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Swifitch is ESP8266 based relay board that could be used to turn any light or any wall socket into smart one!


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What is it?

ESP8266 based WiFi enabled relay board, that will let you easily turn any light or any plug to SMART one. Easily control using HomeKit (other HW needed) or using any MQTT based SmartHome application. Or if you are skilled developer, write any code you want.

What can it do?

Main purpose is to turn things ON or OFF. But it can do lot more than that, swifitch is equiped with header to connect another 4 digital devices and 1 analog. These could be sensors etc.

If you need, by sacrificing one of the data pins, you can get 5V for your 5V sensors.

⛔ Be aware that swifitch's pins are not 5V tolerant and cannot accept 5V on any of the pins provided, and it will damage the ESP.

There are also two jumpers. One is for enabling deep sleep and the other is to put ESP into flash mode when you use conventional USB2UART programmer. We have reused one NodeMCU to make a lot more convenient programmer out of it, because it handles resets and flash mode boot automatically. Details will follow.

What is expected cost?

We have designed swifitch to be both cheap and safe. So it is not ultra cheap but not expensive too. Our cost calculations has stoped at $8! Not bad, what you think?

How does it look like?

Definitely beautiful!!

How big is it?

Actually very small, you should be able to fit it almost anywhere without any hassle. But I know, numbers tell it all, so here it is.

Width Height Depth Weight W/O BOX Weight W/ BOX
42mm / 1.65" 60.5mm / 2.36" 19.6mm / 0.77" ~42g / ~1.48oz ~72g / ~2.54oz

Is it safe?

We have designed few safety features in swifitch. Most important are fuses on mains input. There is one overcurrent fuse and one overvoltage fuse (surge protection), and more importantly temperature fuse that will disconnect swifitch from mains input when temperature raises above 100°C. There should be another few safeties in HLK-PM01 but we didn't want to depend on it's quality.

OK I'm sold! What do I need to build it?


Preview Part Buy
4.7μF 0805
100nF 0805
10nF 0805
47μF ⌀6.3x5mm
47nF X2


Preview Part Buy
10kΩ 0805
1.5kΩ 0805
2.2kΩ 0805
47kΩ 0805
160Ω 1206

Power and Controls

Preview Part Buy
PROFFUSE TZ-P100/2 100°C or similar
Hi-Link HLK-PM01 AC-DC 5V/3W
SRD-05VDC-SL-C Relay

Other SMD Parts

Preview Part Buy
MCP1825T-3302E/DC Voltage Regulator
Ferrite Bead 600Ω 100MHz 0805
Any 0805 LED diode


Preview Part Buy
Headers 1x2 2.54mm pitch
Headers 2x5 2.54mm pitch
Terminal 2P and 3P, 5.08mm pitch rounded lead

The rest

Preview Part Buy

Most of it could be purchased on AliExpress or eBay for what we call "no money", some parts are safer to get from your local trusted electricians shop (fuse and relay if you do not want chinese).

Most AliExpress links in table above are tested and trusted sellers, but we do not give any guarantees. is good source for EU citizens and especially guys in Czech Republic.

Farnell should be OK for all over world.

SeeedStudio Fusion PCB

How to order PCBs

First grab gerber files ZIP and upload it to SeeedStudio Fusion PCB then follow instructions below.

We have created sreenshots from ordering process so you can recreate the process in same manner. Decide how many pieces you want and get started. Keep in mind that each board are actually two swifitches ;). That makes it even cheaper.

Gerber files preview:

After you build it

OK DONE! What's next?

Now you need to flash some software to it. Either use conventional CP2102 USB2UART programmer or build your own as we did from NodeMCU, it is definitely best option you have.

This image tell you all you need to know but basically this is the list of steps:

  • Desolder ESP8266 from NodeMCU (Heatgun baby!! But carefully you can use it for swifitch then.)
  • Solder colored wires to the contacts according to image below
  • Insert these wires to 2x5, 2.54mm pitch connector
  • Connect to swifitch and flash firmware

We have created software for you to get started quicky so go to it's own repository.


It should be safe, but we do not recommend it!


Swifitch default software

If you went with our software you are good to go, just follow the README in the repository.

Custom software

Just few things you need to know if you develop your own software.

  • Relay is controled by D1 or GPIO5 PIN
  • Built in LED is controled by D6 or GPIO12 PIN


3D Printed

If you have access to 3D printer, have a look at our original swifitch box.

If you wish to design your own box and you use Fusion 360, here is 3D model of Swifitch.

Use ABS plastic filament as this device is using mains voltage and ABS is safer for such devices.


Purchased ABS box

We have fitted swifitch to box that can be purchased from various electrical shops. May not be available in all countries thought.

Soldering cheatsheet

Back side

Start with SMD parts on the BACK side.


Slot Part
C1 4.7μF
C3 4.7μF
C5 4.7μF
C6 4.7μF
C4 100nF
C7 100nF
C8 10nF


Slot Part
R3 10kΩ
R4 10kΩ
R5 10kΩ
R6 10kΩ
R7 10kΩ
R8 2.2kΩ
R9 47kΩ
R10 160Ω
R11 160Ω

The rest

Slot Part
FB1 FB 600Ω 100MHz
D1 BAS86
T1 BC817
WiFi1 ESP8266-12(E/F/S)

Front side

Front side contains mostly THT parts, but start with SMD parts that would be harder to solder when you finish all bigger parts.


Slot Part
R1 470Ω < Rled < 2kΩ (depends on LED1)
LED1 Choose color you like
V1 Voltage Regulator


Slot Part
F2 100°C fuse
R2 S10K275
F1 MST250/0.5A
C10 47nF
C2 47μF
C9 47μF
SB1 Optionaly enable D5 or 5V
JP1 1x2 header
JP2 1x2 header
J3 2x5 header
RE1 Relay
J1 2P terminal
J2 3P terminal

🎉 DONE 🎉


  • PCB design, electronics ideas, parts selection - Miroslav Batěk
  • SW, Git Repo, design, 3D printed enclosure - Martin Doubek


Yellow Couch

Czech - with English subtitles

What's next?

If you liked swifitch and want to submerge deeper into IoT we will reference some other projects here.

IoT platforms and enablers.



Swifitch is ESP8266 based relay board that could be used to turn any light or any wall socket into smart one!








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