LTspice - LTspice® is a high performance SPICE simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits.
Ghostnote - Add notes to anything.
Large - On-demand Slack bot that can get you anything for the office
Somnote - More often than not, note-taking is a pressing, off the cuff movement that requests a quick and productive approach.
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
Box Notes - Box Notes: take meeting notes, share status updates and plan projects together instantly. Online, across devices.