These two acronyms look almost identical, which is exactly why people keep mixing them up.
Here's the quick difference first: OCPP connects chargers to management systems. OCPI connects charging businesses to each other.
That is the cleanest way to think about it.
If a charger is talking to a central system or backoffice, you are in OCPP territory. If different charging platforms are exchanging roaming, session, tariff, or authorization data, you are usually in OCPI territory. The driver, meanwhile, just sees an app, RFID card, or payment screen.
Why people keep mixing up OCPI and OCPP
The confusion is understandable.
Both terms belong to EV charging. Both sit in the background. Both can matter in the same real-world setup. And both are usually invisible to the driver.
So people see one charging experience and assume one protocol must be doing everything.
It is not.
There are layers. The charger still needs to talk upstream. A platform still needs to manage sessions and authorization. If roaming is involved, charging businesses may also need to exchange data with each other. Same industry, similar acronym, completely different job.
What OCPP actually does
OCPP is the protocol that lets a charger talk to a central system. In plain English, it is the charger-to-backoffice communication layer.
That is where things like these usually happen:
- charger status updates
- remote start and stop
- meter values and session data from the charger
- diagnostics and configuration
- firmware handling
- smart charging support
So when someone says a charger is "OCPP compatible," they are talking about how that charger connects to a management platform or OCPP backoffice.
That matters because it affects flexibility. A charger that speaks OCPP is generally easier to connect to different systems instead of being stuck in one closed vendor stack.
What OCPI actually does
OCPI does a different job.
OCPI is the protocol that helps different charging businesses recognise each other, exchange charging-session data, and make roaming work.
This is the platform-to-platform side of the map. Think of a charge point operator on one side and a mobility service provider on the other. They may need to exchange things like:
- location and charger information
- token or authorization data
- tariffs
- sessions
- CDRs
- command flows related to interoperability
That does not mean OCPI is the protocol inside the charger. It is not.
A simple way to say it is this: OCPP is charger-to-backoffice. OCPI is network-to-network.
And one important nuance: platforms like Hubject or Gireve may sit in this world, but they are not "the same thing as OCPI." OCPI is a protocol. A hub is a business or platform layer.
What happens when someone taps a charge card
Here is a practical version, because this is where the confusion usually clears up.
- 2.A driver taps a charge card or starts a session in an app.
- 4.The charger talks to its connected central system through OCPP.
- 6.If roaming is involved, the commercial side may exchange token, session, or tariff data through OCPI or a similar setup.
- 8.If authorization succeeds, the session starts.
- 10.The session data is recorded and later used for invoicing, settlement, or reimbursement.
That is the basic shape.
Not every charging setup uses exactly the same architecture. Some are direct. Some use hubs. Some mix multiple layers. But the key distinction still holds: the charger talks OCPP, while the roaming or interoperability layer often talks OCPI.
If you want more context around who does what on the commercial side, operators explained is useful. And if you want to see how sessions show up in practice, view charging transactions is a good follow-up.
Do you need OCPI for a home or business charger?
Usually, not directly.
For many home-charging setups, the immediate questions are much simpler:
- Does the charger speak OCPP?
- Can it connect to the right billing or backoffice system?
- Is reimbursement supported?
- Does the meter and installation meet local requirements?
That is why many home users mostly care about OCPP, backoffice compatibility, and whether they can connect to a billing provider. They do not usually need to obsess over roaming protocols.
OCPI becomes more relevant once you move into things like:
- public charging access
- roaming between networks
- multi-party platform integrations
- broader interoperability between charging businesses
So if you are choosing a home setup for reimbursement, OCPI is usually not the first thing to worry about. A better place to start is your home charging setup, whether automatic billing with Volt Time fits your case, and how a backoffice explained setup works.
Where Plugchoice fits if you want flexibility
This is the part that matters commercially.
Plugchoice is strongest on the OCPP / backoffice / flexibility side of the map.
In other words, Plugchoice is not the thing to describe as a universal roaming hub or a universal billing platform. That would be too broad, and it would not be accurate.
The stronger and more honest framing is that Plugchoice helps you keep chargers flexible, and that its OCPP Proxy approach can help connect chargers to third-party backends and billing operators without forcing you into one vendor path.
That matters when you want less lock-in, more integration freedom, and a clearer separation between charger communication, operational control, and commercial services.
For the operational layer, the web portal is the better reference point than calling Plugchoice "the roaming platform." That keeps the architecture honest.
The takeaway
If you remember one sentence, make it this:
OCPP connects chargers to management systems. OCPI connects charging businesses to each other.
So:
- the charger talks OCPP
- the roaming layer often talks OCPI
- the driver sees a card, app, or payment screen
- Plugchoice matters most on the OCPP, backoffice, and flexibility side
That is why the two terms show up in the same projects, but they are not interchangeable.