96 YC Security Startups

96 Y Combinator companies carry the Security tag in YC's own directory, across every batch since 2005. Each row shows what the company does, its batch, HQ and status, and links to its YC application reconstructed in the real form, so a founder building a Security startup can read how accepted companies answered the same questions.

Companies
96
Top industries
B2B, Consumer and Fintech
Top locations
San Francisco, New York and Palo Alto
YC top companies
1
96 reconstructed applications

Read the YC application of all 96 companies

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The first 96 companies, top companies first

2
AccessOwl
AccessOwlManaging your Employees' Access to SaaS
Summer 2022Berlin, Berlin, GermanyActive
3
AeroFS
AeroFSSecure Enterprise Collaboration.
Summer 2010Palo Alto, CAAcquired
8
Anjuna
AnjunaAnjuna enabled organizations to trust any infrastructure
Winter 2018Palo Alto, CAActive
9
Apozy
ApozyApozy makes every website safe to browse
Winter 2017San Francisco, CAActive

That is 10 of 96.

Every company below has its YC application reconstructed in YC Insights. Create a free account to read them all.

Read all 96 applications
11
Argument Computer Corporation
Argument Computer CorporationAccelerate verifiable computing
Winter 2022Boston, MAActive
13
Authy
AuthyAuthy is a Two-Factor Authentication platform for developers
Winter 2012San Francisco, CAAcquired
14
authzed
authzedCloud Infrastructure for Authorization
Winter 2021New York, NYActive
15
Bannerman
BannermanSecurity Guard Company Marketplace
Summer 2014San Francisco, CAInactive
16
Better Auth
Better AuthThe authentication framework for TypeScript
Spring 2025San Francisco, CAActive
17
Blyss
BlyssEnd-to-end encrypted AI.
Winter 2023San Francisco, CAInactive
19
Castle
CastleBlock bots & bad behavior
Winter 2016San Francisco, CAActive
20
Clawvisor
ClawvisorThe Authorization Layer for AI Agents
Spring 2026San Francisco, CAActive
21
Clearly AI
Clearly AIAutomate security and privacy reviews
Summer 2024Seattle, WAActive
22
Cloudanix
CloudanixCloud and Container Security Platform
Summer 2021Sunnyvale, CAActive
23
Conifer
ConiferLeast cost routing system to reduce 70%+ token spend
Summer 2026San Francisco, CAActive
25
Corgea
CorgeaCorgea finds, and fixes insecure code and packages autonomously.
Summer 2023San Francisco, CAActive
26
Cotool
CotoolAI Agents for Security Operations Teams
Spring 2025San Francisco, CAActive
28
Decawork
DecaworkTraining company-specific models that approve AI actions.
Summer 2026San Francisco, CAActive
29
Documents.Me
Documents.MeClient-side encryption for your devices and the cloud.
Winter 2012Santa Clara, CAInactive
31
Dyneti Technologies
Dyneti TechnologiesReduce payment fraud
Winter 2019San Francisco, CAActive
32
EdgeBit
EdgeBitAutofix your software dependencies
Winter 2023San Francisco, CAAcquired
33
EnvKey
EnvKeyEnd-to-end encrypted configuration and secrets management
Winter 2018San Francisco, CAInactive
35
Federacy
FederacyPenetration testing and bug bounty platform.
Summer 2018San Francisco, CAActive
38
Firezone
FirezoneEasiest way to set up Zero Trust Access for your team
Winter 2022San Francisco, CAActive
39
Fuzzbuzz
FuzzbuzzFuzzing as a Service
Winter 2019San Francisco, CAAcquired
41
Golf
GolfAgentic AI Security and Governance
Spring 2025San Francisco, CAActive
42
idemeum
idemeumAI-powered Application Control
Summer 2021Palo Alto, CAActive
43
Incandor
IncandorBehavioral intelligence infrastructure for anti-fraud
Spring 2026San Francisco, CAActive
45
JumpWire
JumpWireDynamic access controls for all data and databases
Winter 2022New York, NYAcquired
46
Keyri
KeyriSecure fraud prevention and authentication platform for developers
Summer 2021San Francisco, CAAcquired
48
LogosGuard
LogosGuardThe risk management software for enterprises adopting AI
Fall 2025San Francisco, CAActive
50
Mattermost
MattermostSecure Collaboration for Technical Teams
Summer 2012Palo Alto, CAActive
52
Nebula Security
Nebula SecurityAutonomous AI defense system for cyber attack
Summer 2026San Francisco, CAActive
54
OneCLI
OneCLIThe open source AI teammates for your company.
Summer 2026San Francisco, CAActive
57
Palitronica Inc
Palitronica IncDetect cyber attacks on critical physical infrastructure
Winter 2022Kitchener, ON, CanadaActive
61
PromptArmor
PromptArmorLLM Security and Compliance
Winter 2024San Francisco, CAActive
62
Quantstamp
QuantstampSecurity auditing for Web3
Winter 2018San Francisco, CAActive
63
Reality Defender
Reality DefenderEnterprise Deepfake Detection
Winter 2022New York, NYActive
64
Rescue Forensics
Rescue ForensicsActionable human trafficking intelligence
Winter 2015Nashville, TNInactive
65
Rimward
RimwardLow-false-positive intrusion detection for remote outdoor sites
Summer 2023Paris, ĂŽle-de-France, FranceActive
66
Riot
RiotCybersecurity awareness for fast growing companies
Winter 2020Paris, ĂŽle-de-France, FranceActive
67
Risotto
RisottoRisotto auto-solves IT support requests using AI
Winter 2024San Francisco, CAActive
69
Silmaril
SilmarilPrompt injection defense that is self-healing
Spring 2026San Francisco, CAActive
70
SlashAuth
SlashAuthThe solution for fine-grained access control in web3
Winter 2021San Francisco, CAInactive
71
Slauth.io
Slauth.ioThe IAM Policy Copilot
Summer 2022Tel Aviv-Yafo, Tel Aviv District, IsraelInactive
72
Smyte
SmyteSmyte stops bad actors on social networks and marketplaces.
Winter 2015San Francisco, CAAcquired
73
Squire.ai
Squire.aiNever code alone.
Summer 2021San Francisco, CAInactive
75
Superagent
SuperagentRed teaming for AI agents
Winter 2024San Francisco, CAActive
76
Swif.ai
Swif.aiThe guardrail for AI on every device
Summer 2020Sunnyvale, CAActive
77
Tall Poppy
Tall PoppyProtecting your employees against online harassment
Summer 2018San Francisco, CAActive
78
Telivy
TelivyAutomate your cyber security risk assessments
Summer 2021San Francisco, CAAcquired
79
Templarbit
TemplarbitProtecting applications from malicious activity
Summer 2017San Francisco, CAAcquired
81
Tinfoil
TinfoilEncrypted AI with verifiable privacy
Spring 2025San Francisco, CAActive
82
Tracecat
TracecatThe open source AI-native security automation platform
Winter 2024New York City, NYActive
83
Traceforce
TraceforceCrowdStrike for AI Agents
Summer 2026San Francisco, CAActive
87
Vectrix
VectrixScan your SaaS apps and instantly identify security issues
Summer 2020San Francisco, CAAcquired
88
Verdict Machine
Verdict MachineAI cybersecurity for financial institutions' digital assets
Summer 2026Tel Aviv-Yafo, Tel Aviv District, IsraelActive
90
Visual One
Visual OneAI for security cameras
Winter 2020San Francisco, CAInactive
91
winfunc
winfuncai-native security engineering for mission critical codebases
Summer 2024San Francisco, CAActive
92
WireOver
WireOverReally secure file sending for big files.
Winter 2012Cambridge, MAInactive
94
WorldQL
WorldQLCustom AI harnesses for enterprises
Winter 2022San Francisco, CAActive
95
Xeol
XeolClose your outdated dependency attack vector
Summer 2023New York, NYAcquired
96
ZeroPath
ZeroPathAutomatically find and fix your software vulnerabilities
Summer 2024San Francisco, CAActive

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About this list

This list is part of Round Funded, an investor database and outreach platform for founders. It covers 60,000+ active VCs, angels, family offices and accelerators with verified contacts, lets you send pitches from your own Gmail, and includes a free Data Room for your raise. How this data is built.

Frequently Asked Questions

How many Y Combinator companies are in tagged Security?

This directory lists 96 YC companies in tagged Security, out of 6,207 across every batch since 2005. The count updates when the directory is refreshed, and every one of them is on this page with a link to its public profile.

Are the YC applications on these pages real?

No. YC keeps submitted applications private. Every application linked from this list is a reconstruction: the real YC form questions, answered from the company's public data. The Company section is free on each page; the rest opens in YC Insights.

Which companies on this page are best known?

Sqreen lead the table above. YC marks 1 of the 96 companies here as top companies, its own list of the highest-valued and highest-revenue alumni.

How do I use this list when applying to YC?

Pick five companies on this page whose product is closest to yours, read their reconstructed applications side by side in YC Insights, and note how each answers the same question. Then write your own answers to that standard.

Where does this data come from?

From YC's public company directory, refreshed by batch, with each company's status, industry and location as YC reports them. Round Funded adds the reconstructed application and the founder profiles; nothing private is published.

What is Round Funded?

Round Funded is an investor database and outreach platform for startup founders. It lists 60,000+ active investors with verified contacts, filtered to recent investment activity, and lets founders send personalized pitches from their own Gmail, track replies, and share a free Data Room. Round+ starts at $99 per month with a 3-day trial.