If you are looking for an admin tool, you already have good answers; however, if you need to create certificates from code, here are a few alternatives you can try (full disclosure: I am a developer for these products), Versile Python (Git repos: python 2 , python 3 ), and Versile Java ( Git repo ). They do not fully implement X.509, but enough to create basic certificates, including some of the major certificate extensions.
Versile
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