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Replit

Builds an AI agent that creates and hosts apps

AI Agent Security Architect

Full-Time
$230 - $350/yr+ Equity + 4% 401(k) match
Senior
Foster City, CA, USA
Hybrid
CybersecuritySecurity Engineering & Architecture

About the job

Requirements
  • At least 6 years of experience in security engineering or security architecture, including at least 2 years dedicated to AI/ML security, LLM application security, or securing agentic frameworks.
  • Deep understanding of agentic architectures and protocols, including Model Context Protocol, LangChain, AutoGen, CrewAI, ReAct frameworks, and vector database technologies.
  • Hands-on expertise with agentic AI threat vectors, including indirect prompt injection, goal hijacking, tool parameter tampering, data poisoning, and context contamination.
  • Strong background applying safety standards and risk frameworks such as OWASP Top 10 for LLMs and AI Agents, NIST AI RMF, and MITRE ATLAS.
  • Proficiency in Python, Go, or TypeScript/JavaScript, with experience reviewing code and building functional security tooling or guardrails.
  • Experience authoring, maintaining, and evangelizing technical security architecture documentation.
  • Ability to communicate complex non-deterministic AI risks to technical engineers and executive stakeholders.
  • A proven track record of contributing to an enterprise Cybersecurity Risk Register.
Responsibilities
  • Define the long-term vision and architectural patterns for securing autonomous agent workflows, Model Context Protocol integrations, multi-turn reasoning loops, and multi-agent coordination.
  • Architect and deploy dynamic input/output guardrail systems, semantic firewalls, and real-time intent verification filters to prevent goal hijacking, system prompt leaks, and indirect prompt injections.
  • Partner with Infrastructure and AppSec teams to design secure, short-lived, micro-isolated environments, such as microVMs, WebAssembly, and container sandboxes, for agents executing code, running shell commands, and interacting with host operating systems.
  • Conduct threat modeling against non-deterministic systems and lead automated and manual AI red-teaming initiatives to identify vulnerabilities in RAG context pipelines, vector stores, and tool-calling interfaces.
  • Architect fine-grained permission models and step-up Human-in-the-Loop authorization patterns for agents acting on behalf of users, ensuring agents do not exceed delegated privileges or misuse API keys.
  • Design data isolation and poisoning-prevention controls for vector databases, retrieval-augmented generation pipelines, and long-term conversation memories across multi-tenant workloads.
  • Define, document, and maintain authoritative secure design patterns and SDKs for teams building internal or customer-facing AI agent capabilities.
  • Identify, quantify, and document non-deterministic and agentic security risks, ensuring they are represented accurately in the Cybersecurity Risk Register.
  • Design tamper-evident logging and telemetry standards for agent reasoning chains, tool execution history, and context assembly to support incident response, forensics, and GRC requirements.
  • Partner with GRC to translate AI security controls into enterprise audit documentation and support Sales with enterprise security inquiries regarding AI safety.
Desired Qualifications
  • Experience designing runtime sandboxing and isolation technologies, such as Firecracker, gVisor, Docker, and WebAssembly, for dynamic code execution environments.

About the company

Replit runs a browser-based platform where people build software by describing it in plain English, and its AI agent handles every step from writing the code to putting the finished app online. After launching Replit Agent in 2024, it became one of the best-known names in vibe coding, the practice of building software from plain-language prompts. Users chat with the agent from a browser or phone as it plans, writes, and tests each change, then publish websites and mobile apps with built-in databases on Replit's own hosting. Individuals pay monthly subscriptions that include AI usage credits, and companies buy enterprise plans with added security controls. Replit was founded in 2016 and is based in Foster City, California.

Company Size

501-1,000

Company Stage

Series D

Total Funding

$872.2M

Headquarters

Foster City, California

Founded

2016

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Simplify's Take

What believers are saying

  • Equity has tripled in value: Replit's valuation jumped from $3 billion in September 2025 to $9 billion in March 2026.
  • Hiring is accelerating: opening London in September 2026, Replit said it expects to double headcount within a year.
  • Sales cover AI costs: Replit's revenue had exceeded direct costs, including AI models, for over a year by May 2026.

What critics are saying

  • Its closest rival is worth more: Swedish startup Lovable hit $13.3 billion in August 2026, versus Replit's $9 billion.
  • Expect crunch weeks: Replit says engineers often work up to 16 hours a day in sprints before big launches.
  • A key supplier competes: Claude maker Anthropic's own coding agent reached an estimated $2.5 billion yearly revenue by early 2026.

What makes Replit unique

  • Security is its enterprise edge: each deployed app runs in its own isolated Google Cloud project with a private database.
  • Engineers manage AI agents: per-person code output nearly tripled from January to June 2026 as Replit doubled its engineering team.
  • Its corporate reach tops rival Lovable's: Replit had users at 85% of the Fortune 500 in September 2026, versus two-thirds.

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Benefits

Competitive salary & equity

Your choice of new equipment & software

Health, dental, & vision insurance

Autonomy at work

Flexible work hours

Learning & development stipend

Monthly health & wellness stipend

Generous parental leave

Unlimited PTO (2 weeks minimum required)

401k matching

Commuter benefits

Expensed lunch

Yearly off-sites

Growth & Insights and Company News

Headcount

6 month growth

2%

1 year growth

5%

2 year growth

-8%
Tribe Techie
Sep 28th, 2026
Replit acquires Atta to bring AI business analysis in-app

Replit has acquired AI analytics startup Atta to enable users to perform business analysis and charting directly within its chat interface without writing SQL. The deal, announced on 25 September, brings Atta's data visualisation technology into Replit's platform. Co-founders Omar Shaik and Amine Ben Khalifa have joined the company. Financial terms were not disclosed. The integration is live through Replit Agent, allowing users to upload datasets, ask questions in plain language, and receive interactive charts. The system automatically handles analysis and selects appropriate visualisations based on queries. This expands Replit's capabilities beyond software development into business data analysis, aiming to reduce reliance on specialist analytics workflows and streamline decision-making for lean teams.

Tech.eu
Sep 8th, 2026
US AI coding startup Replit to hire 100 staff in London, mocks Silicon Valley 'monoculture

US AI coding startup Replit has opened its first overseas office in London, with plans to grow its team from 20 to around 100 staff by early next year. The San Francisco-based company joins other US tech firms expanding in London's King's Cross, including OpenAI and Anthropic. CEO Amjad Masad praised London's diversity compared to Silicon Valley's "monoculture", noting the capital offers exposure to artists, finance professionals and filmmakers alongside tech workers. London mayor Sadiq Khan attended the launch event. Replit specialises in AI-assisted coding tools and claims over 60 million users globally, including clients at 85 per cent of Fortune 500 companies. The firm raised $400 million in March at a $9 billion valuation, with backers including Databricks Ventures and Y Combinator.

PR Newswire
Sep 8th, 2026
Replit opens London office to double headcount and upskill 100 disadvantaged young people

Replit, the agentic creation platform with over 60 million users worldwide, has opened its first international office in London. The company, founded in 2016, celebrated the opening with London Mayor Sadiq Khan at a ribbon-cutting ceremony. The San Francisco-based firm will use London as its European operations hub. Replit plans to double its headcount and investment in the coming year. European enterprise customers already using the platform include PwC, Ernst & Young, Mercedes-Benz Group, TrustPilot and Hg. Replit announced a partnership with The Lord Mayor's Appeal charity to pilot a four-week coding course for 100 young Londoners not in education, employment or training. The programme aims to provide vital coding skills for employment opportunities.

TechBuzz AI
Sep 4th, 2026
Replit soars to $3B valuation on 53x revenue explosion to $150M

Replit has raised $250 million at a $3 billion valuation, driven by explosive revenue growth from $2.8 million to $150 million annualised in under 12 months — a 53-times increase. The AI-powered coding platform allows developers to build and deploy AI applications without infrastructure complexity. Prysm Capital led the round, with participation from Amex Ventures, Google's AI Futures Fund, Y Combinator, Craft Ventures, Andreessen Horowitz, and Coatue. Total funding now stands at around $478 million. Founded in 2016 by Amjad Masad, his brother Faris, and Haya Odeh, Replit has integrated deeply with Google Cloud whilst recently expanding to Microsoft Azure. The company's end-to-end platform approach has resonated with developers and enterprises seeking rapid AI development capabilities.

TechCrunch
Aug 24th, 2026
Replit CEO to discuss coding's AI revolution at TechCrunch Disrupt 2026

Amjad Masad, CEO and co-founder of Replit, will speak at TechCrunch Disrupt 2026 in San Francisco from 13–15 October. He will discuss the future of programming and the implications of AI-enabled development for both novice and professional coders. Replit has experienced explosive growth, with its current run-rate tracking toward significant expansion compared with just $2.8 million in reported revenue in 2024. Investors assigned the company a higher valuation earlier this year, six months after it received a $3 billion valuation. The session will explore how Replit helps users move beyond prototyping to fully developing their ideas. Masad's talk will address entrepreneurship and programming in the AI era.