OCPP (Open Charge Point Protocol) is the language an EV charger uses to talk to its management software. OCPI (Open Charge Point Interface) is the language charging networks use to talk to each other, so a driver using one network’s app can find, start and pay for charging on another network’s chargers — known as roaming. In short: OCPP connects chargers to a backend; OCPI connects backends to each other.
Last updated: September 2026.
OCPP vs OCPI at a Glance
| OCPP | OCPI | |
|---|---|---|
| Full name | Open Charge Point Protocol | Open Charge Point Interface |
| Connects | A charger and its charging station management system (CSMS) | A charge point operator (CPO) and e-mobility service providers (eMSPs) or other networks |
| Purpose | Control and monitor chargers: start/stop sessions, meter readings, status, firmware updates, smart charging | Roaming: share charger locations, availability, tariffs, sessions and billing records between networks |
| Maintained by | Open Charge Alliance | EVRoaming Foundation |
| Common versions | 1.6J, 2.0.1, 2.1 | 2.2.1 |
| Who cares most | Charger manufacturers and charging station owners | Charging networks, app providers and drivers |
What Is OCPP?
OCPP (Open Charge Point Protocol) is an open, vendor-neutral protocol for communication between an EV charger and the central software that manages it, usually called a CSMS (charging station management system). Because it is open, a charging station owner can combine chargers from one manufacturer with software from another, and switch either later without replacing everything.
What OCPP lets a network do
- Authorise and start or stop sessions — from an app, a QR code or an RFID card.
- Read meter values for accurate per-kWh billing.
- Monitor charger status — available, charging, faulted or offline — in real time.
- Run smart charging, sharing limited grid power across several chargers.
- Update firmware and diagnose faults remotely, reducing site visits and downtime.
OCPP versions
- OCPP 1.6J — the most widely deployed version, using JSON over WebSocket. Most chargers in India support it.
- OCPP 2.0.1 — adds a richer device model, stronger security profiles, improved smart charging and support for ISO 15118 “Plug & Charge”. It has also been published as the international standard IEC 63584.
- OCPP 2.1 — the latest version, adding features such as bidirectional charging (vehicle-to-grid) support.
Example of OCPP in action
A driver scans the QR code on a DC fast charger. The app asks the CSMS to start a session; the CSMS sends a remote-start command to the charger over OCPP. During charging, the charger reports meter values every few seconds; when the driver stops, the charger sends the final reading and the CSMS calculates the bill.
What Is OCPI?
OCPI (Open Charge Point Interface) is an open protocol that connects the backend systems of different charging businesses. It lets a charge point operator (CPO) — the company that runs the chargers — share its network with an e-mobility service provider (eMSP) — the company whose app or card the driver uses.
What OCPI shares between networks
- Locations — where chargers are, their connectors and live availability.
- Tariffs — the price a driver will pay.
- Tokens — which app accounts or RFID cards are allowed to charge.
- Sessions and commands — starting and stopping charging remotely from another network’s app.
- Charge detail records (CDRs) — the final record of each session, used to settle payments between the companies.
Why OCPI matters for drivers
Without roaming, a driver needs a separate app and account for every network. With OCPI, one app can show and start chargers from several networks, and the networks settle the payment between themselves in the background. That is what makes “one app for all chargers” possible.
How OCPP and OCPI Work Together
- A driver opens an eMSP’s app and selects a charger that belongs to a different network.
- The eMSP sends the start request to the CPO’s backend over OCPI.
- The CPO’s backend starts the charger over OCPP.
- The charger reports energy to the CPO over OCPP; the CPO shares the session and final record with the eMSP over OCPI.
- The driver pays the eMSP, and the eMSP pays the CPO.
Other EV Charging Protocols You May Hear About
- ISO 15118 — communication between the car and the charger, enabling Plug & Charge (the car identifies itself automatically).
- OSCP (Open Smart Charging Protocol) — shares grid capacity forecasts between an electricity network operator and a charging operator.
- OpenADR — used by utilities to send demand-response signals to reduce or shift charging load.
Why Open Protocols Matter If You Own a Charging Station
- No vendor lock-in: OCPP-compliant chargers can move to a different CSMS if you change software provider.
- More customers: OCPI roaming puts your chargers in more drivers’ apps.
- Lower running costs: remote monitoring, diagnostics and firmware updates reduce downtime and site visits.
- Future-proofing: newer OCPP versions add Plug & Charge and vehicle-to-grid support.
EarthtronEV’s charging stations use OCPP 1.6J / 2.0.1 chargers and support OCPI 2.2.1 roaming, managed through our own charging station management system (CSMS). See how we implement both on our OCPP and OCPI page, or, if you are planning to invest in a station, our EV charging station franchise. For drivers, see how to pay for EV charging in India.
Related Reading
- Cybersecurity for EV Charging Stations: Protecting Chargers, Payments and Customer Data
- How to Pay for EV Charging in India: Apps, UPI, RFID and Costs (2026)
- Top EV Charger Manufacturers and Charging Companies in India (2026)
Frequently Asked Questions
What is the difference between OCPP and OCPI?
OCPP connects an EV charger to its management software, so the operator can control, monitor and bill charging sessions. OCPI connects different charging networks and apps to each other, so drivers can roam — use one app on several networks.
What is OCPI in EV charging?
OCPI (Open Charge Point Interface) is an open protocol for EV charging roaming. It lets charge point operators share charger locations, tariffs, sessions and billing records with e-mobility service providers and other networks.
What is OCPP used for?
OCPP is used for communication between a charger and its central management system: starting and stopping sessions, reading meter values for billing, monitoring status, smart charging and remote firmware updates.
What are CPOs and eMSPs?
A charge point operator (CPO) owns or operates charging stations and is responsible for the chargers, uptime and pricing. An e-mobility service provider (eMSP) provides the app or RFID card drivers use to find, start and pay for charging. Sometimes one company is both; OCPI is what connects different CPOs and eMSPs so drivers can charge across networks.
Which OCPP version should a new charger support?
At minimum OCPP 1.6J, which almost every CSMS supports. OCPP 2.0.1 support is worth having for stronger security, better smart charging and Plug & Charge readiness.
Do drivers need to know about OCPP or OCPI?
Not directly. Drivers see the results: reliable app-based start and payment (OCPP) and the ability to use more chargers from one app (OCPI).