Alternative to GnuPG/OpenPGP - including encryption at rest, file and backup

alt-to-gnupg.md

List of GnuPG/OpenPGP replacement (not OpenPGP compatible)

• https://github.com/wbl/cpgb CPGB is the Curve Privacy Guard B, a secure replacement for GPG using ECC. (Status: Dead? last-update:2011)
• https://github.com/carlos8f/salty Alternative public key encryption using NaCl. (Status: Dead? last-update: 2016)
• https://github.com/TotalTechGeek/DiscreteCrypt This tool is an alternative to software like PGP, with a focus on Discrete Log Cryptography. The algorithm is currently in v2.2.5. (Status: Active)
• https://saltpack.org/ a modern crypto messaging format (Status: Active)
• https://github.com/stealth/opmsg opmsg is a replacement for gpg which can encrypt/sign/verify your mails or create/verify detached signatures of local files. (Status: Active)

List of GnuPG replacement (OpenPGP compatible)

• https://github.com/das-labor/neopg - https://neopg.io/ " The multiversal cryptoengine!" (Status: Active (Alpha))
• https://sequoia-pgp.org - OpenPGP implementation in Rust

Partially covering replacement - Signature only

• https://github.com/jedisct1/minisign - A dead simple tool to sign files and verify digital signatures. (Status: Active)

NeoPG looks dead - also the domain now owned by something very unrelated to PGP completely ;)

AGE ("actually good encryption", bold name) is another standard. It has two main implementations, the reference in golang (https://github.com/FiloSottile/age) and the other one in rust (https://github.com/str4d/rage).

https://sts10.github.io/2021/09/06/exploring-age-1-point-0.html looks like a good primer.