I would like to generate a Certificate Signing Request (CSR) and add additional custom information in it.

The standard CSR fields are common name, country, organization, organizational unit, etc.

Is there a field like "note" or something similar that can let me add custom information?

I suppose this is a common problem. What is the standard way to do this?

  • What kind of custom information? You can add arbitrary X.509 extensions to a CSR, but those are all meant for very specific information. If you're looking for a kind of free-form text field, it might make more sense to send this out-of-band. Also, who is supposed to process the CSR? If it's a professional CA, they decide what you can and cannot put into a CSR.
    – Ja1024
    Commented May 25, 2023 at 9:38
  • You can add custom fields to a CSR by adding these in a config file, then use the -config option with openssl req to create a CSR containing these fields. Widely trusted CA's like Verisign, Let's Encrypt, GeoTrust etc., will probably not include these fields in the signed cert, as @Ja1024 mentioned, but if you self-sign or run your own CA, then these fields will end up in the signed certificate. See stackoverflow.com/questions/36007663/… for more info.
    – mti2935
    Commented May 25, 2023 at 11:08

1 Answer 1


You are not mentioning the platform that you are using and the application used to generate the CSRs.

If you are using the Windows Certificate Manager to create a custom CSR, you cannot change the standard fields of "Subject name". However, you can use any custom "Alternative name" you like by choosing "Other name" under the "Type" drop-down list. But, you will need an Object Identifier (OID) to do that. You can register or get a random OID and name it however you want. The OID is put in the "Object ID" field of the custom CSR and you put whatever you want in the "Value" field. Basically, the OID is a structured number field that corresponds to a name and/or description, as defined by the registrant. As a word of advice, I would suggest AGAINST using your own records (fields) in Subject Alternative Name (Alternative name). I can assure you that there already exist many records/fields to cover most, if not all, use cases, already; you just have to search for them, try "x.500 subject name fields" or something similar.

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