Summary
Unless you’re blinking your ESP32’s onboard LED, most projects involving the board have a tendency to start with a simple idea, and before you know it, you’ve got a shopping cart full of components. Thankfully, you don’t need to build a circuit from scratch to make something useful out of your ESP32. With just a breadboard, a few extra components, and the right firmware, there are tons of projects that would never require you to touch a soldering iron. Whether you want a smarter home or a handy desk gadget, there are tons of projects you can invest in without having to fiddle with molten metal. An outage alarm that doesn’t wake the whole house One RGB LED, one OLED, and four wires. No buzzer at 3 a.m. You only really need a Wi-Fi-capable microcontroller and an LED or buzzer if you need an audio cue for what is an otherwise pretty useful desk gadget. The average ESP32 is more than capable for this, so there’s no risk of choosing the wrong ESP32 board. However, I ended up choosing my ESP32-S3, the beefier sibling of the classic ESP32, which comes with a built-in RGB LED, as I didn’t want a buzzer going off in the middle of the night if my internet goes down. The RGB LED helps because I can use the same (and rather bright) LED to indicate different states. A flashing blue light means the board is connecting to my Wi-Fi, a solid green light means the internet is working, a solid red light means it’s offline, and a blinking red light means the Wi-Fi network itself isn’t available. I also threw in a 1.3-inch SH1106 OLED display to show information like the SSID, local IP address, Wi-Fi signal strength, and a live uptime or outage duration counter depending on the situation. Thanks to the RGB LED on my ESP32-S3 board, there are only four connections you need to make. The SH1106 connects over I2C through two GPIO pins for SDA and SCL, with power going to the ESP32’s 3.3v pin and ground to the board’s ground connection. Your Claude Code quota deserves a physical gauge A small OLED, a DHT22, and one button instead of clicking a tiny icon If you’re working with larger codebases or monorepos, Claude Code’s rather limited context window and usage limits can be a problem. I solved Claude Code’s memory problem with a Postgres database, but constantly clicking a tiny icon to see how much of my usage quota is left was frustrating. I decided to fix this by creating a small dedicated dashboard that showed my usage limits, so instead of clicking around or typing in commands, all it takes is a glance to see where I’m at. I also decided to add a temperature sensor so the dashboard can also show my office’s ambient temperature and humidity, which I can pipe into my Home Assistant dashboard to set up automations for my air conditioner. It’s a relatively simple build. All you need is an off-the-shelf ESP32, a DHT22 temperature sensor, a generic monocolor OLED screen (I’m using an SH1106 display, but any other display works fine), and a simple push button to cycle through the information on the display. That’s it. A thermostat for rooms that never got a thermostat A C3 Supermini, a DHT22, and an AC that finally listens With a tiny ESP32, a temperature sensor, a screen, and a few buttons, you can create a climate controller for your home that’ll maintain whatever temperature you want across rooms, regardless of whether you’ve got a smart air conditioner or a dumb one. All it takes is a little time. I wanted a device that could control the ACs in my bedroom and office to maintain a specific temperature, as well as provide a quick physical button I could use to control lights without having to fiddle with my phone or Home Assistant on my PC. The part list for this build is about as basic as it gets. First, you need an ESP32. Any variant of the board works, but I chose the ESP32 C3 Supermini for its small form factor because I wanted to make magnetic docks for my office and bedroom that I could dock the device in. A DHT22 provides basic temperature and humidity data that’s used to control both my ACs, which are in turn connected via Tapo smart plugs to the wall. A 1.3-inch SH1106 OLED display shows data, and tactile buttons help navigate the menus and toggle devices. I started creating the climate control logic by adding a Climate Control page to the device, which arms or disarms the main Home Assistant automation and shows a snowflake icon on other pages to indicate the AC’s actual state. The automation holds whichever room is currently selected between 28 and 30 °C using the onboard DHT22 reading, but only while armed, and only for one room at a time. Teach a cheap LED strip to talk to Wi-Fi Three MOSFETs, one ESP32, and no addressable LEDs required It’s easy to use WLED to run addressable LED strips like the WS2812B, SK6812, and similar varieties from your ESP32 with only three hardware connections to make. But even if you’ve got a cheap, non-addressable 12V LED strip, you can turn your ESP32 into a Wi-Fi controller and make it do things commercial solutions like Philips Hue can’t even dream of. The whole build revolves around an ESP32 DevKit V1 board, and three IRLZ44N N-channel MOSFETs — one per channel — powered by the original 12V 1.5A supply. Since cheaper LED strips often run on 12V channels, MOSFETs are important to allow the ESP32’s 3.3V GPIO pins to control their respective channels. Wiring involved connecting the IRLZ44N drain pins to the LED strip’s color channels, source pins to a common ground rail (which the ESP32 connects to as well), and the gate pins to three PWM pins on the ESP32. I kept the ESP32 separate from the 12V used to run the lights, as its onboard AMS1117 voltage regulator would be pushed close to its limit and burn off the extra voltage as heat. USB is safer and simpler in this case, but you can throw in a cheap buck converter to knock that voltage down to 5V and run everything off the same power source. Turn an ESP32 into a passkey you can lose Native USB, open-source firmware, and no WebAuthn stack to write FIDO2 and U2F, the protocols behind hardware passkeys, don’t really need exotic secure silicon to work properly. There’s no TPM2.0 requirement like Microsoft forces on older processors to run Windows. All you need is a microcontroller that can handle USB HID communication and elliptic curve cryptography like ECDSA over NIST P-256. The ESP32-S2 and ESP32-S3 both have native USB-OTG support, which means they can present themselves to a computer exactly like a real USB security key would, no extra USB-to-serial chip required. Open-source firmware projects have already done the hard cryptographic work, so you’re not writing a WebAuthn stack from scratch; you’re just flashing something that already exists. I tested two options before settling on one. The first is Pico Fido2, a project built for the Raspberry Pi Pico and the ESP32-S3. It also happens to be one of the most feature-complete options out there, supporting CTAP 2.1, CTAP 1, OpenPGP smartcard functions, and even YubiKey-style OTP emulation. The second option is esp32_u2f, a more minimal project focused purely on getting U2F and FIDO2 working over a driverless HID interface without the extra smartcard baggage. If you just want passkey login for sites like Google or GitHub, esp32_u2f is the learner build. If you want something closer to a full YubiKey replacement with OpenPGP and OATH TOTP support, Pico Fido2 is the better long-term pick. Pick one project and keep the soldering iron cold Solderless doesn’t mean effortless, but it does mean fewer burnt fingers The best thing about these projects isn’t simply avoiding soldering; it’s getting to spend more time using something you made and less time wondering whether your solder joints are perfect. That said, just because a project is solderless, it doesn’t automatically make it effortless either. Firmware setup, compatible hardware, and sensible security choices still matter. Start with the internet monitor or hardware security key if you want the simplest hardware requirements, or choose a display project for something more visible. Pick one useful job, build around it, and let the finished project earn its place in your life.