Senior Full Stack Engineer

Location: Remote (US) · Type: Full-time · Reports to: Head of Engineering · Comp: $150k-$170k

About Harness

Harness Giving (goharness.com) is a fundraising platform for nonprofits. Thousands of organizations have used us as a donor CRM and to take donations, sell event tickets, manage donors and run email and SMS campaigns. Hundreds of millions of dollars have flown through the Harness platform.

We're continuing to build out our CRM, but also building out Harness Intelligence. It's a set of AI agents and deterministic rules that analyze a nonprofit's fundraising data, identify opportunities to raise more money, recommend actions, and then execute those actions with the fundraising team's approval.

We're a small team building on a modern stack: TypeScript, NestJS and Next.js on AWS, gRPC between services, with PostgreSQL and Snowflake underneath.

The role

You'll own features end to end, from the React screen through the NestJS service to the database and back. You'll work across both the new AI platform and the existing CRM experience, including the services behind them.

What you'll do

• Build product in our Next.js / React / TypeScript Nx monorepo: the AI application experience, the donor CRM, segmentation, and email and SMS campaigns.
• Build and extend NestJS services, gRPC contracts and Postgres schemas behind those screens.
• Build the human-in-the-loop side of our agents: previewing what an agent drafted, approving or rejecting it, execution history and manual override.
• Build UI for AI output that people trust: streaming responses, structured answers with clear next actions, loading and error states that don't hide what happened.
• Ship behind feature flags, with logging, monitoring and a rollback plan.
• Write a short design doc before big builds. Review other people's.
• Get on calls with customers and customer success. Small team, so you'll hear the feedback directly.

What we're looking for

• You drive a collaborative culture. You pair with teammates, review generously, document what you build and share ownership instead of holding it close. You make the people around you better.
• 7+ years building production web applications, with 3+ years in TypeScript on both front end and back end.
• Deep React and Next.js: App Router, server components, state management, performance.
• Strong Node.js back end. NestJS preferred. You design APIs other people want to use. REST required; gRPC / Protocol Buffers a plus.
• PostgreSQL: schema design, migrations, query tuning.
• You've shipped on AWS (ECS, RDS, SQS/SNS) and are comfortable with Terraform or similar infrastructure as code.
• You've integrated payments and messaging: Stripe, Twilio, SendGrid or equivalents.
• You've built and shipped at least one user-facing AI feature to production.
• Product judgment. You make good calls without a PM writing every detail down.

How you'll use AI to build

We expect AI in your daily workflow. Not as a novelty. It's how the work gets done here.

• You use agentic coding tools daily (Claude Code, Cursor, Copilot or similar) and can show us your setup.
• You use AI to accelerate development, but you remain accountable for the architecture, implementation, quality and security of everything you ship.
• You use AI to generate tests, to scaffold services and screens, to draft design docs and to review pull requests.
• You own the output. You read every diff. You know where these tools go wrong: confident wrong code, invented APIs, stale library versions, quiet security holes. You have habits that catch it.
• You write the context that makes the tools useful for everyone: specs, repo instructions, prompts, reusable patterns.
• We already use AI agents internally, you make that tooling better.

In the interview we'll ask you to work a real task with your own tools while we watch. Bring your normal setup.

Nice to have

• Nonprofit, fundraising, CRM or fintech experience.
• Nx monorepos, Cloudflare Workers and Pages.
• LaunchDarkly and Datadog.
• Design systems (shadcn/ui) and accessibility.

What success looks like

• 30 days: Code in production by week two. You know how the CRM service, the communications service, the agent gateway and the front-end monorepo fit together.
• 60 days: You own a feature area end to end.
• 90 days: You've shipped a meaningful piece of the Advisor or CRM that customers use every week. The rest of the team uses something you built to make our AI tooling work better, like repo context files or test patterns.