Introduction

The Unified Health Interface (UHI) is an open network for digital health services in India. The National Health Authority (NHA) operates the network under the Ayushman Bharat Digital Mission (ABDM). UHI connects any patient application to any provider platform through 1 open protocol. A patient can find, book, and track health services from any application on the network.

The current UHI core protocol version is 0.7.1.

The 3 participants

Each UHI transaction involves 3 participants:

Participant	Full name	Role
EUA	End User Application	The patient-facing application. It sends search requests and shows the results.
HSPA	Health Service Provider Application	The provider-side platform. It holds the service catalog and answers with on_search.
Gateway	UHI Gateway	The routing layer that the NHA operates. It broadcasts each search to all registered HSPAs.

A Health Service Provider (HSP) is the real hospital, clinic, or pharmacy. The HSPA is the digital interface to the HSP.

sequenceDiagram
  participant EUA
  participant Gateway as UHI Gateway
  participant HSPA
  EUA->>Gateway: POST /search
  Gateway-->>EUA: ACK
  Gateway->>HSPA: POST /search (broadcast)
  HSPA-->>Gateway: ACK
  HSPA->>Gateway: POST /on_search (catalog)
  Gateway->>EUA: POST /on_search (to consumer_uri)

How the network operates

• Each API call is asynchronous. The receiver returns an HTTP 200 ACK at once. The business data arrives later at a callback URL.
• Each call carries a common context block. The block holds the domain, the action, and the transaction ID.
• Each call is signed with an Ed25519 signature. See Network and protocol.
• Discovery goes through the Gateway. For services with a booking flow, the booking calls go point-to-point (P2P) between the EUA and the HSPA.

Services on UHI

Each service has a fixed domain code. The domain code selects the service in every API call.

Service	Domain code	Scope in Phase 1
Physical Consultation	nic2004:85111	Full lifecycle: discovery, booking, fulfilment, post-fulfilment
PM-JAY Hospital Discovery (HEM)	nic2004:85112	Discovery only (search / on_search)
Blood Bank Discovery	nic2008:86906	Discovery only (search / on_search)
Ambulance Booking	nic2008:86909	Discovery and booking (search, on_search, init, on_init)
Jan Aushadhi Kendra Discovery	nic2008:47721	Discovery only, outlets and medicine stock
AMRIT Pharmacy Discovery	nic2025:477201	Discovery only, outlets and medicine stock

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