Fabraix

Fabraix builds red-teaming AI agents that continuously find security vulnerabilities in customer-facing AI systems. Its flagship product, Nyx, autonomously discovers exploits across chat, voice, browser, and coding agents without needing source-code access, drawing on a library of more than 10,000 jailbreaks and adaptive attack strategies that pursue promising approaches across hundreds of interactions. Fabraix also created ACE (Adversarial Cost to Exploit), a game-theoretic benchmark that measures AI security by the cost of a successful attack, enabling continuous, lower-cost vulnerability testing that re-assesses systems with each update. Fabraix is a Y Combinator (Summer 2026) company. This profile is maintained by the API Evangelist network; no public API, developer documentation, or machine-readable surface has been published by Fabraix at this time.

Fabraix is profiled on the APIs.io network. Tagged areas include Company, AI Security, Red Teaming, AI Agents, and Adversarial Verification.

🌐 Visit website 📡 Source on GitHub

5.0/100 minimal ▬ flat Agent 0/100 human only Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

0 APIs

Company AI Security Red Teaming AI AgentsAdversarial VerificationCybersecurity LLM Security Y Combinator

Kin Score

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

Composite quality — 5.0/100 · minimal

Contract Quality 0.0 / 25

Developer Ergonomics 0.0 / 20

Access Clarity 0.0 / 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.

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Resources

Company 1

The organization behind the API

Website

Website

Other 2

Properties that don't map to a standard resource type

CompanyProfile

CompanyProfile

Source (apis.yml)

aid: fabraix
name: Fabraix
description: Fabraix builds red-teaming AI agents that continuously find security vulnerabilities in customer-facing AI systems.
  Its flagship product, Nyx, autonomously discovers exploits across chat, voice, browser, and coding agents without needing
  source-code access, drawing on a library of more than 10,000 jailbreaks and adaptive attack strategies that pursue promising
  approaches across hundreds of interactions. Fabraix also created ACE (Adversarial Cost to Exploit), a game-theoretic benchmark
  that measures AI security by the cost of a successful attack, enabling continuous, lower-cost vulnerability testing that
  re-assesses systems with each update. Fabraix is a Y Combinator (Summer 2026) company. This profile is maintained by the
  API Evangelist network; no public API, developer documentation, or machine-readable surface has been published by Fabraix
  at this time.
url: https://raw.githubusercontent.com/api-evangelist/fabraix/refs/heads/main/apis.yml
deliveryModel:
  model: unknown
  open_source: false
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - none
  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://fabraix.com/og.png
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
x-tier: stub
x-tier-reason: portfolio-lead
x-batch: Summer 2026
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- AI Security
- Red Teaming
- AI Agents
- Adversarial Verification
- Cybersecurity
- LLM Security
- Y Combinator
apis: []
common:
- type: Website
  url: https://fabraix.com
- type: X
  url: https://x.com/fabraixhq
- type: CompanyProfile
  url: https://www.ycombinator.com/companies/fabraix
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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