What is OCPP? The open standard between charge point and backend
The one sentence of context
OCPP (Open Charge Point Protocol) is the common language between the charge point and the backend of the Charge Point Operator (CPO). Without it, operators would have to adapt their infrastructure to every vendor-specific system.
1. What OCPP means
Open Charge Point Protocol , short for OCPP, is a communication standard that is published by the Open Charge Alliance (OCA) . It enables the data transfer between charging stations for electric vehicles and backend systems.
The backend is the central software that processes the data and enables the monitoring, control, and billing of the charging sessions. OCPP allows both systems to communicate in a common "language" — and to handle various functions:
- Authentication of charging sessions
- Remote control — start and stop a charging session, adjust the power
- Data exchange — state of charge, energy consumption, timestamps
- Firmware management — software updates of the station without a workshop
- Fault reporting — error codes to the backend
2. Which formats does OCPP run on?
This communication can occur in two different ways:
| Format | Characteristics | Typical use |
|---|---|---|
| SOAP | XML-based format | older OCPP versions, systems with strict schema validation |
| JSON | simpler and more efficient format | modern web applications, current OCPP versions |
The backend processes the data it receives and, based on that, can monitor the charging infrastructure, adjust charging profiles, and create billing records.
3. Why an OCPP interface matters
Because OCPP ensures interoperability between charging stations from different vendors. Charging-infrastructure operators are therefore not tied to a specific vendor and can integrate different charging stations in a unified backend.
The point that matters most for you as a driver
When a CPO can buy charge points from a different vendor and integrate them into its existing network, the security of the investment improves. In practice, this means:
- Charging networks have a broader choice of stations than there are vendors
- A provider can take over stations when a competitor exits the business — or merge charging networks
- Location and operator can change independently of each other
In short: OCPP keeps the charging infrastructure open, and so more competitive.
4. Where OCPP is established
OCPP has established primarily in Europe and Asia — but not in the US, where proprietary solutions and the vendor's own ecosystems (e.g., Tesla) remain large.
5. The versions: OCPP 1.6, 2.0.1 and 2.1
OCPP is not a dead standard — the OCA keeps developing it. In practice two major versions are active: the established 1.6 and the newer 2.0.1, to which the market is increasingly switching. Starting from 2025 this is supplemented by 2.1, continuing the 2.x line.
| Version | Year | Key improvement |
|---|---|---|
| OCPP 1.6 | 2015 | Smart Charging (Load Balancing, Charge Profiles), JSON over WebSockets (in addition to SOAP), more status reports — still today the most widely deployed version on existing stations |
| OCPP 2.0.1 | 2020 | Ground-up reconstruction (not backward compatible): JSON-only, transactions as TransactionEvent, structured device model, security profiles (Security Profiles), ISO 15118 Plug & Charge, signed firmware, WebSocket compression — Edition 3 2024 recognized as IEC Standard (IEC 63584) |
| OCPP 2.1 | 2025 | Continuation of the 2.x line, backward compatible with 2.0.1 — the OCA announces it as the foundation for the years to come |
The main differences: 1.6 vs. 2.0.1
| Aspect | OCPP 1.6 | OCPP 2.0.1 |
|---|---|---|
| Message format | SOAP or JSON | JSON (SOAP is dropped) |
| Transactions | Start/Stop messages, separate MeterValues | unified TransactionEvent, configurable start/stop points (plugging in/out, parking space) |
| Security | TLS optional (Security whitepaper as addendum) | Security profiles (Security Profiles) mandatory (Profiles 1–3, including mTLS), signed firmware, certificate management |
| Plug & Charge | not natively possible (workaround via Application Note) | ISO 15118 natively integrated |
| Configuration | flat Config keys | structured device model (variable-based) |
| Offline behavior | temporary transaction-IDs, exchange after reconnect | station-internal ID + sequence numbers, gapless replay |
Important: 1.6 and 2.0.1 do not speak with each other
OCPP 2.0.1 is not an incremental upgrade, but a standalone standard. A station that only speaks OCPP 1.6 cannot communicate with a 2.0.1-capable backend — and vice versa. In practice, this means:
- Backends (CPMS) of the CPOs typically offer both versions in parallel — the station reports its version at the WebSocket handshake
- New stations are increasingly being shipped with 2.0.1
- The large majority of the installed base is still on 1.6 — the OCA has not announced an official end-of-life for 1.6
Nothing changes for you as a driver — the version runs unnoticed in the background.
6. OCPP vs. OCPI — two protocols, two layers
A common misunderstanding: OCPP (station ↔ backend) is often confused with OCPI (Open Charge Point Interface, CPO ↔ eMSP). Both are open standards, both concern charging — and both run in parallel:
| OCPP | OCPI | |
|---|---|---|
| Between | Charging station (CS) and CPO backend (CSMS) | CPOs and eMSPs / Roaming platforms |
| Enables | Control, fault reporting, firmware, Smart Charging | data (stations, prices, availability), authorization, billing across network boundaries |
| Like | Telephone ↔ central switch | Switch ↔ switch (Roaming) |
OCPP and OCPI together form the technical foundation of the charging ecosystem — on top of which CPOs, eMSPs, and roaming platforms ( the role overview) sit.
7. OCPP in practice
A proper implementation of OCPP on both sides — charge point and backend — is decisive for smooth communication. In typical workflows the station controls the charging session; the backend handles authentication, authorization, and fault reporting.
When a charge point is no longer reachable from the backend or causes firmware issues, the cause in many cases is an OCPP-instability — that's the most common technical error situation, that CPOs must fix (more on the roles under What is a CPO).
LadeGuide plans your charging stops based on your card, tariff, and charging curve
Regardless of the vendor of the charge point or which CPO is behind it — the app calculates your cheapest option.
Learn moreSources
- Open Charge Alliance: OCPP.org — Open Charge Alliance & OCPP standard
- Next Mobility: CPO and eMSP: role clarification, interoperability and market logic through AFIR
- National Lade-Service: Glossary charging infrastructure