Cosine
YC W23London, GB · Founded 2022 · 12 employees · Hiring · 2 known investors
Cosine Red Team is an AI-powered security testing platform that identifies attack paths and vulnerabilities in critical systems through automated scanning and adversarial exploitation. The platform serves enterprise customers seeking to strengthen their security posture across APIs, code, authentication systems, data flows, and infrastructure.
Also known as Buildt
AI & Machine LearningCybersecurityDeveloper ToolsEnterprise SoftwareArtificial IntelligenceGenerative AIMachine LearningNLPUnited KingdomEuropePartly Remote
Founders & leadership· Y Combinator alumni (W23)
Cosine was founded in 2022 by Alistair Pullen, Yang Li, and Sam Stenner.
AP
Alistair Pullenin𝕏CEO & Co-FounderAlistair Pullen is a full-stack software engineer with 15 years of experience in LLMs and embeddings. He previously founded Fancy, a YC S20 company acquired by Gopuff, and is currently developing an AI development tool.
YL
Yang Liin𝕏FounderYang Li held executive roles at several fintech and mobility companies, including VP of Europe at Luno (Digital Currency Group's consumer arm), founder of Ziglu (later acquired by Robinhood), and Commercial Director at Mobike (acquired by Meituan). He was recognized as part of the 2021 Forbes 30 Under 30 cohort.
SS
Sam StennerFounder
Investors · 2
Funding
SEC filings, press & company announcements$2.5M disclosed across 1 round · 2024
- $2.5MraisedAug 2024 · 3 sourcesSource ↗
Source: company announcements and press reports — follow each round's link for the claim.
The YC application· Winter 2023 batch
Competitors · 4
by search overlap
Netezza5 shared keywordsIBM is a global technology company whose business spans enterprise software (including Red Hat, HashiCorp, and Confluent), IT infrastructure such as mainframes, servers, and storage, and IT consulting services. The company is also investing heavily in quantum computing and AI-based enterprise offerings, including its Lightwell open-source software security clearinghouse and the Anderon quantum wafer foundry.
CodeSignal, Inc.5 shared keywordsCodeSignal provides an educational ebook guide for talent teams on implementing AI hiring tools, covering readiness assessment, solution selection, and compliant usage practices.
ArrowPoint4 shared keywordsCisco provides networking, data center, and security technology for enterprises, including infrastructure to run traditional and AI workloads and tools to keep organizations running against cyberattacks and outages. Its platform connects networking devices and monitors security events across corporate networks.
NVIDIA4 shared keywordsNVIDIA designs GPUs, AI computing hardware, and software platforms for AI development, data centers, autonomous vehicles, and robotics, serving developers, researchers, and enterprises. Its offerings include AI models, power architecture for AI factories, and compute infrastructure used across industries such as manufacturing, healthcare, and automotive.
Companies competing with Cosine for the same Google search keywords, organic and paid, via search-intersection analysis.
In the news
Cosine COO: AI belongs in the bunker, not the cloud – Resilience Mediaresiliencemedia.co · Jul 2026Frequently asked questions
- What does Cosine do?
- Cosine Red Team is an AI-powered security testing platform that identifies attack paths and vulnerabilities in critical systems through automated scanning and adversarial exploitation. The platform serves enterprise customers seeking to strengthen their security posture across APIs, code, authentication systems, data flows, and infrastructure.
- Who founded Cosine?
- Cosine was founded by Alistair Pullen, Yang Li, Sam Stenner in 2022.
- Who are Cosine's investors?
- Cosine's investors include Y Combinator, Lakestar.
- How much funding has Cosine raised?
- Cosine has disclosed $2.5M raised across 1 round.
- Where is Cosine headquartered?
- Cosine is headquartered in London, GB.