Engine

Engine (formerly Hotel Engine, rebranded in 2024) is a Denver, Colorado business travel and spend platform for booking and managing lodging, flights, rental cars, group travel, and meeting and event spaces, with travel policy enforcement, trip approvals, consolidated DirectBill invoicing, and the Engine X charge card. Engine says it serves 25,000+ businesses and 1.2 million travelers with negotiated rates across 1,000,000+ hotel properties. Its API product is Omni — a partner-facing lodging inventory API offered over gRPC and HTTP/JSON, authenticated with mutual TLS, that covers property content, real-time rate shopping, booking, folio generation, and cancellation. Omni is protobuf-first: the proto contracts are published under Apache 2.0 on GitHub and the Swagger document, descriptor set, and JVM client bindings are generated from them and released per version.

Engine publishes 4 API contracts indexed on the APIs.io network, including Catalog Service API, Lodging Booking Service API, Lodging Shopping Service API, and 1 more. Tagged areas include Company, Travel, Business Travel, Lodging, and Hotels.

Engine’s developer surface includes documentation, API reference, getting-started guide, support, engineering blog, pricing, signup flow, and 27 more developer resources.

🌐 Visit website 📡 Source on GitHub

53.0/100 developing ▬ flat Agent 26/100 agent aware Front door AI 1/6 silent open core · Apache-2.0 Full breakdown ↓
scored 2026-10-17 · rubric v0.24.0

AccessApproval

2 published contracts

Company Travel Business Travel Lodging Hotels Booking Travel Management Expense Management Payments gRPC Protobuf Partner API

Kin Score

Kin Score How this is scored →
scored 2026-10-17 · rubric v0.24.0

Composite quality — 53.0/100 · developing

Contract Quality 7.9 / 19

Developer Ergonomics 11.0 / 15

Access Clarity 7.9 / 15

Operational Transparency 6.7 / 10

Contract Governance 0.4 / 9

Discoverability 5.5 / 8

Regulatory Posture 4.2 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 26/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Payments regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/hotel-engine: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Travel and Airline Distribution	builds-on	17.2 (thin)	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

gRPC

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

APIs 4

Individual APIs this provider publishes, each with its own machine-readable definition.

Engine Catalog Service API

The CatalogService API from Engine — 1 operation(s) for catalogservice.

Engine Lodging Booking Service API

The LodgingBookingService API from Engine — 5 operation(s) for lodgingbookingservice.

Engine Lodging Shopping Service API

The LodgingShoppingService API from Engine — 2 operation(s) for lodgingshoppingservice.

Engine Content Service API

The Content Service API from Engine — 2 operation(s) for content service.

Open Collections 5

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

Omni, Powered by Engine Catalog Service API

OPEN COLLECTION

Omni, Powered by Engine Content Service API

OPEN COLLECTION

Omni, Powered by Engine Lodging Booking Service API

OPEN COLLECTION

Omni, Powered by Engine Lodging Shopping Service API

OPEN COLLECTION

Rate Limits 1

Documented rate limits and quota policies.

Hotel Engine Rate Limits

16 limits

RATE LIMITS

OpenAPI Overlays 1

Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.

Hotel Engine Omni Partner Api Overlay

9 actions · update · hotel-engine-omni-partner-api-openapi.yml

GENERATED

Security Posture 4

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Hotel Engine Authentication

mutualTLS · 1 scheme

SECURITY

Hotel Engine Domain Security

TLSv1.3 · DNSSEC · DMARC

SECURITY

Hotel Engine Vulnerability Disclosure

Hackerone · contact published

SECURITY

Hotel Engine Trust Center

SOC 2 Type II

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Hotel Engine Agentic Access

11 operations · 7 acting

AGENTIC

Resources

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal

GettingStarted

SignUp

Sandbox

Documentation 3

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

APIReference

APIReference

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

AgentSkill

AgentSkill

LLMsTxt

LLMsTxt

AgenticAccess

AgenticAccess

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

Lifecycle

Lifecycle

Conformance

Conformance

Build 4

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

SourceCode

Packages

SDKs

Access & Security 5

Authentication, authorization, and security posture

Security

Security

VulnerabilityDisclosure

VulnerabilityDisclosure

TrustCenter

TrustCenter

Compliance

Compliance

DomainSecurity

DomainSecurity

Operate 6

Status, limits, changes, and where to get help

RateLimits

Support

HelpCenter

ChangeLog

ChangeLog

Deprecation

Commercial 4

Pricing, plans, and the legal terms of use

License

Pricing

TermsOfService

PrivacyPolicy

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: hotel-engine
name: Engine
description: 'Engine (formerly Hotel Engine, rebranded in 2024) is a Denver, Colorado business travel and spend platform for
  booking and managing lodging, flights, rental cars, group travel, and meeting and event spaces, with travel policy enforcement,
  trip approvals, consolidated DirectBill invoicing, and the Engine X charge card. Engine says it serves 25,000+ businesses
  and 1.2 million travelers with negotiated rates across 1,000,000+ hotel properties. Its API product is Omni — a partner-facing
  lodging inventory API offered over gRPC and HTTP/JSON, authenticated with mutual TLS, that covers property content, real-time
  rate shopping, booking, folio generation, and cancellation. Omni is protobuf-first: the proto contracts are published under
  Apache 2.0 on GitHub and the Swagger document, descriptor set, and JVM client bindings are generated from them and released
  per version.'
deliveryModel:
  model: open-core
  license: Apache-2.0
  open_source: true
  commercial: true
  callable_host: true
  label: Open core · an OSS project plus a commercial hosted product
  confidence: high
  source:
  - license
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: approval
  trial: false
  try_now: false
  public: false
  label: Requires approval
  confidence: medium
  source:
  - authentication
  - rate-limits
  - security
  - sandbox
  generated: '2026-09-02'
  method: derived
image: https://engine.com/_astro/engine-og-default.BAjJjAAC.png
url: https://raw.githubusercontent.com/api-evangelist/hotel-engine/refs/heads/main/apis.yml
x-type: company
x-source: harvest:secondary-market
x-source-url: https://forgeglobal.com/hotel-engine_stock/
x-tier: profiled
x-tier-reason: enrichment
specificationVersion: '0.23'
created: '2026-08-04'
modified: '2026-08-04'
tags:
- Company
- Travel
- Business Travel
- Lodging
- Hotels
- Booking
- Travel Management
- Expense Management
- Payments
- gRPC
- Protobuf
- Partner API
apis:
- aid: hotel-engine:hotel-engine-catalogservice-api
  name: Engine Catalog Service API
  description: The CatalogService API from Engine — 1 operation(s) for catalogservice.
  humanURL: https://engine-public.github.io/engine-partner-api/
  baseURL: https://partner-api.engine.com
  tags:
  - CatalogService
  properties:
  - type: OpenAPI
    url: openapi/hotel-engine-catalogservice-api-openapi.yml
  - type: Protobuf
    url: grpc/_index.yml
  - type: Authentication
    url: authentication/hotel-engine-authentication.yml
  - type: Conventions
    url: conventions/hotel-engine-conventions.yml
  - type: ErrorCatalog
    url: errors/hotel-engine-problem-types.yml
  - type: DataModel
    url: data-model/hotel-engine-data-model.yml
  - type: RateLimits
    url: rate-limits/hotel-engine-rate-limits.yml
  - type: X-MCPServerCandidate
    url: mcp/hotel-engine-mcp.yml
    note: 'Renamed from MCPServer 2026-09-03 (roadmap#247): the manifest self-describes as status: candidate — a tool list
      derived from the published API contracts, not an existing server. The scorer already read the manifest and reported
      mcp_server correctly; the MCPServer type was crediting the artifact-type surfaces with a server that does not exist.'
  - type: Documentation
    url: https://engine-public.github.io/engine-partner-api/
  - type: APIReference
    url: https://engine-public.github.io/engine-partner-api/swagger-ui/index.html
  - type: GettingStarted
    url: https://engine-public.github.io/engine-partner-api/getting-started.html
- aid: hotel-engine:hotel-engine-lodgingbookingservice-api
  name: Engine Lodging Booking Service API
  description: The LodgingBookingService API from Engine — 5 operation(s) for lodgingbookingservice.
  humanURL: https://engine-public.github.io/engine-partner-api/
  baseURL: https://partner-api.engine.com
  tags:
  - LodgingBookingService
  properties:
  - type: OpenAPI
    url: openapi/hotel-engine-lodgingbookingservice-api-openapi.yml
  - type: Protobuf
    url: grpc/_index.yml
  - type: Authentication
    url: authentication/hotel-engine-authentication.yml
  - type: Conventions
    url: conventions/hotel-engine-conventions.yml
  - type: ErrorCatalog
    url: errors/hotel-engine-problem-types.yml
  - type: DataModel
    url: data-model/hotel-engine-data-model.yml
  - type: RateLimits
    url: rate-limits/hotel-engine-rate-limits.yml
  - type: Documentation
    url: https://engine-public.github.io/engine-partner-api/
  - type: APIReference
    url: https://engine-public.github.io/engine-partner-api/swagger-ui/index.html
  - type: GettingStarted
    url: https://engine-public.github.io/engine-partner-api/getting-started.html
- aid: hotel-engine:hotel-engine-lodgingshoppingservice-api
  name: Engine Lodging Shopping Service API
  description: The LodgingShoppingService API from Engine — 2 operation(s) for lodgingshoppingservice.
  humanURL: https://engine-public.github.io/engine-partner-api/
  baseURL: https://partner-api.engine.com
  tags:
  - LodgingShoppingService
  properties:
  - type: OpenAPI
    url: openapi/hotel-engine-lodgingshoppingservice-api-openapi.yml
  - type: Protobuf
    url: grpc/_index.yml
  - type: Authentication
    url: authentication/hotel-engine-authentication.yml
  - type: Conventions
    url: conventions/hotel-engine-conventions.yml
  - type: ErrorCatalog
    url: errors/hotel-engine-problem-types.yml
  - type: DataModel
    url: data-model/hotel-engine-data-model.yml
  - type: RateLimits
    url: rate-limits/hotel-engine-rate-limits.yml
  - type: Documentation
    url: https://engine-public.github.io/engine-partner-api/
  - type: APIReference
    url: https://engine-public.github.io/engine-partner-api/swagger-ui/index.html
  - type: GettingStarted
    url: https://engine-public.github.io/engine-partner-api/getting-started.html
- aid: hotel-engine:hotel-engine-content-service-api
  name: Engine Content Service API
  description: The Content Service API from Engine — 2 operation(s) for content service.
  humanURL: https://engine-public.github.io/engine-partner-api/
  baseURL: https://partner-api.engine.com
  tags:
  - Content Service
  properties:
  - type: OpenAPI
    url: openapi/hotel-engine-content-service-api-openapi.yml
  - type: Protobuf
    url: grpc/_index.yml
  - type: Authentication
    url: authentication/hotel-engine-authentication.yml
  - type: Conventions
    url: conventions/hotel-engine-conventions.yml
  - type: ErrorCatalog
    url: errors/hotel-engine-problem-types.yml
  - type: DataModel
    url: data-model/hotel-engine-data-model.yml
  - type: RateLimits
    url: rate-limits/hotel-engine-rate-limits.yml
  - type: Documentation
    url: https://engine-public.github.io/engine-partner-api/
  - type: APIReference
    url: https://engine-public.github.io/engine-partner-api/swagger-ui/index.html
  - type: GettingStarted
    url: https://engine-public.github.io/engine-partner-api/getting-started.html
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: RateLimits
  url: rate-limits/hotel-engine-rate-limits.yml
- type: Overlay
  url: overlays/hotel-engine-omni-partner-api-overlay.yaml
- type: License
  name: Apache-2.0
  url: https://github.com/engine-public/engine-partner-api/blob/main/LICENSE
- type: Website
  url: https://www.engine.com/
- type: DeveloperPortal
  url: https://omni.engine.com/
- type: Documentation
  url: https://engine-public.github.io/engine-partner-api/
- type: APIReference
  name: HTTP/JSON reference (Swagger UI)
  url: https://engine-public.github.io/engine-partner-api/swagger-ui/index.html
- type: APIReference
  name: gRPC reference
  url: https://engine-public.github.io/engine-partner-api/api/grpc/index.html
- type: GettingStarted
  url: https://engine-public.github.io/engine-partner-api/getting-started.html
- type: Support
  url: https://engine-public.github.io/engine-partner-api/support.html
- type: HelpCenter
  url: https://www.engine.com/faqs
- type: Blog
  url: https://www.engine.com/blog
- type: GitHubOrganization
  url: https://github.com/engine-public
- type: SourceCode
  url: https://github.com/engine-public/engine-partner-api
- type: Pricing
  url: https://www.engine.com/pricing
- type: SignUp
  url: https://www.engine.com/sign-up
- type: TermsOfService
  url: https://www.engine.com/terms-of-service
- type: PrivacyPolicy
  url: https://www.engine.com/privacy-policy
- type: ChangeLog
  url: https://github.com/engine-public/engine-partner-api/releases
- type: ChangeLog
  name: Structured changelog
  url: changelog/hotel-engine-changelog.yml
- type: Deprecation
  url: https://engine-public.github.io/engine-partner-api/versioning.html#support-for-deprecated-versions
- type: Lifecycle
  url: lifecycle/hotel-engine-lifecycle.yml
- type: Security
  url: https://www.engine.com/responsible-disclosure
- type: VulnerabilityDisclosure
  url: security/hotel-engine-vulnerability-disclosure.yml
- type: TrustCenter
  url: https://trust.engine.com/
- type: Compliance
  url: security/hotel-engine-trust-center.yml
- type: Conformance
  url: conformance/hotel-engine-conformance.yml
- type: Packages
  url: packages/hotel-engine-packages.yml
- type: SDKs
  url: packages/hotel-engine-packages.yml
- type: Sandbox
  url: sandbox/hotel-engine-sandbox.yml
- type: AgentSkill
  url: skills/_index.yml
- type: LLMsTxt
  url: llms/hotel-engine-llms.txt
- type: AgenticAccess
  url: agentic-access/hotel-engine-agentic-access.yml
- type: DomainSecurity
  url: security/hotel-engine-domain-security.yml
x-enrichment:
  date: '2026-08-04'
  status: enriched
  artifacts_added: 74
  pass: local-v1

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