Imagine driving across India and discovering that every petrol station only accepted its own membership card. You’d have to download a different app, create a new account, and make a separate payment every time you stopped to refuel. 

That would be frustrating. 

Sounds exhausting, doesn’t it? That’s exactly the kind of fragmented experience EV drivers would face without shared standards in charging networks. Without a common communication standard, every EV charging network could end up operating in isolation, making charging inconvenient for drivers and difficult for businesses to manage. 

This is where EV charging communication protocols come in. 

Standards such as Open Charge Point Protocol (OCPP) and Open Charge Point Interface (OCPI) help chargers, software platforms, and charging networks communicate using a common language. This standardization is what makes today’s public EV charging ecosystem possible. Although they’re often compared, they serve very different purposes.  

Understanding the difference between OCPP and OCPI is crucial for anyone planning EV charging infrastructure, operating a charging network, or simply wanting to know how public charging works. 

In this guide, you’ll learn what each protocol does, how they work together, and why both are essential for building a seamless EV charging ecosystem. 

What is OCPP? 

OCPP (Open Charge Point Protocol) is the communication standard that allows an EV charger to communicate with its Charging Management System (CMS). 

Think of OCPP as the bridge between the physical charger and the software used to manage it. 

Whenever an operator wants to check if a charger is online, update its software, monitor charging sessions, or receive fault alerts, that communication happens through OCPP. 

Without OCPP, every charger manufacturer would need proprietary software, making it difficult for businesses to manage chargers from different brands. 

How OCPP Works 

Key Features of OCPP 

OCPP makes EV charging stations easier to manage, maintain, and scale. It enables:  

• Remote monitoring of charger status, availability, and sessions in real time from a central dashboard. 

• Remote start and stop of charging sessions. 

• Over-the-Air (OTA) firmware updates to improve performance, add new features, and address security vulnerabilities. 

• Real-time charger fault detection and diagnostics, facilitating faster troubleshooting and reduced downtime. 

• Smart charging, where the central system optimizes charging based on grid capacity, electricity tariffs, or user preferences. 

• Dynamic load management, allowing the central system or a local controller to distribute available electrical power across multiple chargers to prevent overloads and improve energy efficiency. 

• User authentication via RFID cards, mobile apps, or other approved methods, typically routed through the central system before a charging session begins. 

• Transaction and energy reporting by recording charging sessions, energy consumption, and transaction details to support billing, reporting, and operational analysis. 

• Vendor independence by allowing charging stations to work with compatible Charging Management Systems (CMS), reducing reliance on proprietary software. 

• Scalability by making it easier to add new chargers, sites, or software integrations as charging infrastructure expands. 

What is OCPI? 

OCPI (Open Charge Point Interface) is an open communication protocol that allows different EV charging networks to share information. It enables features such as EV roaming, charger discovery, and seamless payments across multiple networks. 

While OCPP manages communication between a charger and its backend software, OCPI connects the businesses behind those chargers. 

How OCPI Works 

Here’s a simplified view of how OCPI works. 

Imagine Priya uses App A to locate and pay for charging sessions. On a highway, she finds a charger that belongs to Network B. 

Without OCPI: 

• App A cannot communicate with Network B.  

• Priya must download another app, create an account, and pay separately.  

With OCPI: 

• App A communicates with Network B through OCPI.  

• Priya starts charging with her existing app, while the two companies exchange session and payment details securely in the background.  

From the driver’s perspective, the experience feels seamless. 

Key Features of OCPI  

Open Charge Point Interface (OCPI) is a protocol that enables roaming between EV drivers, e-Mobility Service Providers (eMSPs), and Charge Point Operators (CPOs), allowing drivers to use charging stations outside their home network through a single app.   

• OCPI enables roaming by allowing an eMSP’s app to authorize and start charging sessions at stations operated by a different CPO without requiring direct commercial or technical integrations between every network. 
   

• It supports location and status sharing, with CPOs publishing real-time data on charging station locations, connector types, availability, and operational status to connected eMSPs. 
   

• It facilitates dynamic pricing and tariff exchange, enabling CPOs to share per-kWh rates, session fees, time-based pricing so eMSPs can display accurate costs to drivers before charging. 
   

• It provides remote authorization by validating a driver’s token (app credential or RFID) with the CPO in real time before a charging session begins 
  . 

• It supports session management, allowing charging sessions to be started or stopped remotely while tracking live session data as it progresses. 
   

• It standardizes charge detail records (CDRs), ensuring completed sessions include energy delivered, duration, and cost to support automated settlement between CPOs and eMSPs. 
   

• It offers peer-to-peer or hub-based connectivity, supporting either direct bilateral connections or routing through a roaming hub to reach multiple partner networks with on integration. 
   

• It uses a RESTful, stateless architecture based on HTTPS/JSON API calls, distinguishing it from OCPP’s persistent charger-to-CMS communication. 
   

• It ensures vendor and network independence by working across different CMS platforms and charging networks, reducing the need for custom point-to-point integrations. 

• Finally, OCPI continues to evolve, with version 2.2.1 widely adopted today and version 3.0 adding support for ISO 15118 and Plug & Charge capabilities. 

Difference Between OCPI and OCPP 

The difference between OCPP and OCPI is that OCPP manages the charger, and OCPI connects charging networks. 

Feature	OCPP	OCPI
Full Form	Open Charge Point Protocol	Open Charge Point Interface
Primary Purpose	Manage EV chargers	Connect charging networks
Communicates Between	EV Charger ↔ CMS	CPO ↔ eMSP
Main Users	Charger manufacturers, CPOs	CPOs, eMSPs
Controls	Charger operations	Roaming and data exchange
Supports	Remote monitoring, diagnostics, firmware updates	Charger discovery, authentication, payments
Typical Deployment	Individual charging stations	Public charging ecosystems

Let’s break down how they work together in the EV charging ecosystem: 

1. The EV driver opens a charging app and selects a nearby charger.  

2. The app communicates with the Charging Point Operator through OCPI to verify charger availability and authorize the charging session.  

3. The CPO sends the request to its Charging Management System. 

4. The CMS communicates with the physical charger using OCPP.  

5. The charger starts the session, and once complete, details flow back through the same chain for billing and payment. 

The driver experiences a seamless process, even though multiple systems are working together in the background. 

Who Uses Each Protocol? 

Stakeholder	Uses OCPP	Uses OCPI
Charger Manufacturer	✔
Charging Point Operator (CPO)	✔	✔
eMobility Service Provider (eMSP)		✔
Fleet Operator	Indirectly	Indirectly
EV Driver	No	Benefits from it
Charging Management Software	✔	✔

Common Misconceptions About OCPP and OCPI 

Several misconceptions often create confusion around EV charging protocols. 

• “OCPI replaces OCPP.” Incorrect. OCPI and OCPP serve different purposes. OCPP manages communication between chargers and the charging management system, while OCPI connects charging networks and e-mobility service providers. 

• “You only need one protocol.” Not always. Private charging setup may only need OCPP, but public networks benefit from both. 

• “OCPP and OCPI perform the same function.” No. OCPP focuses on charger operations, while OCPI focuses on interoperability. 

• “These protocols only matter for large networks.” Not true. Even smaller networks benefit from open communication standards. Using interoperable protocols today makes it easier to scale operations, integrate new software, and participate in larger charging ecosystems in the future.