In case there are questions, concerns, comments or ideas (be they positive or negative, or something you might think I could improve or learn from), do please feel free to contact me through any of the following methods (email prefered). I am always happy to discuss things so that things can become better.

I keep work, projects/hobby and private strictly separated and thus communications which try to come through the wrong channel are silently rejected. Thus please use the proper channels.


QR Code of Jeroen Massar's vCard
Jeroen Massar's vCard

My preferred way of contact is per email at: Jeroen Massar <>.

While I am present on various social networks, email is a much better way to contact me as I do not regularly check social networks.

One can also use the vCard containing my contact details or scan the QR Code on the right.

Like most other people I don't like spam, as such that address is filtered by the excellent SpamAssassin. The policy is set to reject all viruses and spam during SMTP-DATA thus I won't see them but the sender will receive a NDR indicating that it was rejected and the reason why. PGP signing and encrypting your email ensures that the message passes. Don't forget to publish your PGP key in the PGP Keyservers if you want answer though.

Pretty Good Privacy

My PGP keyID is 123421B735578C46 but due to collisions better check the full fingerprint below or use the QR Code to import it to your device. My old keyID was 333E7C23, still active but should not be used anymore.

123421B735578C46 (4096 bit, 2015, active use): 6AC3 85A3 E350 0A2E 07AE 5548 1234 21B7 3557 8C46

333E7C23 (1024 bit, 2003, deprecated): 48E8 2BD4 3B4A 622E 405C 3A35 29AA 2852 333E 7C23

Get my full PGP key from here directly.


Being in the Apple ecosystem means that one can of course reach me also through iMessage. Email is still prefered though, unless it is a really urgent matter.

iMessage Contact Verification Public Key: APKTID_hUabMEJKVj27QGgHOpshvRwtSapfgWyiCd6f2yh0OLRcA

Threema QR
Threema ID


As secure communications platform with non-Apple users I have chosen Threema. From independent audits, it looks like they are doing the right thing, and as they are in Switzerland, I can easily pay them a visit. One can use the QR code on the right to add me. Email is still prefered though, unless it is a really urgent matter.


Typically a customer specific email address will be available for the duration of the project. These addresses I typically do not publish and are only used for the communication inside that project.

Projects & Hobby

Please use the relevant contact methods for each project:

All projects have abuse@ and security@ address for abuse and security related issues along with a /security.txt record providing the details. PGP keys for these addresses are also published on the website, use them where necessary.


Please see AQ: Any old email addresses? for old, and thus unused, contact methods.