Openprose

OpenProse, Inc. builds an open-source (MIT) programming language for AI sessions: standing AI jobs are declared as durable Markdown contracts (`*.prose.md` files) that state what should stay true, and the system works out how much model work it takes to keep it true. The language ships as an agent skill (`open-prose`) that runs on any compliant agent host such as Claude Code, Codex, or OpenCode, and is paired with Reactor — a deterministic harness (`@openprose/reactor` SDK plus the `@openprose/reactor-cli` `reactor` binary) whose model spend scales with surprise, not the clock: a render runs only when a node's subscribed input fingerprints move, and each commit is a content-addressed receipt with no LLM in the wake/commit decision. Contract kinds are responsibility, function, gateway, pattern, and test; Forme is the semantic dependency-injection layer that wires `### Requires` facets to `### Maintains` facets. A Y Combinator company founded in 2026 (San Francisco) with open-source traction; distributed as npm packages rather than a hosted REST API.

Openprose is profiled on the APIs.io network. Tagged areas include Company, AI Agents, Agent Orchestration, Developer Tools, and Open Source.

Openprose’s developer surface includes documentation, API reference, getting-started guide, support, changelog, CLI, and 11 more developer resources.

🌐 Visit website 📡 Source on GitHub
21.2/100 emerging ▬ flat Agent 9/100 human only Full breakdown ↓
scored 2026-07-27 · rubric v0.5
0 APIs
CompanyAI AgentsAgent OrchestrationDeveloper ToolsOpen SourceProgramming LanguageLLMWorkflow AutomationY Combinator

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 21.2/100 · emerging
Contract Quality 0.0 / 25
Developer Ergonomics 11.7 / 20
Commercial Clarity 0.0 / 20
Operational Transparency 2.7 / 13
Governance 0.0 / 12
Discoverability 6.8 / 10
Agent readiness — 9/100 · human only
Machine-Readable Contract 0 / 18
Agentic Access Contract 0 / 15
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 0 / 7
Typed Event Surface 0 / 6
Agent Skills 5 / 5
Well-Known Catalog 4 / 4
Consent & Bot Identity 0 / 3
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/openprose: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

Security Posture 1

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

Openprose Domain Security

TLSv1.3 · HSTS

SECURITY

Resources

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt
LLMsTxt
 AgentSkill
AgentSkill
 WellKnown
WellKnown

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

Lifecycle
Lifecycle

Build 4

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization
 Packages
Packages
 SDKs
SDKs
 CLI
CLI

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity
DomainSecurity

Operate 3

Status, limits, changes, and where to get help

Support
Support
 ChangeLog
ChangeLog
 ChangeLog
ChangeLog

Company 1

The organization behind the API

Website
Website

Source (apis.yml)

apis.yml Raw ↑ 
aid: openprose
name: Openprose
description: 'OpenProse, Inc. builds an open-source (MIT) programming language for AI sessions: standing AI jobs are declared
  as durable Markdown contracts (`*.prose.md` files) that state what should stay true, and the system works out how much model
  work it takes to keep it true. The language ships as an agent skill (`open-prose`) that runs on any compliant agent host
  such as Claude Code, Codex, or OpenCode, and is paired with Reactor — a deterministic harness (`@openprose/reactor` SDK
  plus the `@openprose/reactor-cli` `reactor` binary) whose model spend scales with surprise, not the clock: a render runs
  only when a node''s subscribed input fingerprints move, and each commit is a content-addressed receipt with no LLM in the
  wake/commit decision. Contract kinds are responsibility, function, gateway, pattern, and test; Forme is the semantic dependency-injection
  layer that wires `### Requires` facets to `### Maintains` facets. A Y Combinator company founded in 2026 (San Francisco)
  with open-source traction; distributed as npm packages rather than a hosted REST API.'
url: https://raw.githubusercontent.com/api-evangelist/openprose/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source: []
  generated: '2026-07-22'
  method: derived
image: https://github.com/openprose.png
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-20'
tags:
- Company
- AI Agents
- Agent Orchestration
- Developer Tools
- Open Source
- Programming Language
- LLM
- Workflow Automation
- Y Combinator
apis: []
x-enrichment:
  date: '2026-07-20'
  status: enriched
  artifacts_added: 9
  pass: local-v1
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://prose.md/
- type: DeveloperPortal
  url: https://prose.md/
- type: Documentation
  url: https://docs.prose.md/start/what-is-openprose
- type: APIReference
  url: https://docs.prose.md/sdk
- type: GettingStarted
  url: https://docs.prose.md/openprose/setup
- type: GitHubOrganization
  url: https://github.com/openprose
- type: Support
  url: https://github.com/openprose/prose/issues
- type: ChangeLog
  url: https://github.com/openprose/prose/blob/main/CHANGELOG.md
- type: LLMsTxt
  url: llms/openprose-llms.txt
- type: Packages
  url: packages/openprose-packages.yml
- type: SDKs
  url: packages/openprose-packages.yml
- type: CLI
  url: cli/openprose-cli.yml
- type: AgentSkill
  url: skills/openprose-open-prose.md
- type: Lifecycle
  url: lifecycle/openprose-lifecycle.yml
- type: ChangeLog
  name: OpenProse changelog (structured)
  url: changelog/openprose-changelog.yml
- type: WellKnown
  url: well-known/openprose-well-known.yml
- type: DomainSecurity
  url: security/openprose-domain-security.yml