The ESP8266 from Espressif was probably the most widely used microcontroller in non-Arduino projects at one time.
It became an instant success when it surfaced in 2014 and initiated the decline of the Arduino dominance at that time.
The ESP8266 was remarkably affordable and outperformed Arduino boards in almost every aspect at a fraction of the cost.
- Memory: with 4MB flash memory (typical), the ESP8266 ended the notoriously scarce memory that Arduino users fought with back then
- WiFi: built-in WiFi support opened the doors for home automation and web interfaces while Arduino users were stuck with boring and wired terminal communication.
- Size: the ESP8266 had a significantly smaller footprint, enabling users to build slick portable devices.
- Cost: ESP8266 was available at a fraction of the price compared to Arduino boards, and even cheaper Clones were available thanks to the open-source board designs.
Today, more than a decade after its release, ESP8266 is retired for good, though, and there is no reason anymore to buy new ESP8266 boards.
While you can certainly use up your stocked ESP8266 for small projects, consider the ESP32-S2 Mini (if you want to use the same form factor and maintain compatibility with shield boards), or ESP32-C3 SuperMini (for an extremely affordable board with a super small form factor).
Overview
The ESP8266 was the first Espressif microcontroller with broad success in the DIY community, primarily because of its affordability and built-in WiFi.
Many users moved from Arduino to ESP8266, and in the end, generic ESP8266 boards were available for under €1.00.
Today, do not buy ESP8266 anymore:
- Design Flaws: Most ESP8266 development boards—at least affordable generic ones—come with underrated voltage regulators: unexpected brown-outs and reboots occur when external components like sensors or displays exceed the voltage regulator’s maximum current.
- Unsafe: ESP8266 is single-core, and compared to its successors, relatively slow. It cannot use secure https connections when connecting to WiFi and the Internet. Instead, it uses the unencrypted old http standard.
- Expensive: Today, the much more capable successors cost just as much as ESP8266 (sometimes even less), which makes ESP8266 appear expensive in comparison. You get much less bang for the buck.
- Features: ESP8266 has less of everything when compared to its successors: fewer GPIOs, less speed, less memory, less safety, less reliability, etc.
Key Specs
| Item | Value | Comment |
|---|---|---|
| GPIO | 17 | Actually available pins depend on breakout board |
| SPI | 1 | For fast peripherals |
| I2C | 1 | Software implementation, for slow peripherals |
| UART | 1 | Serial communications, external serial-to-USB chip required for USB |
| Flash Memory | 4MB (typical) | Boards range from 512K to 16MB |
UART: CH9102, CP210x, CH340
ESP8266 do not natively support USB, so they need a dedicated UART chip, plus you may need the appropriate driver installed on your PC.
Here is an overview of popular chips and whether they are natively supported on your PC operating system:
| Item | CH210x | CP9102 | CH340 | Remarks |
|---|---|---|---|---|
| OS | all | all | Windows | Other OS may need manual driver install |
| Price | medium | medium | low | |
| Speed Mbps | 12 | 4 | 2 |
The CP9102 is a relatively unknown variant that is pin-compatible with the CH210x. It is slower but still twice as fast as the CH340.
There are other chip types such as FT232RL, PL2303, MCP2221, and MAX3421 that are even less commonly found.
D1 Mini
The D1 Mini was probably the most popular ESP8266 development board:
It was affordable, compact and flat, came with WiFi capabilities, had sufficient memory (typically 4MB), provided sufficient GPIO pins for most projects (9 of which 5 were freely usable), had one ADC, and supported SPI and I2C interfaces.
It used the Espressif ESP8266EX chip, basically the only ESP8266 variant widely found.
The D1 Mini board was so popular that a whole ecosystem of pin- and size-compatible “shield boards” became available (i.e. power supplies, battery boards, sensor extensions, etc.).
Today, the ESP32-S2 Mini has preserved the D1 Mini form factor and is pin-compatible, so you can continue to use the shield boards that were originally designed for the ESP8266 D1 Mini.
ESP8266 Pro
The Pro version of ESP8266 never gained traction. Its most visible “advantage” was a ceramic antenna instead of the simple PCB antenna and more memory: most ESP8266 Pro came with 16MB instead of 4MB memory (some just 8MB or even 4MB).
This board used an unshielded version of ESP8266 that has no FCC ID (may violate EMR standards and FCC regulations). It typically used the same insufficient voltage regulator that was found on other cheap ESP8266 clones.
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(content created Mar 23, 2024 - last updated Aug 03, 2025)