Extensity

ExtensityAI is an AI research company building trustworthy, verifiable AI for enterprise environments through a neurosymbolic architecture that combines large language models with symbolic validation and knowledge-graph reasoning. Its flagship open-source framework, SymbolicAI, treats LLMs as programmable, differentiable primitives (Symbol objects) governed by Design-by-Contract validation, giving developers source-traceable, contract-enforced AI they can run on-premise with sovereign data control. The company also ships developer tooling including the ontoloom MCP server for building and exploring OWL 2 ontologies with AI agents. Backed by Lightspeed Venture Partners.

Extensity is profiled on the APIs.io network. Tagged areas include Company, Artificial Intelligence, Neurosymbolic AI, Large Language Models, and Knowledge Graphs.

Extensity’s developer surface includes documentation, support, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub

13.1/100 minimal ▬ flat Agent 12/100 human only Full breakdown ↓
scored 2026-07-27 · rubric v0.5

0 APIs 1 MCP Servers

CompanyArtificial IntelligenceNeurosymbolic AILarge Language ModelsKnowledge GraphsDeveloper ToolsOpen SourcePythonModel Context Protocol

Kin Score

Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5

Composite quality — 13.1/100 · minimal

Contract Quality 0.0 / 25

Developer Ergonomics 5.7 / 20

Commercial Clarity 0.0 / 20

Operational Transparency 0.7 / 13

Governance 0.0 / 12

Discoverability 6.8 / 10

Agent readiness — 12/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 15

MCP Server 12 / 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 0 / 5

Well-Known Catalog 0 / 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/extensity: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

MCPServer

MCPServer

LLMsTxt

LLMsTxt

Build 4

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

SourceCode

Packages

SDKs

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Support

Support

Company 1

The organization behind the API

Website

Website

Source (apis.yml)

aid: extensity
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://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/extensity.png
name: Extensity
description: ExtensityAI is an AI research company building trustworthy, verifiable AI for enterprise environments through
  a neurosymbolic architecture that combines large language models with symbolic validation and knowledge-graph reasoning.
  Its flagship open-source framework, SymbolicAI, treats LLMs as programmable, differentiable primitives (Symbol objects)
  governed by Design-by-Contract validation, giving developers source-traceable, contract-enforced AI they can run on-premise
  with sovereign data control. The company also ships developer tooling including the ontoloom MCP server for building and
  exploring OWL 2 ontologies with AI agents. Backed by Lightspeed Venture Partners.
url: https://raw.githubusercontent.com/api-evangelist/extensity/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- lightspeed-venture-partners
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- Artificial Intelligence
- Neurosymbolic AI
- Large Language Models
- Knowledge Graphs
- Developer Tools
- Open Source
- Python
- Model Context Protocol
apis: []
common:
- type: DomainSecurity
  url: security/extensity-domain-security.yml
- type: Website
  url: https://extensity.ai
- type: GitHubOrganization
  url: https://github.com/ExtensityAI
- type: Documentation
  url: https://extensityai.gitbook.io/symbolicai
- type: SourceCode
  url: https://github.com/ExtensityAI/symbolicai
- type: Support
  name: Discord Community
  url: https://discord.gg/QYMNnh9ra8
- type: Packages
  url: packages/extensity-packages.yml
- type: SDKs
  url: packages/extensity-packages.yml
- type: MCPServer
  url: mcp/extensity-mcp.yml
- type: LLMsTxt
  url: llms/extensity-llms.txt
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence