I build projects with Arduino and Espruino. I've designed dozens of circuit boards for these projects.

I maintain the ATTinyCore, megaTinyCore and DxCore hardware packages for Arduino.

PROTOTYPING BOARD
Strip Board, Protoboard, prototyping board, solderable breadboard - whatever you want to call it - has been a mainstay in electronics prototyping for decades, and hasn't changed much in the interim (not even in production quality, as they're still often single-sided and/or manufactured from low-grade phenolic resin instead of FR4).

My prototyping board creations bring these into the modern era, offering a combination of 0.1" through-hole prototyping areas (consisting of groups of 2, 3 or 4 pins connected together, like solderable breadboard) and pads for common surface mount packages connected to through-holes for easy soldering.

I offer prototyping board between 4" x 4" to less than an inch square in my Mini Protoboard line. Unlike most commercial prototyping board, these boards are made to the same quality standards as real PCBs. Through-holes are plated and the boards are double sided.

These are offered in both generic versions, and ones tailored to specific microcontrollers, like the Tiny84/85, or microcontroller boards, like the Espruino Pico, Arduino Pro Mini, and the wildly popular ESP8266.

ATTINY BREAKOUT BOARDS:
I love the ATtiny lineup, particularly the latest part in the 1-series and 2-series . These have the highly capable modern AVR peripherals also featured on the Dx-series and - in the case of the 2-series, the headline new feature slated for the EA-series, whenever those become available: A new ADC -12 bit, proper differential functionality, programmable gain amplifier, 1024 sample accumulation for oversampling, and more, This is the first "modern" (post-2016) AVR with a fully functional differential ADC with programmable gain. (The Dx requires the analog voltage to be less than VRef - which kind of defeats the whole point of a differential ADC.

OTHER BOARDS:
I also sell a number of other boards to fill gaps in the market, including a breakout board for the popular LoRa/LoRaWAN modules from Microchip (the RN2483 and 2903), which has become one of my top selling items.

I also sell MOSFET drivers and breakout boards for logic level MOSFETs operating at logic levels as low as 1.8v. These are almost invariably SMD parts which are difficult to use without a properly designed breakout board. Azduino offers boards with modern and high performance FETs.

Azduino by Spence Konde's Page SpenceKonde