LittleHorse

LittleHorse is an open source workflow engine for orchestrating distributed systems with support for Java, Go, Python, and .NET.

LittleHorse publishes 6 API contracts indexed on the APIs.io network, including External Events API, Node Runs API, Task Definitions API, and 3 more. Tagged areas include Microservices.

The LittleHorse catalog on APIs.io includes 1 Spectral governance ruleset.

LittleHorse’s developer surface includes engineering blog and 8 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

18.5/100 emerging ▬ flat Agent 17/100 agent aware Front door AI 5/6 prominent Heartbeat 68/100 alive Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

AccessFreemium

1 published contract

Microservices

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 18.5/100 · emerging

Contract Quality 7.8 / 19

Developer Ergonomics 0.4 / 15

Access Clarity 1.0 / 15

Operational Transparency 1.2 / 10

Contract Governance 1.2 / 9

Discoverability 2.9 / 8

Regulatory Posture 0.0 / 15

Create-or-Update Ergonomics 2.2 / 10

Agent readiness — 17/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 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 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

Pagination 0 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) 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/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship Ask about this →
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey) Ask about this →
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented) Ask about this →
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes Ask about this →
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link Ask about this →

11 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Developer Ergonomics scores 2.4 — up to +19.5 composite points Ask about this →
Access Clarity scores 6.4 — up to +18.7 composite points Ask about this →
Contract Quality scores 41.6 — up to +14.6 composite points Ask about this →

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Not sure how this applies to your stack? Ask about any one item. Kin Lane reads every question, looks at your profile and your situation, and replies with what a fix would take — scoped to that one area, priced up front, yours whether you ship it or not. Ask a question →

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 the provider profile at artifacts.apis.io/littlehorse/apis.yml: open an issue on github.com/api-evangelist/littlehorse to ask a question or point us at an artifact you publish. 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
Artifact Hub Cloud-Native Packages	undeclared	-	-	-

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.

OpenAPI

measured — observed by APIs.io (published)

APIs 6

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

LittleHorse External Events API

The External Events API from LittleHorse — 3 operation(s) for external events.

LittleHorse Node Runs API

The Node Runs API from LittleHorse — 1 operation(s) for node runs.

LittleHorse Task Definitions API

The Task Definitions API from LittleHorse — 2 operation(s) for task definitions.

LittleHorse User Tasks API

The User Tasks API from LittleHorse — 3 operation(s) for user tasks.

LittleHorse Workflow Runs API

The Workflow Runs API from LittleHorse — 5 operation(s) for workflow runs.

LittleHorse Workflow Specs API

The Workflow Specs API from LittleHorse — 2 operation(s) for workflow specs.

Open Collections 7

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

LittleHorse REST API

OPEN COLLECTION

LittleHorse REST External Events API

OPEN COLLECTION

LittleHorse REST External Events Node Runs API

OPEN COLLECTION

LittleHorse REST External Events Task Definitions API

OPEN COLLECTION

LittleHorse REST External Events User Tasks API

OPEN COLLECTION

LittleHorse REST External Events Workflow Runs API

OPEN COLLECTION

LittleHorse REST External Events Workflow Specs API

OPEN COLLECTION

Scroll for all 7

LittleHorse API pricing

Not yet checked against LittleHorse's own pricing page. Compiled by API Evangelist on 2026-05-04; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Free freemium	Free
Professional paid	Free
Enterprise enterprise	—

Plan details, limits and sources →

Rate limits

Free Tier Default: 10 requests per minute
Free Tier Monthly Quota: 1000 requests per month
Professional Tier Default: 100 requests per minute

Compiled by API Evangelist, not yet checked against LittleHorse's documentation. All 5 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

LittleHorse Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

LittleHorse Rate Limits

5 limits

RATE LIMITS

FinOps 1

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

LittleHorse Finops

FINOPS

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs. Counts are the severity each rule declares, not results of running them.

LittleHorse API Rules

54 rules · 52 error-severity 1 warn-severity 1 info-severity

SPECTRAL

Security Posture 1

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

LittleHorse Domain Security

TLSv1.3 · HSTS

SECURITY

Agentic Access (API Evangelist recommendations) 1

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

LittleHorse Agentic Access

22 operations · 12 acting · 1 human-in-the-loop

22 operations · 12 acting

AGENTIC

Resources

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 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

RateLimits

RateLimits

Commercial 2

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Source (apis.yml)

aid: littlehorse
name: LittleHorse
description: LittleHorse is an open source workflow engine for orchestrating distributed systems with support for Java, Go,
  Python, and .NET.
type: Index
deliveryModel:
  model: unknown
  open_source: false
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - openapi
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: low
  source:
  - plans
  - security
  generated: '2026-11-13'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/littlehorse.png
tags:
- Microservices
url: https://raw.githubusercontent.com/api-evangelist/littlehorse/refs/heads/main/apis.yml
created: '2026-03-26'
modified: '2026-05-19'
specificationVersion: '0.23'
apis:
- aid: littlehorse:littlehorse-external-events-api
  name: LittleHorse External Events API
  description: The External Events API from LittleHorse — 3 operation(s) for external events.
  humanURL: https://littlehorse.dev/
  tags:
  - external-events
  tags_raw:
  - External Events
  properties:
  - type: OpenAPI
    url: openapi/littlehorse-external-events-api-openapi.yml
- aid: littlehorse:littlehorse-node-runs-api
  name: LittleHorse Node Runs API
  description: The Node Runs API from LittleHorse — 1 operation(s) for node runs.
  humanURL: https://littlehorse.dev/
  tags:
  - Node Runs
  properties:
  - type: OpenAPI
    url: openapi/littlehorse-node-runs-api-openapi.yml
- aid: littlehorse:littlehorse-task-definitions-api
  name: LittleHorse Task Definitions API
  description: The Task Definitions API from LittleHorse — 2 operation(s) for task definitions.
  humanURL: https://littlehorse.dev/
  tags:
  - Task Definitions
  properties:
  - type: OpenAPI
    url: openapi/littlehorse-task-definitions-api-openapi.yml
- aid: littlehorse:littlehorse-user-tasks-api
  name: LittleHorse User Tasks API
  description: The User Tasks API from LittleHorse — 3 operation(s) for user tasks.
  humanURL: https://littlehorse.dev/
  tags:
  - User Tasks
  properties:
  - type: OpenAPI
    url: openapi/littlehorse-user-tasks-api-openapi.yml
- aid: littlehorse:littlehorse-workflow-runs-api
  name: LittleHorse Workflow Runs API
  description: The Workflow Runs API from LittleHorse — 5 operation(s) for workflow runs.
  humanURL: https://littlehorse.dev/
  tags:
  - Workflow Runs
  properties:
  - type: OpenAPI
    url: openapi/littlehorse-workflow-runs-api-openapi.yml
- aid: littlehorse:littlehorse-workflow-specs-api
  name: LittleHorse Workflow Specs API
  description: The Workflow Specs API from LittleHorse — 2 operation(s) for workflow specs.
  humanURL: https://littlehorse.dev/
  tags:
  - Workflow Specs
  properties:
  - type: OpenAPI
    url: openapi/littlehorse-workflow-specs-api-openapi.yml
common:
- type: Plans
  url: plans/littlehorse-plans-pricing.yml
- type: RateLimits
  url: rate-limits/littlehorse-rate-limits.yml
- type: FinOps
  url: finops/littlehorse-finops.yml
- type: AgenticAccess
  url: agentic-access/littlehorse-agentic-access.yml
- type: DomainSecurity
  url: security/littlehorse-domain-security.yml
- type: GitHubOrganization
  url: https://github.com/littlehorse-enterprises
- type: LinkedIn
  url: https://www.linkedin.com/company/littlehorse
- type: Website
  url: https://littlehorse.dev/
- url: https://littlehorse.dev/blog/rss.xml
  type: Blog
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

LittleHorse API — frequently asked questions

Does LittleHorse have an API?

Yes. APIs.io lists 6 APIs from LittleHorse, including LittleHorse External Events API, LittleHorse Node Runs API and LittleHorse Task Definitions API, and 3 more.

Is there an OpenAPI specification for the LittleHorse API?

Yes. APIs.io indexes 6 OpenAPI specifications for LittleHorse, each linked for download from this page.

How much does the LittleHorse API cost?

APIs.io lists 3 pricing plans for LittleHorse, with each plan's price, limits and inclusions under Pricing on this page.

Is the LittleHorse API ready for AI agents?

LittleHorse has a Kin Score of 18.5 out of 100 (emerging) and an Agent Readiness score of 16.6 (agent-aware), scored by API Evangelist on 2026-11-13.

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

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https://apis.io/mcp

Tools for providers

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find_providersBrowse and filter every provider in the catalog.
get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

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