DigiCert Open Source is a collection of three open-source tools for PKI, certificate management, and IoT device security: **TrustCore SDK** A cryptographic library for IoT and embedded devices, providing secure communications, trusted device identity, and lifecycle protection in constrained environments. It supports broad protocols and FIPS-compliant capabilities. Released under AGPLv3, it has been used in production for over 15 years. Available at github.com/digicert/trustcore. **DCV Library** An open-source domain control validation (DCV) library covering all non-ACME domain validation (DV) methods as defined by the CA/Browser Forum Baseline Requirements. It supports email, DNS record verification, and HTTP/HTTPS-based validation methods. The library is implemented in Java and containerized, with multi-perspective validation support in progress. Released under the MIT license. Available at github.com/digicert/domain-control-validation. **pkilint (Certificate Linter)** An open-source PKI linting framework for analyzing digital certificates, CRLs, and OCSP responses for errors and compliance issues. Built on an ASN.1 parser, it supports linting against multiple standards and trust frameworks, including CA/B Forum Baseline Requirements. It can be used during certificate issuance or to audit existing certificate directories. A companion tool, SMBR-Cert-Factory, is also available for generating S/MIME Baseline Requirements-compliant test certificates. Available at github.com/digicert/pkilint.