secrets-manager
(do not recommend it to use, but can be useful in some cases)
https://github.com/tuenti/secrets-manager

SMI istio adapter
https://github.com/servicemeshinterface/smi-adapter-istio

кресла!
https://github.com/ukrops/newbie/blob/master/README.md

cloudoptimizer
https://cloudoptimizer.io/

Chaos Mesh
Chaos Mesh is a Cloud Native Computing Foundation (CNCF) hosted project. It is a cloud-native Chaos Engineering platform that orchestrates chaos on Kubernetes environments.

https://github.com/chaos-mesh/chaos-mesh

Good replacement for argo-rollouts
https://flagger.app/

extremely useful tool which allow u to keep cluster clean

Popeye - A Kubernetes Cluster Sanitizer
https://github.com/derailed/popeye

Free Kubernetes

list of free saas k8s

https://github.com/learnk8s/free-kubernetes

vals is a tool for managing configuration values and secrets.
https://github.com/variantdev/vals

SLO,SLA,SLI

https://ervinbarta.com/2021/10/19/slo-alerting-for-mortals/
https://habr.com/ru/company/nixys/blog/595259/

#SRE

System Design Examples

Designing WhatsApp - http://highscalability.com/blog/2022/1/3/designing-whatsapp.html
Designing Uber - http://highscalability.com/blog/2022/1/25/designing-uber.html
Designing Tinder - http://highscalability.com/blog/2022/1/17/designing-tinder.html
Designing Instagram - http://highscalability.com/blog/2022/1/11/designing-instagram.html
Designing Netflix - http://highscalability.com/blog/2021/12/13/designing-netflix.html