Senior Software Engineer

Infinityy; New York (NY, MA); Hybrid; USD 140,000 - 210,000; Full time

Job summary

Infinityy is seeking a seasoned Software Engineer to own the user journey from signup to paid accounts. You will implement end-to-end flows across a React/TypeScript frontend and a C#/.NET backend, while integrating Stripe billing and instrumenting key activation and upgrade metrics.

You will collaborate with product design and a Program Manager, ship features end-to-end, and write tests to keep critical flows covered in CI. Real-world customer-facing auth/onboarding experience is required.

Qualifications

• 5+ years of professional software engineering experience across front end and backend.
• Experience with React and TypeScript in production.
• Shipped authentication, onboarding or account flows used by real customers.
• Hands-on Stripe or similar billing integration including subscriptions and webhooks.
• Experience with SQL Server, PostgreSQL or MongoDB and with Azure or AWS.

Responsibilities

• Own signup, login and SSO, including returning users to what they were doing after they create an account.
• Build buyer onboarding and the agent upgrade path, from freemium limits to paid plans.
• Build and run billing and subscriptions on Stripe, including plan changes, refunds and PCI-safe handling.
• Ship agent Workspace features end to end, across the React and TypeScript front end and C#/.NET APIs.
• Instrument activation, conversion and upgrade events so product can measure what's working.
• Work from specs with the product designer and Program Manager; push back when a flow isn't fully specified.
• Write tests alongside the QA engineer and keep critical account and payment flows covered in CI.
• Use AI coding tools (Claude Code, Cursor, Copilot) daily to move faster without lowering quality.

Skills

React

TypeScript

C# / .NET

Authentication flows

Billing integration

SQL databases

Azure / AWS

Product mindset

AI coding tools

Frontend & Backend

Tools

Stripe

SQL Server

PostgreSQL

MongoDB

Azure

AWS

Job description

You'll own the flows that turn visitors into users and users into paying customers: signup and login, buyer onboarding, the agent upgrade path and billing. You'll also build agent Workspace features end to end, from the React front end to our C#/.NET backend. Our other engineers own the viewer, integrations and AI; you own the path from first visit to paid account.

What you'll do

• Own signup, login and SSO, including returning users to what they were doing after they create an account
• Build buyer onboarding and the agent upgrade path, from freemium limits to paid plans
• Build and run billing and subscriptions on Stripe, including plan changes, refunds and PCI-safe handling
• Ship agent Workspace features end to end, across the React and TypeScript front end and C#/.NET APIs
• Instrument activation, conversion and upgrade events so product can measure what's working
• Work from specs with the product designer and Program Manager; push back when a flow isn't fully specified
• Write tests alongside the QA engineer and keep critical account and payment flows covered in CI
• Use AI coding tools (Claude Code, Cursor, Copilot) daily to move faster without lowering quality

What you'll bring

• 5+ years of professional software engineering, working across front end and backend
• Production experience with React and TypeScript, plus C#/.NET or a similar typed backend
• Shipped authentication, onboarding or account flows used by real customers
• Hands‑on Stripe or similar billing integration, including subscriptions and webhooks
• Experience with SQL Server, PostgreSQL or MongoDB, and with Azure or AWS
• A product mindset: you care whether a flow converts, not just whether it works
• Real-world use of AI coding tools as part of your daily workflow

Nice to have

• Growth engineering or experimentation (A/B tests, feature flags)
• SSO and identity providers (Auth0, Azure AD B2C, Clerk or similar)
• Product analytics tooling (Amplitude, Mixpanel, PostHog or similar)
• Proptech, marketplace or freemium SaaS experience

First 90 days

• 30: own the signup and login code; return-to-action after signup working
• 60: agent upgrade path and Stripe billing live; conversion events instrumented
• 90: buyer onboarding improvements shipped; activation and upgrade rates reported each release

About Infinityy

Infinityy is the decision-making layer for places and spaces, helping people move from initial interest to a confident decision with the information, context and human connection they need, when they need it. Its AI-powered platform brings collaborative property experiences, real-time answers, neighborhood intelligence and direct access to real estate professionals into one connected experience. The platform translates into 12 languages, while its AI assistant answers questions in more than 70.

An early-stage startup, Infinityy is backed by Second Century Ventures, the strategic investment arm of the National Association of REALTORS®, and was selected for its 2024 REACH Commercial and 2025 REACH Residential programs.

Equal Opportunity Employer

Infinityy is an equal opportunity employer. We welcome applicants of all backgrounds and do not discriminate on the basis of race, color, religion, sex, sexual orientation, gender identity or expression, national origin, age, disability, genetic information, veteran status, or any other characteristic protected by law.

Infinityy offers a variety of benefits to its employees, with details shared during the interview process.