OCPP Simulator & Emulator: Test a CSMS with a Virtual Charger

What is an OCPP simulator?

The Open Charge Point Protocol (OCPP) is how EV chargers talk to the software that manages them — the CSMS (Charging Station Management System, called the Central System in OCPP 1.6). A charger opens a WebSocket to the CSMS, announces itself with a BootNotification, and from then on both sides exchange JSON messages: authorizations, transactions, meter readings, status changes and remote commands.

An OCPP simulator — also called an OCPP emulator or charge point emulator — plays the charger's side of that conversation. Instead of wiring up real hardware, you point a virtual charge point at your CSMS and drive it from a UI. That makes it the fastest way to develop, debug and regression-test OCPP backends, and to reproduce edge cases that are hard to trigger on a physical charger.

What this simulator can do

• Three OCPP versions

  OCPP 1.6J, 2.0.1 and 2.1 over WebSocket, switchable per charger.

• Real charging sessions

  Plug in, authorize, start, stop or auto-charge with live meter values and state of charge.

• Remote commands

  Answers RemoteStart/Stop, Reset, UnlockConnector, TriggerMessage, Get/ChangeConfiguration and around 30 more CSMS requests.

• Many chargers at once

  Open chargers as editor-style tabs, or spawn a whole fleet to load-test your CSMS.

• Edge cases on demand

  Inject hardware faults, drop offline, add response latency or send malformed frames.

• Every message logged

  A live log of each frame with direction and timing, exportable as JSON or CSV.

How to test a CSMS in four steps

1. Open the simulator. It runs entirely in the browser.
2. Open Configuration and enter your CSMS WebSocket URL (for example wss://csms.example.com/ocpp) and the charge point ID your CSMS expects.
3. Choose the OCPP version and select Connect. The simulator sends a BootNotification and starts heartbeats once it is accepted.
4. Plug in, authorize and start a transaction — or wait for your CSMS to send a RemoteStartTransaction — and watch each message in the log.

Testing a CSMS on your own machine? See connecting to ws://localhost.

Who uses it

• CSMS developers building or debugging an OCPP backend.
• QA engineers reproducing charger behaviour, faults and timeouts on demand.
• Charge point operators and integrators checking a platform before real hardware arrives.
• Students and newcomers learning how OCPP works by watching real message exchanges.

Building the CSMS in Node.js? The simulator is built on the same library you can use for the server — see OCPP in Node.js with ocpp-ws-io.