Build with the Omni API

The Omni API gives you programmatic access to Engine’s hotel booking platform — the same technology powering Engine’s own product, which serves thousands of businesses. Integrate hotel shopping, pricing, and booking into your product through gRPC or HTTP/JSON interfaces, or refer your customers to a streamlined Engine checkout flow to complete and manage their booking.

Table of contents

Build with the Omni API

What is the Omni API?

The Omni API gives you programmatic access to Engine’s hotel booking platform. Whether you’re a travel platform adding hotels, a corporate perks provider building employee benefits, or a fintech provider expanding your offering, the Omni API provides the tools to ship a production-ready booking experience without building a travel technology infrastructure from scratch.

What you get access to

Through the Omni API, your integration taps into:

Property discovery and content (names, addresses, images, descriptions, amenities)
Real-time rate shopping with best offers and availability details
Full booking lifecycle including confirmation, cancellation preview, and cancellation
Engine-branded folio (PDF) generation for real-time booking documentation

Core concepts: the booking lifecycle

The Omni API organizes lodging transactions into four sequential stages. Unlike e-commerce where inventory is stable, hotel availability changes in real time. The API architecture simplifies travel for your customers.

---
title: The Engine Booking Lifecycle
---
flowchart LR
    fp["Find Properties<br/><code>ListProperties</code>"]
    sr["Shop Rates<br/><code>FindBestOffers</code> / <code>FindAvailability</code>"]
    tx["Transact<br/><code>ConfirmOffer</code> → <code>Book</code>"]
    mg["Manage<br/><code>GetBookings</code> / <code>SubmitCancellation</code>"]

    fp --> sr --> tx --> mg

Find Properties — ListProperties looks up by geo, address, or text.
Shop Rates — FindBestOffers and FindAvailability return pricing and room details.
Transact — ConfirmOffer locks the rate, then Book confirms.
Manage — GetBookings, SubmitCancellation, and folio generation handle the post-booking lifecycle.

Key data relationships

Each step in the lifecycle produces a data object that feeds into the next. There are two entry points into the shopping flow — ListProperties for property data without pricing, or FindBestOffers when pricing is needed to pick a property — but both converge at FindAvailability before booking. Understanding this chain is essential for building a correct integration.

---
title: Data Model — Entity Flow
---
flowchart LR
    lp["ListProperties"] --> property["Property<br/><i>Static content: name, address,<br/>images, amenities</i>"]
    fbo["FindBestOffers"] --> bo["BestOffer<br/><i>Best price per property +<br/>continuation_token</i>"]
    property --> fa["FindAvailability"]
    bo --> fa
    fa --> rg["RoomGroup<br/><i>Each RoomGroup represents one room type<br/>and contains one or more Offers with<br/>different amenities and conditions.</i>"]
    rg --> co["ConfirmOffer"]
    co --> quote["Quote<br/><i>Locked price, purchasable for<br/>a limited window</i>"]
    quote --> book["Book"]
    book --> booking["Booking<br/><i>Confirmed reservation with<br/>guest details & itinerary</i>"]

    classDef stable fill:#fff,stroke:#dcd9de,stroke-width:2px
    classDef confirmed fill:#fff,stroke:#34a853,stroke-width:2px
    class property,bo,rg stable
    class quote,booking confirmed

Stable — static content that does not change between requests.
Confirmed — pricing is locked for a limited window.

How continuation_token works

FindBestOffers returns a continuation_token with each BestOffer. Pass this token to FindAvailability to retrieve detailed room groups and offers for that property. Alternatively, you can call FindAvailability directly with a property ID — the token simply carries shop criteria forward for more accurate results.

Example: get the best price for hotels in a given area

The Omni API is offered over gRPC (protocol buffers) and HTTP/JSON. Both interfaces cover the same booking lifecycle, but gRPC can offer lower latency, smaller payloads, and access to streaming RPCs not exposed over HTTP/JSON. Authentication is via Mutual TLS (mTLS) on both. Here’s a sample FindBestOffers call over gRPC — returning the lowest-priced offer per property near a point of interest, for a given stay:

grpcurl -protoset descriptor_set.desc \
  -key /path/to/private.key \
  -cert /path/to/cert.pem \
  -d '{
      "request": {
          "criteria": {
              "radius": {
                  "coordinates": {
                      "latitude": 30.267153,
                      "longitude": -97.743057
                  }
              },
              "stay": {
                  "check_in": "2026-08-25",
                  "check_out": "2026-08-26",
                  "room_count": 1,
                  "guest_count": 2
              }
          },
          "page_size": 3
      }
  }' \
  partner-api.engine.com:443 \
  engine.shop.lodging.api.v1.LodgingShoppingService.FindBestOffers

{
  "offers": [
    {
      "property": {
        "property": {
          "id": "P0000000000000108984",
          "name": "Hampton Inn & Suites Austin @ The University / Capitol",
          "physicalAddress": {
            "addressLine": ["1701 Lavaca St"],
            "locality": "Austin",
            "administrativeArea": "TX",
            "postalCode": "78701",
            "countryCode": "US"
          },
          "coordinates": { "latitude": 30.279406792164, "longitude": -97.740873555225 },
          "starRating": "2.50",
          "checkInTime": "16:00",
          "checkOutTime": "12:00"
        },
        "distance": { "value": 0.2323158267289017 }
      },
      "bestOffer": {
        "continuationToken": "v0_wV4DE3rLvChwvmQSAQdArCJLITEp...",
        "bestOffer": {
          "propertyId": "P0000000000000108984",
          "price": { "price": { "total": { "currencyCode": "USD", "value": "[hidden]" } } },
          "offerAmenities": {
            "freeBreakfast": "AMENITY_AVAILABILITY_UNAVAILABLE",
            "freeParking": "AMENITY_AVAILABILITY_UNAVAILABLE"
          },
          "conditions": {
            "cancelConditions": [
              { "afterTimestamp": "2026-05-05T23:59:00-05:00", "isAllowed": true }
            ]
          }
        },
        "isRefundableAvailable": true,
        "isLoyaltyAvailable": true,
        "isFreeBreakfastAvailable": true
      }
    }
  ]
}

Next step: choose your integration path

The Omni API offers two integration approaches, depending on how much of the booking experience you want to build yourself:

Omni Swift — Turnkey deep linking. You build the discovery experience, then redirect customers to a co-branded Engine checkout. Engine handles payment, confirmation, cancellations, and post-booking support. Fastest time to market.
Omni Halo — Full API integration. Build shopping, checkout, payments, and management entirely within your platform via gRPC or HTTP/JSON. Complete control over every screen.

Not sure which path is right? See the side-by-side comparison on Integration paths, or contact omni-partnerships@engine.com.