Cosine was founded by Alistair Pullen, Yang Li, Sam Stenner in 2022.

Who are Cosine's investors?

Cosine's investors include Eight Capital, Gaingels, Soma Capital, Y Combinator, Lakestar, Outward VC, UpHonest Capital.

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.

Cosine

YC W23

London, GB · Founded 2022 · 12 employees · Hiring · 7 known investors

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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 Inc. · Buildt, Inc. · Buildt

AI & Machine Learning Cybersecurity Developer Tools Enterprise Software Artificial Intelligence Generative AI Machine Learning NLPUnited KingdomEuropePartly Remote

Founders & leadership· Y Combinator alumni (W23)

Cosine was founded in 2022 by Alistair Pullen, Yang Li, and Sam Stenner.

Alistair Pullen CEO & 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.

Yang Li FounderYang 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.

Sam StennerCo-founder · Software Engineer

Investors · 7

Eight Capitallisted by Eight CapitalNorwalk

How we know: eightcapital.com · Not right? Tell us

Gaingelslisted by GaingelsNew York · $200K – $500K

How we know: gaingels.com · Not right? Tell us

Soma Capitallisted by Soma CapitalSacramento · $100K – $300K

How we know: somacap.com · open dataset · 5k.vc investor directory · Not right? Tell us

Y Combinatorlisted by Y CombinatorSan Francisco · $500K

How we know: the Y Combinator directory · open dataset · 5k.vc investor directory · Not right? Tell us

LakestarreportedZurich · $540K

How we know: funding news · Not right? Tell us

Outward VCreportedLondon · $1.3M – $6.3M

How we know: open dataset · 5k.vc investor directory · Not right? Tell us

UpHonest CapitalreportedSilicon Valley · $50K – $1M

How we know: a partner's Signal profile · Not right? Tell us

Funding

SEC filings, press & company announcements

$2.5M disclosed across 1 round · 2024

$2.5MraisedAug 2024 · 3 sources
Source ↗

Source: company announcements and press reports — follow each round's link for the claim.

The YC application· Winter 2023 batch

▶ Demo Day video — watch on YC ↗

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Companies working in the same space as Cosine.

Legal entities · 2

corporate structure

Buildt Inc.

Buildt, Inc.

In the news

Cosine 3.0 - one coding agent across every surface your team usesycombinator.com · Apr 2026

London-based Cosine raises €2.2 million to deliver autonomous AI software developers | EU-Startupseu-startups.com · Aug 2024

Cosine Raises $2.5M in Fundingfinsmes.com · Aug 2024

Frequently 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 Eight Capital, Gaingels, Soma Capital, Y Combinator, Lakestar, Outward VC, UpHonest Capital.
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.