Freelance Integration Software Engineer Jobs in Romeoville, IL

Mashgin powers the world's best checkout experience for over 40 million users. Customers just place their items on our kiosks and our AI rings up their entire order in less than a second. With Mashgin, lines are now optional.

Mashgin's technology powers over 1 billion transactions at your favorite locations, including over half of all US professional sports teams, 4,000 convenience stores, major airports, universities, and more.

We’re not just building cutting‑edge AI—we’re creating real‑world impact and unforgettable experiences. Backed by a well‑funded Series B, we’re also one of the rare AI startups that’s already profitable.

Our secret? A culture of extreme ownership, autonomy, and customer obsession. At Mashgin, we are building something extraordinary by challenging conventional wisdom. We’ve thrown out the old rules to focus on what truly matters: creating a kickass product that makes people say, ‘Wow’. We don’t care about short‑term wins; we build systems that stand the test of time. If you thrive in a culture of excellence without compromise and want to see your work have an immediate, remarkable impact, you’re in the right place.

We are looking for a highly technical Senior Software Engineer, Integrations to join us in building high and low level software to connect Mashgin's autonomous checkout kiosks to various convenience store backends. You will be responsible for integrating our hardware and software with customer environments, payment systems, point-of-sale solutions, and enterprise apps so our checkout feels seamless.

This is a multi-layered software engineering role. You will be responsible for engineering APIs, app services, embedded systems, and networks to solve integration gaps. From building critical software so kiosks and customer systems communicate correctly to incorporating new payment terminals and peripherals, you’ll own critical pieces of tech that power retail transactions.

We maintain a flat, high-impact engineering culture where every engineer who joins our team carries the title of Member of Technical Staff. We expect this hire to commute 2 times a week to Woodridge, IL and to occasionally meet customers in‑person.

• Impact: You will own significant responsibility and have total ownership over your work. We stay lean and efficient, so your work directly impacts the product we ship every day.
• Simplicity: Complexity is a waste of time here—we take pride in building things that just work.
• Hard Work: Forget the glamorous research papers. We prioritize the hard work it takes to achieve real-world clarity and accuracy. You will innovate relentlessly to push the boundaries of what’s possible in visual automation.
• Humility: No task is beneath you. Whether it's high-level architecture or grunt work to fix a bug, we check our egos at the door and get real work done.
• Ruthless Prioritization: If everything is on fire, nothing is. You will be expected to prioritize ruthlessly, cutting through distractions to focus on the most impactful product improvements.
• Customer Innovation: We are customer-centric, not customer-pleasing. You won’t bend to every client demand; you will let innovation drive the product forward to solve the real problems our users face.
• Efficiency: Meetings suck. We keep them short and only use them for alignment, giving you your time back to focus on real work.

• Engineering Robust Integrations: Building and maintaining integrations between Mashgin's checkout kiosks and customer payment, point-of-sale, and enterprise systems to enable reliable, scalable deployments.
• Connecting Hardware & Software: Developing software that bridges embedded devices, payment terminals, peripherals, backend services, and customer APIs into a seamless end-to-end experience.
• Solving Complex Customer Challenges: Working directly with internal teams and enterprise customers to understand integration requirements, troubleshoot production issues, and deliver elegant technical solutions.
• Building Integration Infrastructure: Designing and implementing reusable libraries, tooling, and services that accelerate future customer integrations while improving reliability and observability.
• Debugging Across the Stack: Diagnosing and resolving issues spanning firmware, networking, operating systems, payment devices, cloud services, and distributed applications.
• Prototyping & Shipping: Rapidly building, testing, and deploying integration solutions, bringing new payment devices, peripherals, and customer systems into production with speed and confidence.

• 5+ years relevant coding experience
• B.S. or higher in Computer Science (or equivalent work experience)
• Excellent knowledge of one or more of these languages: Python, C++, TypeScript
• Comfortable learning new languages, libraries, and frameworks when the solution calls for it.
• Experience building production-ready code that’s used regularly by lots of people.

• Experience building software from firmware up to the application layer, especially for a public facing device
• Solid, working experience building software that closely interacts with hardware (payment systems, point of sales, fuel controllers are a plus)
• Strong proficiency with Python, C, and C++
• Experience meeting with and demoing new features for customers.

• An opportunity to work on a small, multidisciplinary team with the potential to break new ground in many different industries
• Excellent health, dental and vision insurance for you and your dependents
• 401k plan
• Flexible PTO policy
• Catered lunch in office with fully stocked snacks and beverages
• Pet insurance for your fur babies
• Voluntary life insurance plan
• Competitive salary and options in a small, rapidly scaling company

$115,000 - $210,000 a year
For roles based in Palo Alto, CA, the overall market range for Mashgin is typically $115,000 - $210,000 USD annually. Note that total compensation for this position will be determined by candidate’s relevant qualifications, work experience, skills, and other relevant factors. This estimate excludes the value of any benefits offered by Mashgin, and the potential future value of any other long-term incentives.

Mashgin is proud to be an equal opportunity employer. Individuals seeking employment at Mashgin are considered without regards to race, color, religion, national origin, age, sex, marital status, ancestry, physical or mental disability, veteran status, gender identity, or sexual orientation.