OCPI (Open Charge Point Interface) is an open protocol that enables interoperability between EV charging platforms—primarily between Charge Point Operators (CPOs) and eMobility Service Providers (eMSPs). OCPI standardizes how platforms exchange data for roaming, including charger locations, real-time status, tariffs, and charging session records, so drivers can access multiple networks with one app or contract.
What OCPI is used for
OCPI is commonly used to support:
– Roaming access (authorization and session enablement across networks)
– Location and connector data exchange (where chargers are, what they support)
– Status updates (available, occupied, out of service)
– Tariff exchange (prices, fee structures, currency, conditions)
– Session records (kWh delivered, time, costs, start/stop)
– CDRs (Charge Detail Records) for billing and settlement
– Optional support for tokens (RFID/app identifiers) and contract-based access
How OCPI works at a high level
OCPI connects back-office systems rather than charger hardware:
– The CPO platform manages chargers and publishes locations, statuses, and session data
– The eMSP platform manages end users, contracts, and billing relationships
– OCPI APIs allow these platforms to synchronize data and exchange session/billing records
– Settlement is handled between parties based on agreed commercial terms
OCPI is typically implemented as RESTful APIs with defined modules and versioning.
Why OCPI matters in EV charging
OCPI is a key enabler of a seamless driver experience across networks:
– Reduces “app fragmentation” by enabling multi-network access
– Improves charger discovery with consistent data feeds to eMSP apps
– Supports transparent pricing by exchanging tariffs and conditions
– Enables cross-network billing through standardized CDRs
– Helps CPOs increase utilization by attracting roaming users
OCPI vs OCPP
OCPI and OCPP serve different layers of the ecosystem:
– OCPP: communication between the charger and the CPMS/back office (control, monitoring, firmware, transactions)
– OCPI: communication between back-office platforms (CPO ↔ eMSP) for roaming, locations, tariffs, sessions, and billing records
Many networks use both: OCPP for operating chargers and OCPI for roaming interoperability.
Key OCPI concepts
Common OCPI concepts include:
– Locations: site, EVSE, connector details used for discovery and routing
– Tokens: identifiers used for authorizing users (RFID/app-based)
– Tariffs: pricing definitions shared for user display and billing logic
– Sessions: live or near-real-time charging session data
– CDRs: finalized records used for invoicing and settlement
– Modules: functional API groups (e.g., locations, tariffs, sessions, tokens)
Implementation considerations and pitfalls
– Data quality is critical: inaccurate locations/status leads to failed user journeys
– Align definitions (availability, occupied, faulted) to avoid mismatched app displays
– Keep tariff rules consistent and transparent to reduce billing disputes
– Ensure strong security (TLS, auth tokens, allow-listing) for API connections
– Define operational processes for exceptions: failed starts, partial sessions, refunds, chargebacks
– Monitor interoperability KPIs: roaming success rate, CDR reconciliation rate, dispute rate
Related glossary terms
Roaming
eMSP
CPO
Interoperability networks
Multi-network access
Interoperability billing
Cross-network authentication
Charge Detail Record (CDR)
Tariffs and pricing models
OCPP