Founding Engineer

Caylex; San Francisco (CA); On-site; USD 120,000 - 160,000; Full time

Benefits offered by this job

Competitive salary

Equity options

Collaborative work environment

Job summary

A pioneering AI infrastructure company in San Francisco is seeking a Founding Engineer to shape its product and engineering culture. You will work on building scalable backend infrastructure, collaborating closely with the founding team to influence product development and company trajectory. The ideal candidate has over three years of experience in backend development, particularly with AI agents and distributed systems. This role offers the opportunity to join a small, driven team with a competitive salary and equity.

Qualifications

• 3+ years of experience in building large-scale backend infrastructure.
• Understanding of AI agents and scaling challenges.
• Experience building enterprise AI agents.

Responsibilities

• Work full-stack on infrastructure and user-facing features.
• Build high-performance infrastructure for external information access.
• Collaborate with founding team to influence product and company trajectory.

Skills

Large-scale backend infrastructure

Distributed systems

AI agents architecture

MCP systems

API development

Creative problem solving

Job description

Caylex is building the infrastructure layer that allows AI agents to interact with the external world. For agents to advance toward end-to-end workflows and operate with greater autonomy, they must be able to:

• Take actions across external platforms (applications, databases, APIs, the open web)
• Ingest and manage context from these sources at scale.

Today, agents struggle at every stage: connecting to external platforms, orchestrating tools as toolsets grow, and consuming external context that expands in scale and complexity.

Caylex solves these problems by providing the infrastructure to connect agents with external platforms of all kinds, orchestrate tools reliably, and manage context flows.

We believe agents will become the central actors orchestrating information across an ever-expanding network of external sources. This web of connections will form the foundation of the agentic internet – and Caylex will be the infrastructure powering it.

The Role

As a Founding Engineer, you’ll play a central role in shaping both our product and engineering culture. You will:

• Work full-stack across infrastructure, integrations, and user-facing product features.
• Build high-performance infrastructure that agents rely on to access external information.
• Push the boundaries of MCP-based systems, with opportunities to go deep on agent infrastructure.
• Take features from first-principles ideation to production-ready execution, balancing technical rigor with product velocity.
• Collaborate directly with the founding team, influencing not just the product but the company trajectory.

What We’re Looking For

You’ll thrive at Caylex if you:

• Have 3+ years of professional experience building large-scale backend infrastructure or distributed systems.
• Understand how AI agents are architected and the common challenges in scaling them.
• Enjoy owning large product features end-to-end and shipping high-quality code fast.
• Are comfortable making product and technical decisions from first principles in a space with little precedent.
• Are curious, creative, and thrive in a tight-knit, fast-paced environment.
• Are excited by the idea of building the foundation of the agentic internet.
• Have exposure to MCP, ideally through building servers and working with the MCP spec.
• Have experience building AI agents for enterprises.
• Have experience building developer platforms where APIs, tooling, and DX are the core product.

Why Join Us

• Shape the core architecture of a company at the frontier of AI infrastructure.
• Work side-by-side with the founder in a high-ownership, high-impact role.
• Join us in-person at our San Francisco office, collaborating closely with a small, driven team.
• Compensation: competitive salary + meaningful equity.

Seniority Level

Mid-Senior level

Employment Type

Full-time

Job Function

Engineering and Information Technology

Industries

Technology, Information and Internet

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