Sound Transit

Sound Transit is a regional transit authority serving the Seattle-Puget Sound area of Washington State, operating light rail, commuter rail, and express bus services. The Sound Transit Open Transit Data (OTD) program provides GTFS static and real-time data feeds, OneBusAway API access, and GTFS-RT service alerts for transit application developers and researchers.

Sound Transit publishes 7 APIs on the APIs.io network, including Agencies API, Arrivals And Departures API, Routes API, and 4 more. Tagged areas include Transit, Transportation, GTFS, Real-Time, and Public Transit.

The Sound Transit catalog on APIs.io includes 1 JSON-LD context and 2 Spectral governance rulesets.

Sound Transit’s developer surface includes developer portal, support, and 14 more developer resources.

🌐 Visit website 📡 Source on GitHub

37.0/100 thin ▬ flat Agent 20/100 agent aware saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

AccessFreemium

1 APIs

Transit Transportation GTFS Real-Time Public Transit Government Seattle

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 37.0/100 · thin

Contract Quality 12.2 / 21

Developer Ergonomics 5.3 / 17

Access Clarity 4.9 / 17

Operational Transparency 1.2 / 11

Contract Governance 1.4 / 10

Discoverability 5.8 / 9

Regulatory Posture 4.2 / 15

Agent readiness — 20/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 9 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 4 / 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 Government & Public Sector 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 does not apply to this provider. The published contracts declare no write operations, and a read-only API cannot create-or-update. The facet is excluded from this provider's denominator entirely — not scored zero. A reference or data API is not deficient for being unable to upsert.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% 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/sound-transit: 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 →

APIs 7

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

Sound Transit Agencies API

Transit agency information and coverage

Sound Transit Arrivals And Departures API

Real-time and scheduled arrival/departure information

Sound Transit Routes API

Route definitions and schedules

Sound Transit Stops API

Stop locations and schedules

Sound Transit System API

System utilities and configuration

Sound Transit Trips API

Trip details and active vehicle positions

Sound Transit Vehicles API

Active vehicle locations and assignments

Scroll for all 7

Open Collections 9

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

API Collection

OPEN COLLECTION

Sound Transit OneBusAway Agencies API

OPEN COLLECTION

Sound Transit OneBusAway Agencies Arrivals And Departures API

OPEN COLLECTION

Sound Transit OneBusAway API

OPEN COLLECTION

Sound Transit OneBusAway Agencies Routes API

OPEN COLLECTION

Sound Transit OneBusAway Agencies Stops API

OPEN COLLECTION

Sound Transit OneBusAway Agencies System API

OPEN COLLECTION

Sound Transit OneBusAway Agencies Trips API

OPEN COLLECTION

Sound Transit OneBusAway Agencies Vehicles API

OPEN COLLECTION

Scroll for all 9

Pricing Plans 1

Published pricing tiers and plan structures.

Sound Transit Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Sound Transit Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Sound Transit Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Sound Transit Context

7 classes · 15 properties

JSON-LD

Spectral Rules 2

Spectral governance rulesets for linting and validating these APIs.

Sound Transit API Rules

5 rules · 3 warnings 2 info

SPECTRAL

Sound Transit API Rules

10 rules · 2 errors 7 warnings 1 info

SPECTRAL

JSON Schema 2

Standalone JSON Schema definitions for this provider's data models.

Sound Transit Arrival And Departure

14 properties

JSON SCHEMA

Sound Transit Stop

9 properties

JSON SCHEMA

JSON Structure 1

JSON Structure definitions describing this provider's data shapes.

Sound Transit Arrivals Structure

0 properties

JSON STRUCTURE

Examples 1

Example request and response payloads for these APIs.

Sound Transit Get Arrivals Example

2 fields

EXAMPLE

Security Posture 1

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

Sound Transit Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

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

Sound Transit Agentic Access

20 operations

20 operations · 0 acting

AGENTIC

Resources

Get Started 1

Portal, sign-up, and the first successful call

Portal

Portal

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

API Key Request

API Key Request

Operate 1

Status, limits, changes, and where to get help

Support

Support

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

Trip Planner

Trip Planner

Company 2

The organization behind the API

LinkedIn

Website

Website

Other 6

Properties that don't map to a standard resource type

GTFS Static Feeds

GTFS Static Feeds

GTFS-RT Service Alerts (Protocol Buffers)

GTFS-RT Service Alerts (Protocol Buffers)

GTFS-RT Service Alerts (JSON)

GTFS-RT Service Alerts (JSON)

Transitland Feed

Transitland Feed

OneBusAway

OneBusAway

Real-Time Coverage

Real-Time Coverage

Source (apis.yml)

aid: sound-transit
name: Sound Transit
description: Sound Transit is a regional transit authority serving the Seattle-Puget Sound area of Washington State, operating
  light rail, commuter rail, and express bus services. The Sound Transit Open Transit Data (OTD) program provides GTFS static
  and real-time data feeds, OneBusAway API access, and GTFS-RT service alerts for transit application developers and researchers.
type: Index
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
position: Consuming
access: 3rd-Party
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/sound-transit.png
tags:
- Transit
- Transportation
- GTFS
- Real-Time
- Public Transit
- Government
- Seattle
created: '2026-03-16'
modified: '2026-05-19'
url: https://raw.githubusercontent.com/api-evangelist/sound-transit/refs/heads/main/apis.yml
specificationVersion: '0.23'
apis:
- aid: sound-transit:sound-transit-agencies-api
  name: Sound Transit Agencies API
  description: Transit agency information and coverage
  humanURL: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  baseURL: https://api.pugetsound.onebusaway.org/api/where
  tags:
  - Agencies
  properties:
  - type: OpenAPI
    url: openapi/sound-transit-agencies-api-openapi.yml
  - type: Documentation
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  - type: Reference
    url: http://developer.onebusaway.org/
  - type: GTFS Downloads
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/otd-downloads
- aid: sound-transit:sound-transit-arrivals-and-departures-api
  name: Sound Transit Arrivals And Departures API
  description: Real-time and scheduled arrival/departure information
  humanURL: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  baseURL: https://api.pugetsound.onebusaway.org/api/where
  tags:
  - Arrivals And Departures
  properties:
  - type: OpenAPI
    url: openapi/sound-transit-arrivals-and-departures-api-openapi.yml
  - type: Documentation
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  - type: Reference
    url: http://developer.onebusaway.org/
  - type: GTFS Downloads
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/otd-downloads
- aid: sound-transit:sound-transit-routes-api
  name: Sound Transit Routes API
  description: Route definitions and schedules
  humanURL: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  baseURL: https://api.pugetsound.onebusaway.org/api/where
  tags:
  - Routes
  properties:
  - type: OpenAPI
    url: openapi/sound-transit-routes-api-openapi.yml
  - type: Documentation
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  - type: Reference
    url: http://developer.onebusaway.org/
  - type: GTFS Downloads
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/otd-downloads
- aid: sound-transit:sound-transit-stops-api
  name: Sound Transit Stops API
  description: Stop locations and schedules
  humanURL: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  baseURL: https://api.pugetsound.onebusaway.org/api/where
  tags:
  - Stops
  properties:
  - type: OpenAPI
    url: openapi/sound-transit-stops-api-openapi.yml
  - type: Documentation
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  - type: Reference
    url: http://developer.onebusaway.org/
  - type: GTFS Downloads
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/otd-downloads
- aid: sound-transit:sound-transit-system-api
  name: Sound Transit System API
  description: System utilities and configuration
  humanURL: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  baseURL: https://api.pugetsound.onebusaway.org/api/where
  tags:
  - System
  properties:
  - type: OpenAPI
    url: openapi/sound-transit-system-api-openapi.yml
  - type: Documentation
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  - type: Reference
    url: http://developer.onebusaway.org/
  - type: GTFS Downloads
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/otd-downloads
- aid: sound-transit:sound-transit-trips-api
  name: Sound Transit Trips API
  description: Trip details and active vehicle positions
  humanURL: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  baseURL: https://api.pugetsound.onebusaway.org/api/where
  tags:
  - Trips
  properties:
  - type: OpenAPI
    url: openapi/sound-transit-trips-api-openapi.yml
  - type: Documentation
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  - type: Reference
    url: http://developer.onebusaway.org/
  - type: GTFS Downloads
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/otd-downloads
- aid: sound-transit:sound-transit-vehicles-api
  name: Sound Transit Vehicles API
  description: Active vehicle locations and assignments
  humanURL: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  baseURL: https://api.pugetsound.onebusaway.org/api/where
  tags:
  - Vehicles
  properties:
  - type: OpenAPI
    url: openapi/sound-transit-vehicles-api-openapi.yml
  - type: Documentation
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
  - type: Reference
    url: http://developer.onebusaway.org/
  - type: GTFS Downloads
    url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/otd-downloads
common:
- type: AgenticAccess
  url: agentic-access/sound-transit-agentic-access.yml
- type: DomainSecurity
  url: security/sound-transit-domain-security.yml
- type: GitHubOrganization
  url: https://github.com/SoundTransit
- type: LinkedIn
  url: https://www.linkedin.com/company/sound-transit
- type: Portal
  url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
- type: Website
  url: https://www.soundtransit.org/
- type: GTFS Static Feeds
  url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/otd-downloads
- type: GTFS-RT Service Alerts (Protocol Buffers)
  url: https://s3.amazonaws.com/st-service-alerts-prod/alerts.pb
- type: GTFS-RT Service Alerts (JSON)
  url: https://s3.amazonaws.com/st-service-alerts-prod/alerts_pb.json
- type: Transitland Feed
  url: https://www.transit.land/feeds/f-c23-soundtransit
- type: OneBusAway
  url: https://onebusaway.org/
- type: TermsOfService
  url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd/transit-data-terms-use
- type: API Key Request
  url: mailto:oba_api_key@soundtransit.org
- type: Support
  url: mailto:open_transit_data@soundtransit.org
- type: Trip Planner
  url: https://tripplanner.kingcounty.gov/
- type: Real-Time Coverage
  url: https://www.soundtransit.org/help-contacts/business-information/open-transit-data-otd
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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