Frequently Asked Questions

Short answers to the most common questions. Every answer links to the full guide.

General

What is Circzy?

An electronics lab in your browser for learning Arduino, ESP32, Raspberry Pi Pico and STM32 without hardware. Circzy has three services: the Simulator for learning, Classroom for teachers, and Certification for skills exams and certificates. See Welcome to Circzy.

Is Circzy free?

Yes. The simulator is free forever with every board and part. Pro, Classroom and certification vouchers are paid. See Plans & Payments.

I have never studied electronics. Can I still use it?

Yes, that is exactly who Circzy is built for. Read the Glossary, follow Your First Simulation in Blocks mode, then copy projects from the Gallery.

Do I need to install anything?

No. Circzy runs in the browser on laptops and phones. All you need is a Google account and an internet connection. If you want to run Circzy on your own computer without internet, see Offline Installation.

Do I need internet?

Yes, to sign in, save projects and compile programs. Once a program is compiled, the simulation runs on your own device.

Can I use it on a phone?

Yes. Circzy is designed for touch screens: add parts, connect wires and run the simulation with taps. For large circuits a laptop is more comfortable.

Which languages are available?

English and Indonesian. Use the EN/ID button in the top bar. The choice applies to the whole interface, including blocks, part names and error messages. See Settings & Language.

Account and projects

Where are my projects stored?

When you are signed in, projects are stored in your account and can be opened from any device. Projects are also saved automatically every time you change them. See Accounts, Cloud Projects & Pro.

How do I share a project?

Make the project Public, then click Share to copy its link. Anyone with the link can open and run it. See Saving & Sharing Projects.

What is the difference between Free and Pro?

Pro gives more projects, no compile queue, extra libraries, firmware download and the virtual phone. The full table is in Plans & Payments.

Programming

Blocks or Sketch: which mode should I choose?

Choose Blocks if you are new to programming. Circzy turns your blocks into Arduino C++ code you can read in the sketch.ino tab. Choose Sketch if you already know Arduino code or need a library that has no blocks. A blocks project can be converted to a sketch at any time, but not the other way round. See Block Editor and Sketch Editor.

Can I use any Arduino library?

In Sketch mode, Pro users can search the Library Manager and click Install. Libraries compile exactly as in the Arduino IDE. Libraries for parts Circzy does not simulate still compile but read nothing. See Libraries.

Will code from Circzy work on a real board?

Yes. Circzy compiles with the official board packages through arduino-cli. Pin numbers, libraries and timing work the same as on hardware. Copy the code into the Arduino IDE, or download the firmware (Pro), and upload it to your board.

Why does my program run slower than real time?

A program that loops without pauses makes the emulator execute every instruction, and on a slow device it can run slower than real time. Programs that use delay() run at real speed. See Simulation Limits.

Circuits

Does my LED need a resistor?

The simulator will not burn out an LED, but adding a resistor is a good habit because a real LED without one can be damaged. Circzy draws the circuit exactly as you would build it.

How does the breadboard work?

Place a part on the breadboard and its legs connect to the holes underneath. The five holes in one column are connected, and each power rail is connected along its length. See Breadboards & Power.

Can I change sensor values while the simulation runs?

Yes. Select the sensor and use the sliders in its toolbar (temperature, humidity, distance, light, gas and more). Buttons, switches, potentiometers and keypads work directly on the canvas. See Running the Simulation.

Classroom

Do students have to pay?

No. Only the teacher subscribes. Students sign in with Google and join with the class code. See the Student Guide.

Are Classroom practice questions graded automatically?

Multiple choice is graded automatically. Practice questions are graded by the teacher, who opens and runs each student's circuit from the grading page. See the Teacher Guide.

Certification

Is the Circzy certificate recognized?

A Circzy certificate is a skills certificate issued by Circzy, not a government or BNSP certificate. Its value lies in verifiable proof: every certificate has a unique number and QR code showing the name, track and status. See How Certification Works.

What if I do not pass?

One voucher includes several exam attempts. You can retake after the waiting period, and a free practice exam is available to prepare.

Troubleshooting

I get a message that the compile server cannot be reached.

Check your internet connection and press ▶ again. If it still fails, the server may be busy or under maintenance; try again in a few minutes. See Troubleshooting for more problems and solutions.