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, Neuro-Symbolic AI, Large Language Models, and Knowledge Graphs.

Extensity’s developer surface includes documentation, support, and 11 more developer resources.

🌐 Visit website 📡 Source on GitHub

12.4/100 emerging ▬ flat Agent 4/100 human only Full breakdown ↓
scored 2026-08-20 · rubric v0.12.0

0 APIs 1 MCP Servers

CompanyArtificial IntelligenceNeuro-Symbolic AILarge Language ModelsKnowledge GraphsDeveloper ToolsOpen-SourcePythonMCP

Kin Score

Kin Score How this is scored →
scored 2026-08-20 · rubric v0.12.0

Composite quality — 12.4/100 · emerging

Contract Quality 0.0 / 25

Developer Ergonomics 4.3 / 20

Access Clarity 0.0 / 20

Operational Transparency 2.4 / 13

Contract Governance 0.0 / 12

Discoverability 5.7 / 10

Agent readiness — 4/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

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

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

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 3

Status, limits, changes, and where to get help

IssueTracker

IssueTracker

Releases

Releases

Support

Support

Commercial 1

Pricing, plans, and the legal terms of use

License

License

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: '0.23'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- Artificial Intelligence
- Neuro-Symbolic AI
- Large Language Models
- Knowledge Graphs
- Developer Tools
- Open-Source
- Python
- MCP
tags_raw:
- Company
- Artificial Intelligence
- Neurosymbolic AI
- Large Language Models
- Knowledge Graphs
- Developer Tools
- Open Source
- Python
- Model Context Protocol
apis: []
common:
- type: IssueTracker
  url: https://github.com/ExtensityAI/symbolicai/issues
- type: Releases
  url: https://github.com/ExtensityAI/symbolicai/releases
- type: License
  name: BSD-3-Clause
  url: https://github.com/ExtensityAI/symbolicai/blob/main/LICENSE
- 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