There are 2 repositories under attiny topic.
Arduino core for ATtiny 1634, 828, x313, x4, x41, x5, x61, x7 and x8
Cooperative multitasking for Arduino, ESPx, STM32, nRF and other microcontrollers
Передача показаний воды по Wi-Fi. Watermeter Wi-Fi transmitter.
Arduino core for the tinyAVR 0/1/2-series - Ones's digit 2,4,5,7 (pincount, 8,14,20,24), tens digit 0, 1, or 2 (featureset), preceded by flash in kb. Library maintainers: porting help available!
Library for an ATTiny85 to use an SSD1306 powered, double buffered, 128x32 pixel OLED, over I2C
Battery powered door and window sensor with ultra low standby power. Arduino, ESP-12, Reed switch, ATtiny, LDO
A Streamlined IDE for Coding and Programming the ATtiny10 and other ATTiny Devices
Collection of cartridges, adapters and replacements for the Commodore C64
Arduino hardware SPI library for ATtiny44/84, 45/85, 461/861, 2313/4313.
Minimal I2C master routines for all AVR microcontrollers.
Fast Graphics Library for Attiny85 and SSD1306 over I2c
Uninterruptible Power Supply
Collection of AVR Programmers and Accessories
Small FM Radio with RDS and OLED
RS485 ModBus tiny multi-sensor module
I²C OLED on an ATtiny10/13/202
T12 Quick Heating Soldering Station
An Arduino library for the 16-bit, 4 channel ADS1115 ADC. Convenient to use. All features of the ADS1115 are implemented, including alert functions.
IR Remote Control
FM Radio with RDS
A resource-conscious neural network implementation for MCUs
C++ platform to build Arduino and AVR projects. Rationale is size and speed optimization.
OSC Calibrator and High-Voltage Fuse Resetter for 8-Pin ATtinys
2.5kV Isolator for the USB Power Rail
Power Supply Analyzer with USB Interface
Simple USB Power Tester
An Arduino-based debugWIRE hardware-debugger