The KUbernetes Test TooL (KUTTL) is a toolkit that makes it easy to test Kubernetes Operators, just using YAML.

It provides a way to inject an operator (subject under test) during the TestSuite setup and allows tests to be standard YAML files. Test assertions are often partial YAML documents which assert the state defined is true.

It is also possible to have KUTTL automate the setup of a cluster.

Debugger for Sed: demystify and debug your sed scripts, from comfort of your terminal. 

Falcon is a free, open-source SQL editor with inline data visualization. It currently supports connecting to RedShift, MySQL, PostgreSQL, IBM DB2, Impala, MS SQL, Oracle, SQLite and more.

xlskubectl integrates Google Spreadsheet with Kubernetes.
You can finally administer your cluster from the same spreadsheet that you use to track your expenses.

Kuberhealthy is an operator for running synthetic checks. By creating a custom resource (a khcheck) in your cluster, you can easily enable various synthetic test containers. Kuberhealthy does all the work of scheduling your checks on an interval you specify (like a CronJob), ensuring they run properly within an alotted timeout, maintaining the current up/down state with durability, and producing metrics. There are lots of useful checks already available to ensure the core functionality of Kubernetes, but checks can be used to test anything you like.