Plainsea
Sofia, Bulgaria
About
Founded in 2022, Plainsea is a cybersecurity company based in Sofia, Bulgaria working in penetration testing, offensive security, application security.
Plainsea is a cybersecurity company that provides an offensive security platform for penetration testing. The platform supports human-led, AI-assisted and fully autonomous testing under a shared governance model, with scope and authorization controls, evidence capture, reporting and remediation tracking. Its agentic AI capability runs continuous web application testing to confirm which vulnerabilities are actually exploitable, with human-in-the-loop controls at critical decision points. The platform is aimed at security teams and pentesting providers, including MSSPs and MSPs. Plainsea was co-founded in 2022 and is headquartered in Sofia, Bulgaria, with a US presence in Massachusetts. In 2025 it achieved ISO/IEC 27001:2022 and ISO 9001:2015 certifications.
Location
Founded
Focus areas
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Services & products
Security domains
How they deliver
Products
Plainsea Platform
Penetration testing platform
Offensive security platform for managing penetration tests, scope and authorization, evidence, reporting and remediation tracking, with human-led, AI-assisted or autonomous delivery modes.
Plainsea Agentic AI Penetration Testing
Autonomous penetration testing
Multi-agent AI system that maps web applications, executes attack paths within defined rules of engagement, and validates which findings are exploitable, with human-in-the-loop controls.
Guardian Agent
AI agent safety layer
Monitors autonomous agent actions in real time, enforces the defined scope perimeter, and neutralises prompt injection attempts during testing.
Customers
Compliance & partners
Compliance frameworks
Technology partners
Credentials & affiliations
Certifications
ISO/IEC 27001:2022
ISO 9001:2015
Awards
1 Employer in Bulgaria
People
Management & team (4)
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