Castelion

Castelion is a vertically integrated defense technology company that designs, tests, and manufactures next-generation military systems, with a focus on affordable, mass-producible hypersonic strike weapons such as its Blackbeard system, built rapidly and at scale to deter future conflict. Founded by former SpaceX and defense-industry engineers, it operates manufacturing and test facilities in Torrance, CA; Rio Rancho, NM; Midland, TX; and Allen, TX. Castelion is privately held and backed by Andreessen Horowitz (a16z), General Catalyst, and Lightspeed Venture Partners. It publishes no public API, developer portal, or technical documentation; this API Evangelist profile tracks it as a company in the network.

Castelion is profiled on the APIs.io network. Tagged areas include Company, Defense, Aerospace, Hypersonics, and Manufacturing.

Castelion’s developer surface includes engineering blog and 4 more developer resources.

🌐 Visit website 📡 Source on GitHub

9.7/100 minimal ▬ flat Agent 0/100 human only saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

0 APIs

Company Defense Aerospace Hypersonics ManufacturingWeapons SystemsNational Security

Kin Score

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

Composite quality — 9.7/100 · minimal

Contract Quality 0.0 / 25

Developer Ergonomics 0.5 / 20

Access Clarity 4.2 / 20

Operational Transparency 0.0 / 13

Contract Governance 0.0 / 12

Discoverability 5.0 / 10

Agent readiness — 0/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 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 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

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

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/castelion: 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 →

Security Posture 1

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

Castelion Domain Security

TLSv1.3 · DMARC

SECURITY

Resources

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 2

The organization behind the API

Website

Website

Blog

Blog

Source (apis.yml)

aid: castelion
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - pricing
  generated: '2026-08-28'
  method: derived
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/castelion.png
name: Castelion
description: Castelion is a vertically integrated defense technology company that designs, tests, and manufactures next-generation
  military systems, with a focus on affordable, mass-producible hypersonic strike weapons such as its Blackbeard system, built
  rapidly and at scale to deter future conflict. Founded by former SpaceX and defense-industry engineers, it operates manufacturing
  and test facilities in Torrance, CA; Rio Rancho, NM; Midland, TX; and Allen, TX. Castelion is privately held and backed
  by Andreessen Horowitz (a16z), General Catalyst, and Lightspeed Venture Partners. It publishes no public API, developer
  portal, or technical documentation; this API Evangelist profile tracks it as a company in the network.
url: https://raw.githubusercontent.com/api-evangelist/castelion/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- a16z
- general-catalyst
- lightspeed-venture-partners
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-18'
tags:
- Company
- Defense
- Aerospace
- Hypersonics
- Manufacturing
- Weapons Systems
- National Security
apis: []
common:
- type: DomainSecurity
  url: security/castelion-domain-security.yml
- type: Website
  url: https://www.castelion.com/
- type: TermsOfService
  url: https://www.castelion.com/terms-conditions/
- type: PrivacyPolicy
  url: https://www.castelion.com/privacy-policy/
- type: Blog
  url: https://www.castelion.com/news/
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

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