What is OCPP? A Complete Guide to Open Charge Point Protocol (2026)
OCPP (Open Charge Point Protocol) is the open standard that lets an EV charger talk to backend management software (CSMS) regardless of who built either side. OCPP 1.6 is the workhorse; OCPP 2.0.1 adds plug-and-charge and smarter security. If you operate, procure, or build EV charging in India, OCPP compliance is the single most important spec on the sheet.
Definition
The Open Charge Point Protocol (OCPP) is an open-source application protocol that defines how an EV charging station (called a "charge point") communicates with a central Charging Station Management System (CSMS). It was first published in 2010 by ElaadNL and is now maintained by the Open Charge Alliance (OCA), a non-profit with more than 220 member companies worldwide.
OCPP is to EV charging what SMTP is to email: a vendor-neutral contract that lets any compliant charger work with any compliant backend. Without OCPP, every operator would be locked into their charger manufacturer's cloud forever.
OCPP versions explained
Legacy SOAP-based version from 2012. Effectively obsolete — you should not deploy this today.
Released 2015. The most widely deployed version in India and globally. Two transports: SOAP (deprecated) and JSON over WebSockets (1.6J — what everyone actually uses). Supports core charging, firmware management, local auth list, reservations, and smart charging.
Released 2018 but rapidly superseded by 2.0.1. Skip this.
Released 2020. The current target standard. Adds ISO 15118 plug-and-charge, advanced device management, security profiles 1-3 (TLS + client certificates), tariffs, display messages, and improved smart charging. Backwards-incompatible with 1.6 at the message level.
Core OCPP message types
OCPP is bidirectional. The charger initiates some messages, the CSMS initiates others. The essential message types you need to know:
- BootNotification — charger registers with CSMS on startup.
- Heartbeat — periodic ping so the CSMS knows the charger is alive.
- StatusNotification — reports connector state (Available, Preparing, Charging, Faulted, etc.).
- Authorize — charger asks CSMS whether an RFID/app token is valid.
- StartTransaction / StopTransaction — charging session lifecycle.
- MeterValues — periodic energy / current / voltage / SoC readings during a session.
- RemoteStartTransaction / RemoteStopTransaction — CSMS-initiated session control (e.g. from a mobile app).
- UpdateFirmware / GetDiagnostics — remote maintenance.
- SetChargingProfile — smart charging schedules and load balancing.
Why OCPP matters
- No vendor lock-in. You can swap your CSMS without replacing the chargers and vice versa.
- Mixed-vendor fleets. A single CSMS can manage Delta, ABB, Exicom, Servotech, Mass-Tech, and Statiq hardware side-by-side.
- Roaming. OCPP feeds session data into OCPI, which is what powers cross-network roaming via aggregators like Hubject and Gireve.
- Open ecosystem. Mobile apps, billing platforms, fleet tools, and analytics dashboards can all integrate at the CSMS layer once.
Who uses OCPP?
Anyone building, operating, or integrating with EV charging infrastructure:
- · CPOs (Charge Point Operators) — Tata Power, Statiq, Recharge India, Charge Zone, glida.
- · Charger OEMs — Delta, ABB, Servotech, Exicom, Mass-Tech, Numocity hardware partners.
- · CSMS / software vendors — AMPECO, ChargePoint, Etrel, EV.energy, and platforms like our plugEV CSMS.
- · Fleet operators — e-commerce delivery, ride-hail (BluSmart), bus depots, logistics fleets.
- · Commercial real estate — malls, offices, residential societies with shared chargers.
Common OCPP implementation challenges
- Vendor-specific quirks. "OCPP compliant" chargers often interpret optional fields differently. Real-world testing matters more than the spec sheet.
- WebSocket reliability. Chargers in basement parkings with weak 4G need aggressive reconnect logic and message queuing.
- Time synchronisation. Heartbeat drift, missing NTP, and timezone bugs corrupt MeterValues timestamps and break billing.
- Local mode behaviour. What happens when the charger loses internet mid-session? OCPP defines local auth lists and offline transactions but each OEM ships its own quirks.
- 1.6 vs 2.0.1 in the same fleet. Most production CSMS in India must dual-stack indefinitely.
OCPP vs proprietary protocols
Some OEMs still push proprietary cloud protocols (often labelled "cloud-managed" chargers) because lock-in protects their recurring revenue. The trade-off is brutal: you save a few thousand rupees per charger upfront and lose the ability to ever change software vendor. For any deployment above 10 chargers, OCPP compliance pays for itself within a year through pricing leverage at CSMS renewal time alone.
Common questions about OCPP
What does OCPP stand for?
OCPP stands for Open Charge Point Protocol. It is maintained by the Open Charge Alliance (OCA), a non-profit consortium of EV infrastructure vendors. OCPP is an open standard — anyone can implement it, on either the charger side or the backend (CSMS) side, without paying licensing fees.
Which OCPP version should an Indian CPO use in 2026?
OCPP 1.6J (JSON over WebSocket) is still the most widely deployed version in India because almost all chargers shipped between 2019-2024 support it. OCPP 2.0.1 is the future and is required if you want ISO 15118 plug-and-charge, smart charging, or improved security profiles. Most Indian CPOs run hybrid backends that speak both 1.6 and 2.0.1.
Is OCPP mandatory in India?
There is no central legal mandate, but the Ministry of Power's revised EV charging guidelines and BIS standards (IS 17017) effectively assume open protocols. State EV policies (Maharashtra, Delhi, Karnataka) and most tenders for public charging now require OCPP compliance to qualify.
What is a CSMS?
CSMS stands for Charging Station Management System — the backend software that OCPP chargers connect to. The CSMS handles authentication, transactions, billing, remote start/stop, firmware updates, smart charging schedules, and roaming. Examples include AMPECO, ChargePoint, EV.energy, Etrel, and our own plugEV platform.
Can a proprietary charger be made OCPP-compliant?
Sometimes — through a firmware update if the manufacturer has prepared an OCPP build, or via a hardware OCPP gateway that sits between the charger's Modbus/CAN interface and the internet. Retrofitting is rarely as clean as buying an OCPP-native charger, and you may lose features the OEM's cloud provided.
What is the difference between OCPP and OCPI?
OCPP runs between a charger and its CSMS. OCPI (Open Charge Point Interface) runs between CSMS systems — for roaming, eMSP integrations, and tariff exchange. A CPO uses OCPP to manage its own chargers and OCPI to let other apps (Tata Power EZ, Statiq, Recharge India) initiate sessions on them.
Why do EV charger tenders specify OCPP compliance?
Vendor lock-in is the dominant pain in EV infrastructure. If a CPO buys 200 chargers from Vendor A on Vendor A's proprietary protocol, they cannot swap CSMS later, add Vendor B chargers to the same backend, or join a national roaming network. OCPP compliance is the cheapest insurance against this.
Related reading
Need help implementing OCPP?
We've shipped OCPP 1.6 and 2.0.1 backends, mobile apps, and roaming integrations for Indian CPOs. Get in touch— happy to share what works and what doesn't before you commit.