But one of the problems I faced was my dependence on Google's Contacts service which kept all of my contacts for me stored on my Android device. I wanted to move away from this as well. But I also have an animosity towards having email on my phone.
So without installing Protonmail on my phone, how could I take my contacts stored on Protonmail and put them on my phone?
Well one obvious way was to export Protonmail's contacts to a VCF file and import that onto my phone. Unfortunately, Protonmail's VCF file was using version 4.0, while my phone (Android version 8) was still stuck on VCF version 2.1. And I wasn't the only one with issues with converting VCF file format versions:
But all of the tools I found went from version 2.1 to something newer. I couldn't find any converters from a newer version down to an older version.
Protonmail (at the time of this post) uses version 4.0. So I wrote a converter from version 4.0 (Protonmail) to version 2.1 (what Android still uses).
You can find my converter here: https://github.com/evandowning/vcf-converter
So everytime my Protonmail contacts get updated, I export them to a VCF file, convert it to version 2.1, and transfer it to my Android device to be imported locally.