Senior Software Engineer, AI-Driven Systems

In 2023, Thimble was acquired by Arch Insurance, part of Arch Capital Group Ltd. (Nasdaq: ACGL), an S&P 500 company providing insurance, reinsurance and mortgage insurance worldwide. That gives us something rare: the speed, ownership and culture of a startup, with the balance sheet, stability and long-term commitment of one of the industry’s strongest insurers.

For more information, visit thimble.com.

Our Values
Our unique culture is built around our six core values:

Think Wild, Act Tame
Be relentlessly creative. Question everything. Get to know the rules so well, you can use them in new ways. Be the industry’s compliant radicals.

Green Means GO
Act. Move forward. Learn. You can only make a decision based on the best information you have – so make it.

Own Every Detail
Be ruthlessly precise. Disciplined. Sweat the small stuff.

Simplify, Simplify, Simplify
Get to the point. Make it crystal clear. Cut everything else. It’s our job to make insurance easy – however hard that is for us.

Every Moment Counts
Show up early and ready. Deliver on time or before. Make the most of your time, so others can make the most of theirs.

Stay Human
Treat every person, and their ideas, with respect. Cherish diversity.

About the Role
Thimble is investing in the next generation of its platform, and this engineer helps lead that work. Our backend is built on Node.js microservices and event-driven architecture on AWS, and we are evolving it toward durable, explicitly orchestrated workflows, with AI-native tooling at the center of how we build.
This is a hands-on role: you’ll write, review, and ship production code every day, with AI agents as your primary build partner. You’ll also shape technical strategy and set the patterns the rest of the team builds on.
You’ll work in Node.js and TypeScript every day, so you need to be productive in them from the start.

What You’ll Do
Design and build the durable workflows and services that will replace our current event-driven flows, defining service boundaries, state ownership, idempotency, and retry semantics Use of agentic coding tools on hard problems: setting up context, breaking down problems, and verifying output Write and ship production code in Node.js and TypeScript every day, using agentic coding tools (Claude Code and similar) as your primary way of working Define the reference patterns (service templates, shared libraries, code generators) that every rebuilt service follows Plan and execute the migration in increments that keep production running, with tested rollbacks Build and maintain the tooling around our AI workflow: MCP servers, evaluation scripts, and automated checks that hold AI-generated code to the same bar as hand-written code Instrument services with metrics, alerts, dashboards, and tracing, and own production incidents end to end Make targeted changes in our React and Angular applications when backend work requires them Partner with product, growth, and other engineers, and contribute to code reviews and architecture discussions

What We’re Looking For
Strong backend engineering with production experience in Node.js and TypeScript Hands-on experience building and operating distributed or event-driven systems, and a working understanding of how they fail Experience using AI tools to drive a large code migration at scale (framework upgrade, service rewrite, language port) Curiosity about agent harnesses, MCP, and A2A protocols; production deployment of agents is not required Experience contributing to a migration or re-platform on a live system Comfort reading unfamiliar code and data models and spotting problems in them Enough frontend literacy to trace a problem from the UI down to the service layer Clear written communication and comfort working in a remote, async-friendly environment

Bonus Points

Hands-on experience with a durable execution or workflow orchestration engine, in any language You’ve built or contributed to an MCP server, an agent harness, an evaluation suite, or a multi-agent system, whether as a side project, open source, or an internal tool Experience in InsurTech, FinTech, or another regulated industry in a similar environment to our tech stack

Thimbler Benefits & Perks!
-Fully remote company
-Thimble Fridays! (out of office at 12:00pm local time)
-Comprehensive health, vision, and dental coverage
-401(k) auto enrollment and matching (100% of the first 3% and 50% of the next 3%)
-PTO: 20 days vacation + 12 company-wide holidays + 8 floating days + 1 VTO (Volunteer Time Off) + unlimited sick time
-Parental Leave: 100% paid 12 weeks + 2 weeks gradual return
-Computer choice of Mac or PC
-Work from home setup reimbursement
-Monthly co-working space and/or child care reimbursement
-Monthly ClassPass credit
-Quarterly wellness reimbursement
-Other health & wellness perks including: One Medical, Teladoc, Talkspace, Kindbody, and Health Advocate
-Virtual events, happy hours, trivia, and fun!