Senior Backend Engineer

Raintree Systems · Vilnius · €4,500–€8,000/month (stated in the posting)

Apply on the company website

About Raintree Systems​

Founded in 1983 and headquartered in Chandler, AZ, Raintree is a leading AI-powered EMR and practice management platform built specifically for physical, occupational, speech therapy, and ABA organizations. Powering millions of patient visits across thousands of locations, our award-winning, all-in-one software connects clinical, billing, and operational workflows—reducing administrative complexity and empowering therapy providers to scale with confidence and deliver superior patient care.

Spike Technologies Inc. is a VC-backed hyper growth B2B Agentic AI and health data startup founded in 2022, split between San Francisco, California, and Vilnius, Lithuania. Spike provides a multimodal Voice AI-powered platform designed to eliminate administrative burden in the healthcare industry. The company serves a diverse client base across healthcare, government, digital health and health insurance sector.

In July 2026 Spike Technologies was acquired by Raintree, leading EMR platform in US rehab industry!

As a Software Engineer in Spike AI Engineering team, you will build the systems at the forefront of GenAI and Voice recognition and synthesis for real-time agentic use-cases. You will be operational in optimizing the software for low latency while maintaining flexibility, accuracy, scalability and compliance in Health care workflows.

Core Responsibilities:

• Optimize the voice AI platform for lower latency and improved scalability using open-source technologies.

• Develop interfaces and parallel processing for connecting system components (STT, VAD, LLMs, TTS, external APIs).

• Implement data synchronization mechanisms for voice and text streams in parallel workflows.

• Create abstraction layers for scalable LLM usage, balancing cost, performance, and accuracy.

• Enhance internal tools for system observability, monitoring, and data inspection at scale.

• Build integrations to connect clinical workflows with our systems.

Qualifications

• At least 4 years in software engineering

• Strong analytical and quantitative problem-solving skills, with an aptitude for tackling complex technical challenges.

• Proven ability to quickly learn and adapt to new technologies and concepts.

• High degree of initiative and a strong sense of ownership over project outcomes.

Good to have (at least one)

• Experience with video or audio streaming, or low latency image processing software development

• Experience maintaining and scaling websockets

• Personal projects demonstrating your mathematical skills

• Contributions to open source software

What we offer:

• Competitive salary in the range of 4,500 to 8,000 eur gross (and more in exceptional cases) per month depending on your qualifications.

• Annual bonus.

• Hybrid working model (offices in Vilnius, Lithuania and Palo Alto, CA)

• Personal health fund, optical allowance, referral bonus, team events.

• Dynamic growth: dive into AI and Data tech, seizing high-growth opportunities with cutting-edge projects.

• Talented peers: collaborate with a smart, ambitious team comprising data scientists, PhDs, Cambridge alumni, and tech industry pros (formerly from Bloomberg, Amazon, and Google).

• Solid backing: enjoy stability and ample resources for success, supported by market leader Raintree.

At Spike Technologies, diversity is celebrated, and inclusion is our priority. We welcome applicants from all backgrounds to join our innovative team and contribute to our inclusive culture.

Sounds like you? Let's talk.

At Raintree, we’re not just shaping the future of therapy technology – we’re creating it. This is your chance to be part of something bigger, where your career will have game-changing, career-defining moments that propel you to new heights. We aim to be the best place for the best people, and we’re looking for ambitious, creative thinkers ready to make an impact. Whether you’re advancing AI solutions or enhancing user experiences, your work here will shape the future of therapy technology while advancing your career alongside dedicated professionals who are as committed to your success as you are. At Raintree, your ideas drive real change, your growth is limitless, and the work you do will touch millions of lives. Ready to ignite your career and leave a lasting legacy? Join us and be part of something extraordinary.

Our Core Values

We put our Clients First - We are Open and Honest - We are Disciplined, Yet Flexible

We love to Solve Problems - We are Committed to Greatness - We are a High Performance Team

U.S. Based Perks

Remote First

Paid Time Off/11 Paid Holidays/Year-End Holiday Break

Health, Dental, Vision, HSA/FSA,

401K with Company Match

Disability & Life Insurance

Employee Assistance Program

Paid Parental Leave

Raintree Systems provides equal employment opportunities to all employees and applicants for employment and prohibits discrimination and harassment of any type without regard to race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state or local laws.

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