Viewers:

• jid - json incremental digger, a ui for json files
• jq - a lightweight and flexible command-line JSON processor
• yq - a portable command-line YAML processor
• xmlstarlet - command line XML toolkit

Web services:

• draw.io - free online alternavite to visio

Dev:

• mailbucket.io - mail server for testing

Tools:

• ncdu - cli disk space analyser
• top / htop / glances - process viewers
• fc (shell builtin) - for listing, editing and re-executing commands previously entered into an interactive shell
• fpp - path picker

Others:

• sindresorhus/awesome - a curated list of awesome lists
• pandoc - a universal document converter
• Samat Galimov - tools page

Terms:

• fluent programming style
• idiomatic solution
• speculative optimization (java)