Halcyon

Halcyon

Cybersecurity platform enabling automated decryption

Overview

Halcyon.ai provides an Anti-Ransomware and Cyber Resilience Platform on a subscription basis to safeguard businesses against ransomware. The platform works by automatically capturing encryption keys and enabling autonomous decryption to instantly recover infected devices, minimizing downtime. It also includes a resilience engine to accelerate system recovery and a Ransomware Readiness Report to help firms assess and improve their security posture. The solution is distinguished by its automatic decryption capability, key capture, and rapid recovery workflow, all embedded in a single platform. The goal is to prevent ransomware disruption, ensure business continuity, and reduce potential losses from cyber threats.

Significant Headcount Growth

About Halcyon

Simplify's Rating
Why Halcyon is rated
B
Rated B on Competitive Edge
Rated A on Growth Potential
Rated C on Differentiation

Industries

Data & Analytics

Enterprise Software

Cybersecurity

Company Size

201-500

Company Stage

Series C

Total Funding

$210M

Headquarters

San Diego, California

Founded

2021

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Simplify's Take

What believers are saying

  • September 10, 2026 Bain-backed $40M Series B funds GTM expansion and R&D.
  • April 16, 2026 Nielsen and Inglis add credibility with governments and regulated buyers.
  • RemoteFront listed 16 open roles on September 17, 2026, signaling hiring momentum.

What critics are saying

  • Windows kernel hooks create outage risk if File Resilience blocks legitimate processes.
  • Microsoft Defender and Sentinel dependence gives Microsoft leverage over Halcyon distribution.
  • Crowded ransomware market forces constant proof; a failed 2026 incident destroys trust quickly.

What makes Halcyon unique

  • July 28, 2026 File Resilience stops ransomware at Windows kernel level before encryption.
  • Halcyon pairs rollback key capture with 24/7 ROC eviction, not backup-dependent recovery.
  • March 31, 2026 HYCU partnership extends Halcyon into cloud and hybrid estates.

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Funding

Total Funding

$210M

Above

Industry Average

Funded Over

5 Rounds

Series C funding is usually for startups that are doing well and are looking for more money to fuel major growth, such as acquiring other companies, expanding into global markets, or launching new product lines. Investors typically include larger venture capital firms and private equity.
Series C Funding Comparison
Above Average

Industry standards

$50M
$50M
Medium
$62M
SeatGeek
$100M
Oura
$100M
Halcyon

Benefits

Health Insurance

Dental Insurance

Vision Insurance

401(k) Retirement Plan

401(k) Company Match

Unlimited Paid Time Off

Parental Leave

Company Equity

Growth & Insights and Company News

Headcount

6 month growth

↑ 8%

1 year growth

↑ 12%

2 year growth

↑ 14%
SYN Ventures
Sep 16th, 2026
Halcyon - SYN Ventures | Venture Capital for Cybersecurity Innovators

Halcyon is the first anti-ransomware platform built by offensive security experts to eliminate the business impact of ransomware.

Business Wire
Sep 12th, 2026
Halcyon Closes $40M Series B to Scale Mission of Defeating Ransomware

Halcyon, the leading platform designed from day one to defeat ransomware, today announced it has closed a $40M Series B funding round led by Bain Capital Ven...

MSSP Alert
Aug 4th, 2026
New file resilience tool stops ransomware before files are encrypted.

New file resilience tool stops ransomware before files are encrypted. August 4, 2026 Halcyon has launched File Resilience, a new capability that stops ransomware encryption before files are modified. Operating at the Windows kernel level, it monitors the sequence of actions ransomware must take to encrypt data and terminates the process as the attack begins. Halcyon said the approach is designed to work against known ransomware variants as well as previously unseen attacks that may not have an existing signature. Once an encryption attempt is blocked, the company's 24/7 Ransomware Operations Center investigates the incident, contains the threat, and works to remove the attacker from the environment. Moving ransomware defense ahead of recovery. File Resilience adds a preventive layer to Halcyon's existing ransomware recovery capabilities. The company's rollback technology captures encryption key material during an attack and uses it to decrypt affected files directly, rather than relying on backups or shadow copies that attackers may delete. Seth Geftic, Halcyon Head of Marketing at Halycon told MSSP Alert, "Halcyon's existing rollback doesn't use backups. It captures the ransomware's encryption key material during the attack and uses it to decrypt files directly. But it's still reactive. Recovery happens after encryption, and without eviction, the attackers are still on the network and can simply re-encrypt the device." File Resilience is designed to act earlier in the attack. According to Halcyon, it serves as the first layer in a three-part approach that stops encryption, limits the blast radius, and captures key material for recovery. "File Resilience sits earlier, with kernel-level, real-time detection that stops encryption as it happens," Geftic said. "Key capture and decryption remain the safety net behind it, with no backups required either way." The shift matters because encryption is often the point where a ransomware incident turns into a business disruption. Stopping that process can keep systems and files available while responders investigate how the attacker entered the environment and what access remains. Microsoft integrations bring response into existing workflows. Halcyon also announced native macOS support, scheduled for general availability in August, along with expanded integrations for Microsoft Defender and Microsoft Sentinel. The Microsoft integrations are available now and are designed to bring Halcyon alerts and response activity into security workflows that customers already use. For Microsoft Defender customers, Halcyon continuously monitors the health and integrity of the endpoint security platform, including attempts to disable or bypass it. Halcyon can also trigger Defender response actions, such as isolating a compromised host. "Halcyon backstops Defender itself," Geftic said. "If Defender is tampered with or disabled, Halcyon keeps detecting and blocking ransomware independently." The Defender integration also allows analysts in Halcyon's Ransomware Operations Center to isolate Defender-managed assets directly from the Halcyon console during an active incident. That can reduce the need to move between separate security tools while an attack is underway. The Sentinel integration sends Halcyon events and alerts into Microsoft Sentinel in near real time. The data is mapped to Microsoft's Advanced Security Information Model, allowing security teams to query it using Kusto Query Language and incorporate it into existing investigations, analytics and response workflows. The integrations allow customers to add Halcyon without replacing their Microsoft security tools. Halcyon can operate alongside Defender and Sentinel while adding controls focused specifically on ransomware encryption, recovery, and response. Blocking encryption does not end the attack. Preventing file encryption addresses one part of a ransomware incident. Attackers may still have stolen data, gained privileged access, or established persistence elsewhere in the network. Halcyon said its Data Exfiltration Protection capability operates continuously to detect and stop potential data theft, including activity identified through DNS and volumetric monitoring. "Once encryption is blocked, the attacker may still have stolen data or gained privileged access," Geftic said. "Our Data Exfiltration Protection runs 24/7 to identify and halt potential exfiltration, with an immediate investigation when suspicious activity is detected." Halcyon's eviction workflows run alongside forensic investigations and are designed specifically for ransomware incidents. The company said the workflows automate containment tasks, allowing responders to spend more time examining the cause of the breach, identifying affected systems and removing the attacker's access. "The Halcyon ROC investigates and disrupts the attack, leads recovery and works to fully evict the attacker," Geftic said. "That includes decrypting affected data using captured key material when files have already been encrypted." By pairing kernel-level blocking with Microsoft integrations, data exfiltration monitoring and human-led response, Halcyon is trying to reduce both the operational damage of ransomware and the time required to remove an attacker from the environment. However, the broader value of File Resilience will depend on whether it can stop encryption without disrupting legitimate activity and whether security teams can move quickly from prevention to full containment. An in-depth guide to ransomware. Get essential knowledge and practical strategies to protect your organization from ransomware attacks. Suparna is the Senior Managing Editor for CyberRisk Alliance's Channel Brands, including MSSP Alert and ChannelE2E. She manages content development, sharpens editorial workflows, and ensures storytelling is tightly aligned with audience needs. With a background in technology, media, and education, she combines strategic insight with creative execution.

PR Newswire
Jul 28th, 2026
Beazley Security and Halcyon launch cyber resilience retainer combining incident management and ransomware protection

Beazley Security and Halcyon have launched the Cyber Resilience Retainer, combining incident management, incident response, and ransomware resilience in a single offering. The retainer provides comprehensive support before, during, and after cyber incidents, moving beyond traditional incident response contracts that focus primarily on post-attack investigation. The service gives organisations access to cyber breach coaches, digital forensics experts, recovery specialists, and ransomware defence professionals through a single point of contact. Halcyon's contribution includes ransomware identification, containment, prevention of further encryption, and recovery support backed by its Ransomware Operations Centre. The retainer aims to eliminate procurement delays during crises by establishing relationships and response processes beforehand, enabling faster coordination and improved recovery outcomes.

PR Newswire
Jul 28th, 2026
Halcyon launches File Resilience to prevent ransomware encryption at Windows kernel level

Halcyon has launched File Resilience, a capability that prevents ransomware encryption by terminating attempts at the Windows kernel level before files are modified. The technology intercepts encryption attempts as they begin, removing attackers' primary leverage for extortion. The company is also introducing native macOS support, available in August, and deeper integrations with Microsoft Defender and Microsoft Sentinel. These additions extend ransomware protection across Windows, macOS, and Linux environments. When File Resilience blocks an encryption attempt, Halcyon's 24/7 Ransomware Operations Centre investigates and evicts the threat actor. Unlike traditional security tools that focus on detection or post-attack recovery, File Resilience is designed to stop encryption whilst it's happening. File Resilience is available immediately as part of Halcyon's ransomware resilience platform.

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