor support, enterprise PKI platforms are the standard choice.
Keyfactor EJBCA Enterprise
Keyfactor was named the overall leader in the ABI Research’s 2025 Enterprise PKI Vendors competitive assessment, with both the Top Innovator (94.4) and Top Implementer (95.6) designations. This recognition reflects the platform’s breadth across deployment models, protocol support, and lifecycle management capabilities.
EJBCA Enterprise is available in five deployment models: PKIaaS (fully managed), EJBCA SaaS (hosted on AWS), EJBCA Cloud (available on AWS and Azure marketplaces), Software Appliance, and Hardware Appliance with a built-in HSM. This range of options means organizations can start with a SaaS deployment and migrate to on-premises or hybrid as requirements evolve.
The platform includes the Bouncy Castle cryptographic library (maintained in-house by Keyfactor), ensuring deep control over cryptographic operations and faster adoption of post-quantum algorithms. Compliance certifications include SOC 2, SOC 3, ISO 27001, Common Criteria, and CSfC (Commercial Solutions for Classified).
Other leading vendors
ABI Research’s 2025 assessment also recognized several other vendors in the enterprise PKI space:
- DigiCert is well established in public CA and TLS certificate management with broad enterprise integrations.
- Entrust offers PKI as part of a broader identity and security portfolio spanning digital signing, verification, and secure issuance.
- Sectigo focuses on automated certificate lifecycle management with public and private CA services.
- AppViewX takes a CLM-first approach with orchestration across multi-CA environments.
- CyberArk has expanded from privileged access management into machine identity security and certificate-based authentication.
- GlobalSign specializes in high-volume certificate issuance for IoT and enterprise use cases with its Atlas managed PKI platform.
Each vendor brings different strengths. Review the full ABI Research 2025 report for a detailed competitive comparison.
PKI for IoT device certificates
IoT represents one of the fastest-growing use cases for PKI, and it comes with requirements that differ significantly from traditional enterprise IT.
Why IoT PKI is different from enterprise IT PKI
In enterprise IT, certificates are provisioned to servers, endpoints, or users managed through standard tools. IoT changes that equation:
- Manufacturing-stage provisioning.
Certificates are embedded during manufacturing, not after deployment. - Long device lifespans.
Devices may operate for 10 to 20 years or more, far exceeding typical certificate validity periods. - Headless management.
Devices lack a user interface, so enrollment and renewal must happen automatically. - Private trust.
Most IoT deployments use private CAs, requiring organizations to build and manage their own trust hierarchies.
What to look for in a PKI solution for IoT
When evaluating PKI for IoT, prioritize these capabilities:
- Scalability to millions (or billions) of devices.
IoT deployments can grow rapidly. Your PKI must handle high-volume issuance without performance degradation. - Lightweight protocols.
Standard enrollment protocols may be too heavy for constrained devices. Look for support for EST over CoAP and CMPv2, which are designed for low-power, low-bandwidth environments. - Manufacturing workflow integration.
The PKI solution should fit into your existing production line processes, including support for certificate pre-provisioning and secure key injection. - Factory floor RA deployment.
Registration authorities deployed at manufacturing sites enable local, high-speed certificate issuance without depending on a remote CA for every device. - Industry standard support.
Depending on your vertical, look for support for C-ITS (automotive), Matter (smart home), OPC UA (industrial), or ETSI/3GPP (telecom) standards.
How Keyfactor can help
Keyfactor brings together PKI and certificate lifecycle management on a single platform, combining EJBCA (certificate authority operations) with Keyfactor Command (CA-agnostic lifecycle management). As the overall leader in ABI Research’s 2025 Enterprise PKI Vendors assessment, Keyfactor delivers:
- Deploy anywhere flexibility.
Five deployment models (PKIaaS, SaaS, Cloud, Software Appliance, Hardware Appliance) let you choose the approach that matches your security posture, compliance requirements, and operational preferences. - Scale without limits.
Whether you manage thousands of enterprise certificates or billions of IoT device identities, the platform scales horizontally to meet demand. - Deep PKI expertise.
With over 20 years of experience in PKI, Keyfactor provides the specialized knowledge that general-purpose security vendors often lack. - Comprehensive compliance.
Common Criteria, CSfC, SOC 2 Type II, ETSI/eIDAS, and WebTrust certifications give you confidence in the platform’s security and operational integrity.
As Jason Slack, Director of Engineering at Truepic, put it: ““PKI is an absolute foundational piece to what we’re building. Without EJBCA, we couldn’t have what we have. It is a key pillar of the future of our products.”
Got PKI solutions questions? We’ve got answers.
What is the best PKI solution for enterprise environments?
The best PKI solution for enterprise environments is one that combines robust CA functionality with certificate lifecycle management, multiple deployment options, and strong compliance certifications. According to ABI Research’s 2025 Enterprise PKI Vendors assessment, Keyfactor EJBCA Enterprise was named the overall leader for its breadth of capabilities and deployment flexibility.
Are open-source PKI solutions secure enough for production use?
Yes, open-source PKI solutions like EJBCA Community Edition are used in production environments worldwide. The key considerations are whether your team has the expertise to deploy and maintain them, and whether the project is actively maintained with regular security updates. For organizations that need vendor support, SLAs, and compliance certifications, an enterprise upgrade is usually the better long-term choice.
What is the difference between open-source and enterprise PKI?
Open-source PKI provides core certificate authority functionality at no licensing cost, but typically lacks features like high availability clustering, advanced protocol support, vendor-backed SLAs, and compliance certifications. Enterprise PKI platforms add these capabilities along with professional support, managed deployment options, and tighter integration with lifecycle management tools.
Which PKI solution is best for IoT device certificates?
The best PKI solution for IoT supports scalable issuance (millions to billions of certificates), lightweight enrollment protocols like EST over CoAP and CMPv2, and integration with manufacturing workflows. It should also support long certificate lifespans and private trust models. Keyfactor EJBCA is purpose-built for these requirements across automotive, industrial, telecom, and smart device verticals.
Can I use multiple PKI solutions together?
Many organizations do run multiple CAs, especially during migration or in multi-cloud environments. The key is having a certificate lifecycle management layer that provides CA-agnostic visibility and automation across all your PKI deployments. This prevents blind spots and ensures consistent policy enforcement regardless of which CA issued a given certificate.
What should I look for when evaluating PKI vendors?
Focus on six areas: core PKI functionality, deployment flexibility, protocol support and extensibility, scalability and high availability, certificate lifecycle management capabilities, and vendor compliance and security certifications. Also evaluate the vendor’s track record, community presence, and ability to support your specific use cases.
How does PKI as a Service (PKIaaS) compare to self-managed PKI?
PKIaaS shifts the operational burden to the provider, who handles infrastructure, patching, availability, and security. You retain control over policies and certificate hierarchies. Self-managed PKI gives you full control but requires in-house expertise and infrastructure investment. PKIaaS is often the better choice for organizations that lack dedicated PKI staff or want to reduce operational overhead.
Do I need quantum-ready PKI now?
While quantum computers capable of breaking current cryptography are still years away, the transition to quantum-safe cryptography will take time. Starting now with a PKI solution that supports NIST-standardized post-quantum algorithms ensures your organization can test and prepare without disruption. A crypto-agile PKI platform makes the eventual migration far smoother than a reactive approach.
