usql - Universal command-line interface for SQL databases
Observable - Interactive code examples/posts
Jugglingdb - Multi-database ORM for nodejs: redis, mongodb, mysql, sqlite3, postgresql, arango, in-memory... - 1602/jugglingdb
nbviewer.org - Rackspace server host Jupyter Notebooks from your github repo
Rollbar - Rollbar collects errors that happen in your application, notifies you, and analyzes them so you can debug and fix them. Ruby, Python, PHP, Node.js, JavaScript, and Flash libraries available.
Jupyter - Project Jupyter exists to develop open-source software, open-standards, and services for interactive computing across dozens of programming languages. Ready to get started? Try it in your browser Install the Notebook.