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Freelance Senior Backend Developer Jobs in California

Senior Backend Engineer

San Jose, CA · On-site

$180K - $225K/yr

As a Senior Backend Engineer , you'll drive backend architecture, scale platform services, and ... Work with DevOps/SRE on CI/CD, deployment automation, and scalability * Contribute to architecture ...

Senior Backend Engineer

Alameda, CA · On-site

$150 - $230/hr

We need a senior backend engineer with 5+ years of experience building production systems who has deep expertise in security, cryptography, and cloud infrastructure. You should be comfortable owning ...

New

They are seeking a Senior Backend Engineer who will take ownership of program vision and execution, design and maintain web applications, and manage the software development process. Responsibilities ...

As a Senior Backend Engineer on the Xumo Software Engineering Team, you will play a key role in building and optimizing the backend infrastructure that powers our video streaming services. This ...

Our platform empowers developers by providing secure, reliable access to LLMs and adjacent services, and we're looking for a Senior Backend Engineer to help us build rock‑solid guardrails and ...

As a Senior Backend Engineer on the Xumo Software Engineering Team, you will play a key role in building and optimizing the backend infrastructure that powers our video streaming services. This ...

Sr. Backend Engineer - Xumo

Irvine, CA · Remote

$141K - $189K/yr

As a Senior Backend Engineer on the Xumo Software Engineering Team, you will play a key role in building and optimizing the backend infrastructure that powers our video streaming services. This ...

They are seeking a Senior Backend Engineer to join their Core Engineering Team, focusing on enhancing document workflows and building new systems to improve user experiences. Responsibilities : • ...

Sr. Backend Engineer - Xumo

Irvine, CA · On-site

$142 - $189/hr

As a Senior Backend Engineer on the Xumo Software Engineering Team, you will play a key role in building and optimizing the backend infrastructure that powers our video streaming services. This ...

Senior Backend Engineer

San Francisco, CA · On-site

$175K - $275K/yr

As a Senior Backend Engineer , you will design, build, and deploy the backend services that power our creative brainstorming and creation products. You will work with web and video standards to power ...

They are seeking a founding Senior Backend Engineer to design, develop, and ship robust backend systems that deliver exceptional value to their members, working closely with founders, engineers, and ...

About this role We're looking for a Senior Backend Engineer to join our Core Engineering Team , which powers some of the most essential experiences at Scribe: document viewing and editing, embedding ...

New

We are looking for a senior backend engineer to own the backend systems that make that possible. The role You will work on the backend systems that power Slope's embedded credit, payments and ...

We are looking for a senior backend engineer to own the backend systems that make that possible. The role You will work on the backend systems that power Slope's embedded credit, payments and ...

New

As a Senior Backend Engineer, you will design clean APIs, build scalable services, and maintain ... DevOps best practices • Built scalable data pipelines that have facilitated large-scale event ...

Senior Back End Developer

San Diego, CA · On-site

$127K - $166K/yr

Company Description Jobs Bridge Inc is among the fastest growing IT staffing / professional services organization with its own job portal. Jobs Bridge works extremely closely with a large number of ...

Senior Backend Engineer

Palo Alto, CA · On-site

$100K - $160K/yr

We are looking for a senior backend engineer to join our small team as we continue building out our product and deploy it to some of the largest insurance carriers in the world. * Founded 2019

As a Senior Backend Engineer, you will design and scale AI-driven detection and response workflows, working with a small team to create modern security experiences that keep people and property safe.

Showing results 21-40

Freelance Senior Backend Developer information

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Infographic showing various Freelance Senior Backend Developer job openings in California as of August 2026, with employment types broken down into 100% Full Time. Highlights an 100% In-person job distribution.

Senior Backend Engineer

FlexAI

San Jose, CA • On-site

$180K - $225K/yr

Full-time

Re-posted yesterday


Job description

About FlexAI
Build and Deploy AI the right way, anywhere.
The FlexAI Compute Infrastructure Platform provides an "end-to-end AI compute layer" for running and managing workloads across any cloud, any GPU, and any deployment model (public, hybrid, or on-prem). It brings together "1-click simplicity" for users with "enterprise-grade orchestration, security, and automation" under the hood.
Founded by Brijesh Tripathi, who bring experience from Nvidia, Apple, Tesla, Intel and Zoox, FlexAI is not just building a product - we're shaping the future of AI. Our teams are strategically distributed across Silicon Valley and Bengaluru, united by a shared mission: to deliver more compute with less complexity.
If you're passionate about shaping the future of artificial intelligence, driving innovation, and contributing to a sustainable and inclusive AI ecosystem, FlexAI is the place for you !
Role Overview
FlexAI is looking for a Senior Backend Engineer (Infrastructure & AI Platform) with deep Golang expertise to architect and build the core backend systems powering our next-generation AI compute and PaaS platform. This role sits at the intersection of distributed systems, cloud infrastructure, and AI platform engineering - enabling large-scale model training, inference, and orchestration across heterogeneous compute. This is not a traditional backend role; you will be building platform-grade systems that support AI runtimes, scheduling, resource orchestration, and multi-tenant cloud infrastructure.
As a Senior Backend Engineer, you'll drive backend architecture, scale platform services, and build high-performance infrastructure components that power AI workloads in production environments - influencing how the platform evolves from Beta to enterprise-grade deployment. Expect high ownership and technical autonomy in a research-driven, deep-tech environment - not SaaS CRUD apps.
This position is In-Person and located at our San Jose, CA Office.
What You'll Do
Core Platform & Infrastructure Backend:
  • Architect and develop high-performance Golang services for FlexAI's AI PaaS and infrastructure platform
  • Build internal APIs powering model deployment, job scheduling, and compute lifecycle management
  • Develop components interfacing with GPU/compute infrastructure and AI runtimes

Distributed Systems & Scalability:
  • Design and scale microservices and event-driven systems for high-throughput AI workloads
  • Optimize for low latency, high concurrency, and fault tolerance
  • Implement service-to-service communication (gRPC/REST, message queues, async pipelines)
  • Drive reliability, observability, and resilience across services

AI Platform Integration:
  • Collaborate with AI/ML and Runtime teams to integrate systems with training pipelines, inference infrastructure, experimentation workflows, and dataset/artifact management
  • Enable orchestration across cloud and on-prem environments
  • Build abstractions that simplify AI infrastructure consumption

Cloud-Native & Platform Engineering:
  • Design cloud-native, Kubernetes-native services
  • Work with DevOps/SRE on CI/CD, deployment automation, and scalability
  • Contribute to architecture decisions for multi-region, multi-cloud infrastructure
  • Improve monitoring, logging, and diagnostics

Technical Leadership:
  • Lead architecture reviews and set engineering standards
  • Mentor engineers and guide complex problem-solving
  • Drive long-term roadmap for backend infrastructure and AI platform capabilities
  • Partner with Product, Runtime, and Infra leadership to translate requirements into scalable systems
Tech Stack (Indicative):
  • Languages: Golang (Primary), Python (Secondary)
  • Infrastructure: Kubernetes, Docker, Cloud (AWS/GCP/Azure)
  • Architecture: Microservices, gRPC, Event-driven systems
  • Data: SQL + NoSQL databases, caching, streaming systems
  • Observability: Prometheus, Grafana, OpenTelemetry (or similar)
What You'll Need to Be Successful
Core Engineering:
  • 5+ years of Backend or Infrastructure Engineering experience
  • Expert-level proficiency in Golang (must-have, heavy hands-on)
  • Strong experience building production-grade distributed systems
  • Proven track record on infrastructure platforms, PaaS, or deep-tech systems

Infrastructure & Systems:
  • Deep understanding of cloud-native architectures and containerized environments
  • Strong experience with Kubernetes, Docker, and cluster orchestration
  • Familiarity with compute scheduling, resource management, or platform runtimes is a strong plus

Databases & Data Systems:
  • Experience with distributed databases (PostgreSQL, Cassandra, DynamoDB, etc.)
  • Strong understanding of caching, queues, and streaming systems (Redis, Kafka, etc.)

AI / Platform Exposure (Highly Preferred):
  • Experience on AI/ML platforms, model infrastructure, or data platforms
  • Familiarity with ML pipelines, inference systems, or GPU-backed workloads
  • Exposure to PyTorch, TensorFlow infrastructure, or model serving systems is a plus

Ideal Candidate Profile (Who Will Thrive Here)
  • Infra-first backend engineers (not just API developers)
  • Background in AI infra, cloud platforms, developer platforms, or deep-tech systems
  • Strong systems thinkers who enjoy low-level performance, scalability, and architecture challenges
  • Startup-minded builders comfortable in ambiguous, high-ownership environments

What We Offer
  • Competitive salary and benefits package
  • Work on cutting-edge AI infrastructure
  • Build products used by developers and enterprises
  • High ownership, fast execution, real impact
  • Collaborative, high-caliber team

The pay range for this role is:
180,000 - 225,000 USD per year (US)