---
title: 'River Markets - Founding Engineer - San Francisco, CA at Midwestern Interactive Growth Team'
canonical: 'https://feeny.ai/job/river-markets-founding-engineer-san-francisco-ca-midwestern-interactive-growth-4yy3gycqf9xw'
type: 'job'
last_seen: '2026-09-16'
---

# River Markets - Founding Engineer - San Francisco, CA at Midwestern Interactive Growth Team

- **Company:** Midwestern Interactive Growth Team
- **Location:** San Francisco, CA
- **Compensation:** $140k–$200k
- **Employment:** full-time
- **Work type:** onsite
- **Posted:** 2026-07-31
- **Last confirmed live:** 2026-09-16
- **Apply:** https://jobs.gem.com/midwestern-interactive/am9icG9zdDq1ICFejJukbR6z7TdzOQdG

## Job description

## About River Markets

I’m Antonin, co-founder and CTO of River Markets. Oscar (CEO) and I spent 3 years as quants in HFT shops and hedge funds. At nights and weekends we started trading predictions markets for fun and built a ton of trading infrastructure. We are now using this to build the prime brokerage and execution layer for prediction markets: the infrastructure professional and institutional traders need to access, trade, and manage risk across venues like Kalshi and Polymarket at scale.

We value ownership, speed, and a high technical bar. We expect to do more with fewer people than a team our size has any right to. We are currently fully connected to 3 exchanges, have 6 proprietary execution algorithms and already have paying users.

How we work: AI-native AI is the operating model. Every engineer treats AI as a core part of how they work: writing and reviewing code with AI tooling, automating their own workflows, and building internal systems that lean on LLMs where it makes sense. The bar isn't "can you use Claude": it's "what did you stop doing by hand this week?" We're looking for people who instinctively reach for automation, who multiply their output rather than just grinding harder, and who are excited that the leverage per engineer here is genuinely uncapped. We expect engineers to still understand every line they ship, AI-generated or not.

## What you'll do

As a founding engineer, you'll own core systems end to end, scoping features directly with the founders, designing the architecture, building backend and frontend, integrating with exchange APIs, and watching it run in production. Concretely, you'll:

- Build and maintain the systems behind our order book, execution stack, exchange connectivity and portfolio management.
- Integrate with external exchanges and APIs where reliability and latency matter
- Write high-quality, testable code and raise the bar on everyone else's through review
- Improve infrastructure, reliability, and observability so we can move fast without breaking our systems
- Help define our engineering culture, standards, and early hiring, you're setting the defaults the next ten engineers inherit

We expect the following:

- By week 1, you’ll have shipped in production a feature real traders use.
- By month 1, you’ll own a core system end to end, from architecture to monitoring.
- By month 3, you’ll have shared our engineering culture and be involved in our next hire

What we're looking for (we don’t expect you to check all the requirements!)

- Strong engineer (at least 2 YOE -full time- in SWE or similar role) who has designed, shipped, and operated production systems, not just written features, but kept them alive.
- Fluency in a modern language (Python, Go, Rust, or similar) and comfort across the stack: backend services, data pipelines, and user-facing components
- Solid grounding in system design, API design, and data modeling for low-latency, scalable applications
- AI-native by default, you already automate your own work and use AI tooling to ship more, faster
- Thrives in a small, high-ownership environment with minimal oversight
- Someone nice (we’ll spend a lot of time together) :) Bonus: experience in fintech, trading, or market infrastructure; a genuine interest in prediction markets

## Compensation, Benefits & Perks

- Base salary: $140,000–$200,000
- Equity: 0.5%–1.5%
- On-site in the San Francisco Bay Area
- Platinum health insurance plan, we cover 100% of the premium
- Unlimited PTO (minimum of 3 weeks, we don’t want a burned out team)
- Food provided in office
- Dog Friendly office
- Fresh fruits + snacks from farmer markets and local shops
- Monthly team building activity
- 401(k) match fully vested
- We sponsor visas.

## About Midwestern Interactive Growth Team

## Company Overview
- **One-liner**: Midwestern Interactive is a talent partner that provides embedded teams, scoped projects, and recruiting services for tech companies building in the AI era.
- **Entity Type**: Private (Bootstrapped/Corporate Round funding)
- **Headquarters**: Joplin, Missouri, United States
- **Founded**: 2012
- **Founders**: Matt Johnson (CEO/Owner)

## Core Business
- Primary industry/industries: Software Development, Talent & Staffing, Technology Consulting
- Target customers: Growing tech companies (from Fortune 500 to early-stage startups) that need to move fast without building everything in-house
- Mission or purpose statement: "We complete work with purpose and precision. We lead with humility, drive, and wisdom. We take care of what is entrusted to us, including time, budget, relationships, and trust."

## Products & Services
- **Embedded Teams**: Top-tier talent that integrates seamlessly with a client's team, providing specialized expertise that scales with the vision while maintaining flexibility as priorities shift.
- **Scoped Projects**: Time-defined project teams with clear objectives and predictable costs, covering Discovery, MVPs, technical validation, brand development, and more.
- **Recruiting Services**: Full-cycle talent acquisition for direct placement, contract-to-hire, or embedded recruiters, finding hidden talent aligned with technical needs and company culture.

## Market Standing
- **Valuation/Market Cap**: Not publicly available
- **Key Metric**: 80 employees (+11.0% YoY); 120+ clients served; 250K+ hours delivered annually; products have raised over $450M
- **Notable Investors/Partners**: Gloo (lead investor in 2025 Corporate Round)
- **Growth Signals**: 38.3% LinkedIn follower growth (yearly); expanding headcount with 12 new hires in the last year; multiple office locations across the US and Brazil

## Competitive Advantages
- **Three-in-one model**: Unlike traditional staffing agencies focused solely on headcount, Midwestern offers embedded teams, scoped projects, and recruiting under one US contract, providing flexibility that rigid staffing models cannot match.
- **US-led, global reach**: Globally sourced talent configured to a client's region, timezone, and budget, with all management under a single US contract.
- **13+ years of experience** with a track record of serving 120+ clients from Fortune 500 to early-stage startups.
- **Senior leadership depth**: CTO, VP of Scoped, Director of Engineering, Design Director, and other experienced leaders ensure high-quality delivery.

## Strategic Focus
- Current priorities include scaling the embedded teams model for AI-era work, expanding into new markets (notably Brazil), and deepening partnerships with growth-stage tech companies.
- Emphasis on "flexible talent, global reach" — enabling clients to scale up or down easily without overcommitting.

## Why Work Here
- **Culture**: Values-driven environment emphasizing clear communication, reliable follow-through, and commitment to quality. The team operates with humility, drive, and wisdom.
- **Work model**: Hybrid/remote-friendly with offices in Joplin (HQ), Springfield, and Dayton, plus a distributed workforce in Brazil.
- **Notable perks**: Opportunity to work on impactful products that have raised over $450M; exposure to a wide range of clients from startups to Fortune 500; clear career progression paths.
- **Engineering culture**: 39% of staff are in technical roles (47 people), with strong seniority distribution (26% specialist, 16% other management, 12% manager, 9% senior). Team members come from diverse backgrounds including DevMountain, Jack Henry, Leggett & Platt, and Gloo.
- **Growth opportunities**: 11% yearly headcount growth indicates a scaling organization with upward mobility for high performers.

## Sources
1. [Midwestern.com - Homepage](https://midwestern.com/)
2. [Midwestern.com - About Page](https://midwestern.com/about)
3. [Midwestern Interactive Career Page](https://careers.midwesterninteractive.com/apply)
4. [LinkedIn - Midwestern Interactive](https://linkedin.com/company/buildmidwestern)
5. [Built In - Midwestern Interactive Jobs](https://builtin.com/company/midwestern-interactive-llc/jobs)

## Other roles at Midwestern Interactive Growth Team

- [Director of Technical Delivery](https://feeny.ai/job/director-of-technical-delivery-midwestern-interactive-growth-team-united-states-pnf53g43zgbf) — United States
- [Masterworks - Finance & Billing Analyst - Hybrid](https://feeny.ai/job/masterworks-finance-billing-analyst-hybrid-midwestern-interactive-growth-team-7vccevfjj5b2) — Poulsbo, WA
- [Senior SRE - Remote, PST - Contract to Hire](https://feeny.ai/job/senior-sre-remote-pst-contract-to-hire-midwestern-interactive-growth-team-q1tycfm4r3ez) — United States
- [Technical Recruiters - 1099/Retained (Copy)](https://feeny.ai/job/technical-recruiters-1099-retained-copy-midwestern-interactive-growth-team-x5h6tqwdxp2z) — United States
- [Gloo - Staff Accountant](https://feeny.ai/job/gloo-staff-accountant-midwestern-interactive-growth-team-latin-america-vd6m61h3420s) — Latin America
- [River Markets - Financial Ops Lead - San Francisco, CA](https://feeny.ai/job/river-markets-financial-ops-lead-san-francisco-ca-midwestern-interactive-growth-y5a4qsfmsyd1) — San Francisco, CA