Fabraix YC Application
San Francisco
Fabraix went through Y Combinator in the Summer 2026 batch as a B2B company. Below: what the company does, who founded it, and its application to YC, reconstructed question by question in the real YC form.
- YC batch
- Summer 2026
- Industry
- B2BSecurity
- Location
- San Francisco
- Team size
- 2
- Status
- Active
- Launched
- 2026
Founders
Ahmed AlyFounder/CEO
ibrahim abduFounder/CTO
What Fabraix does
Fabraix builds state-of-the-art AI red-teaming agents that continuously detect security vulnerabilities in customer-facing AI. Our product, Nyx, has already found vulnerabilities in agents at dozens of Fortune 500 companies. On AgentHarm, the leading benchmark for offensive AI security, Nyx achieved a 78% attack success rate, compared with 67% for GPT-5.6 Sol. AI agents can change more often than teams can test them. A new model, prompt, tool, permission, or data source can change what an agent does, even when the application code stays the same. And AI is also increasing how much software companies produce and how often it changes. We built Nyx to automate the work required to red-team AI agents. It is multi modal by design and interacts with the target indirectly through controlled replicas of SaaS products and websites that we maintain, placing malicious payloads in webpages, documents, files, messages, and tool outputs to test how an agent behaves under different conditions. Nyx often finds its first vulnerability within minutes or hours rather than days or weeks. Because the work is fully automated, companies can repeat the test with every change and at a much lower cost than what a 7-figure red-teaming (and point-in-time) engagement would require. We're also the team behind ACE (Adversarial Cost to Exploit), a benchmark that measures AI security in terms of how much it costs attackers to break an AI system; providing a game-theoretic framework to understand how motivated a rational attacker would be in exploiting the system.
Fabraix's YC application, reconstructed
Y Combinator application
Fabraix, Summer 2026 batch. The real form questions, answered from public data.
- Founders2
- Company7
- Progress7
- Idea4
- Equity3
- Curious2
- Batch Preference1
Company
Fabraix
AI agents that red-team other AI for security flaws.
We're building Nyx, an AI agent that acts as an autonomous red-teamer to find vulnerabilities in customer-facing AI systems. It targets changes in models, prompts, tools, and data sources - areas that traditional security reviews can't keep up with. Nyx runs multimodal attacks by interacting through replicas of real SaaS products and web systems, planting payloads to test agent boundaries. The goal is to give companies a way to catch issues as fast as they ship changes, at a fraction of the cost of human red-teaming.
San Francisco, CA, USA. We'll stay based here after YC.
San Francisco is where AI security buyers, technical partners, and talent are concentrated. Being here lets us move fast on product and sales.
21 more answers in the full application
Founders, Progress, Idea, Equity, Curious, Batch Preference are in the full version. Create a free account to open it in YC Insights, next to every other YC batch.
Frequently Asked Questions
Is this the real Fabraix YC application?
No. Y Combinator keeps submitted applications private. This is a reconstruction: the real YC form questions, answered from Fabraix's public data (launch notes, founder backgrounds, product description). It shows how a company like Fabraix would present itself to YC, not the text they submitted.
What YC batch was Fabraix in?
Fabraix was part of the Y Combinator Summer 2026 batch.
Who founded Fabraix?
Fabraix was founded by Ahmed Aly, ibrahim abdu.
What does Fabraix do?
The world's frontier hacker of AI agents.
How do I read the full reconstructed application?
Create a free Round Funded account. The full 26-answer version of Fabraix's application, and every other YC batch, is in YC Insights.
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