DuckDuckGo still supports all of those developer tools:

https://duckduckgo.com/?q=base64+foo

https://duckduckgo.com/?q=ascii+table

https://duckduckgo.com/?q=qr+code+foo

https://duckduckgo.com/?q=color+picker

https://duckduckgo.com/?q=json+formatter

Along with the timer from OP:

https://duckduckgo.com/?q=6+minute+timer