Castelion website screenshot

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
11.4/100 minimal ▬ flat Agent 0/100 human only Full breakdown ↓
scored 2026-07-27 · rubric v0.5
0 APIs
CompanyDefenseAerospaceHypersonicsManufacturingWeapons SystemsNational Security

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 11.4/100 · minimal
Contract Quality 0.0 / 25
Developer Ergonomics 0.4 / 20
Commercial Clarity 4.2 / 20
Operational Transparency 0.0 / 13
Governance 0.0 / 12
Discoverability 6.8 / 10
Agent readiness — 0/100 · 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 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/castelion: 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.

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)

apis.yml Raw ↑ 
aid: castelion
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: '0.20'
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