EMBO - Scope for only $6. Embedded instruments: Oscilloscope, Logic Analyzer, Voltmeter, Counter, PWM and Signal Generator on STM32 MCUs (F1, F3, L4, G4 ....). PC app for Windows, Ubuntu and macOS. Firmware is in C, PC GUI app is in C++ Qt 5.
TI MSP430 Bootloader (BSL) .NET Cross-Platform Toolchain & Firmware Tools. The cheapest way to flash MSP430, with FTDI/Serial/UART converters. Intel-HEX, TI-TXT, ELF and SREC firmware format support, can also convert, combine, hex-edit..
NTP Client (Windows DLL/LIB + Console App + CVI GUI App) - small and accurate NTP client, easily integrable into any app