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Hourly Freelance Java Developer Jobs in California

Software Engineer

Cerritos, CA ยท On-site

$110K - $130K/yr

... SQL, Java, JSP, Spring MVC, Javascript and Redis. โ€ข Troubleshoot issues, perform analyses and ... hourly rate range for this role. This takes into account the wide range of factors that are ...

... developer tooling across the software development life cycle (task management, source code ... Multiple factors are taken into consideration to arrive at the final hourly rate/ annual salary to ...

... freelance work and professional experience). * Excellent communication skills and be able to work in a cohesive team environment. * Proficient in Java and JavaScript programming. * Experience ...

Cloud Software Engineer II

Sylmar, CA ยท On-site

$81K - $141K/yr

... freelance work and professional experience). * Excellent communication skills and be able to work in a cohesive team environment. * Proficient in Java and JavaScript programming. * Experience ...

Cloud Software Engineer II

Los Angeles, CA ยท On-site

$81K - $141K/yr

... freelance work and professional experience). * Excellent communication skills and be able to work in a cohesive team environment. * Proficient in Java and JavaScript programming. * Experience ...

Redondo Beach, CA Salary: $110.00 USD Hourly - $120.00 USD Hourly Description: Role: Software ... Proficiency in additional programming or scripting languages such as C, Java, Python, or Perl.

Staff Engineer- Machine Learning

Palo Alto, CA ยท On-site

$90K - $230K/yr

Fluency in DevOps Concepts, Cloud Architecture, and Azure DevOps Operational Framework * Experience ... Multiple factors are taken into consideration to arrive at the final hourly rate/ annual salary to ...

Staff Engineer- Machine Learning

Palo Alto, CA ยท On-site

$90K - $230K/yr

Fluency in DevOps Concepts, Cloud Architecture, and Azure DevOps Operational Framework * Experience ... Multiple factors are taken into consideration to arrive at the final hourly rate/ annual salary to ...

Senior Staff Engineer

Palo Alto, CA ยท On-site

$130K - $260K/yr

... developer tooling across the software development life cycle (task management, source code ... Multiple factors are taken into consideration to arrive at the final hourly rate/ annual salary to ...

Fluency in DevOps Concepts, Cloud Architecture, and Azure DevOps Operational Framework * Experience ... Multiple factors are taken into consideration to arrive at the final hourly rate/ annual salary to ...

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Hourly Freelance Java Developer information

How much do freelance Java developers charge?

Freelance Java developers typically charge between $30 and $150 per hour, depending on experience, project complexity, and location. Rates can vary based on skills such as familiarity with frameworks like Spring or Hibernate, and whether the work is short-term or long-term. Many freelancers also offer fixed project rates for well-defined tasks.

How to get freelance work for a Java developer?

To find freelance work as a Java developer, create a strong online portfolio showcasing your projects and skills, and register on freelance platforms like Upwork, Freelancer, or Toptal. Building a network through professional communities and continuously updating your skills with relevant certifications can also increase your chances of securing projects.

What's a good hourly rate for a freelance programmer?

For an hourly freelance Java developer, rates typically range from $30 to $150 depending on experience, project complexity, and location. Highly experienced developers with specialized skills or certifications may charge higher rates, while those new to freelancing or in lower-cost regions may charge less.

Which pays more, C++ or Java?

For an hourly freelance Java developer, Java generally offers higher pay rates than C++, especially for roles requiring enterprise applications, web development, or mobile app development. C++ skills are often valued in systems programming, game development, and performance-critical applications, which can also command competitive rates. Overall, Java tends to have broader demand in freelance markets, potentially leading to higher earnings for Java developers with relevant experience.
What cities in California are hiring for Hourly Freelance Java Developer jobs? Cities in California with the most Hourly Freelance Java Developer job openings:
Frontend Systems Developer (contract)

Frontend Systems Developer (contract)

Atomic Machines

Emeryville, CA โ€ข Hybrid

$90 - $120/hr

Part-time

Posted 8 days ago


Job description

Atomic Machines is ushering in a new era of micromanufacturing with its Matter Compilerโ„ข technology platform. This platform enables new classes of micromachines to be designed and built by providing manufacturing processes and a materials library that are inaccessible to semiconductor manufacturing methods. It unlocks MEMS manufacturing not only for device classes that could never be produced by semiconductor methods, but also for entirely new categories. Furthermore, this digital platform is fully programmable in the way 3D printing is digitalโ€”but whereas 3D printing produces parts of a single material using a single process, the Matter Compilerโ„ข technology platform is a multi-process, multi-material system: bits and raw materials go in, and complete, functional micromachines come out. The Atomic Machines team has also created an exciting first deviceโ€”made possible only through the Matter Compilerโ„ข technology platformโ€”that we will be unveiling to the world soon.
Our offices are in Emeryville and Santa Clara, California.
About The Role

In this role you will help maintain and extend a web-based visual graph editor for manufacturing workflows. Users create and connect nodes representing materials/workpieces/tools and manufacturing steps (processes/inspections), validate the resulting workflow against catalogs and strict data contracts, and export a schema-compliant JSON representation for downstream tooling.

This role blends UI engineering with data integrity work. The editor must stay responsive on large graphs, preserve correctness (IDs, validation, export format), as well as support collaboration workflows through version control integrations.

This is a part-time, hybrid, freelance/contract role. Hours:

  • 1st 60 days: 20-40 hours per week
  • Ongoing: 10-20 hours (minimum) per week
What You'll Do
  • Build and maintain a React + TypeScript UI for a graph editor (node/edge creation, selection, multi-select, drag/drop, property panels)
  • Implement schema-driven validation and export (JSON Schema / AJV), ensuring stable, backwards-compatible outputs as schemas evolve
  • Improve performance and reliability for large graphs (rendering, minimizing re-renders, preventing UI jitter, safe persistence)
  • Support workflows around identity/ID rules, including ID generation, transformations on copy/paste/import, and "minting/locking" behaviors that freeze certain fields once finalized
  • Maintain integrations used in real production workflows:
    • GitLab API (branching, committing files, MR workflows)
    • Methods API (catalog sync, offline fallback, validation that blocks pushes when API is down)
    • Authentication (Okta)
  • Ship small-to-medium features end-to-end: UI, state changes, validation, tests, and docs
  • Triage bugs from real users (manufacturing/process engineers), reproduce quickly, and implement safe fixes
  • Add/maintain unit tests (Jest + TS) around tricky logic (ID transformation, export validation, API sync behavior)
  • Keep the build/lint/test pipeline healthy (Vite, TypeScript, ESLint, Jest) and handle dependency upgrades carefully
  • Collaborate asynchronously with a cross-functional team (process, production, AI) through clear PRs, strong commit hygiene, and pragmatic technical decisions
  • Tools/Stack You'll Work With: React 18, TypeScript, Vite, Tailwind CSS, ReactFlow, AJV (JSON Schema), Jest, ESLint, GitLab API, OpenAPI, Okta
What You'll Need
  • Experience building complex, stateful UI systems (not CRUD/dashboard apps)
  • Strong React + TypeScript with state management + performance optimization
  • Experience with graph/diagram editors or similar interaction-heavy UIs
  • Experience with large in-memory data + UI/data synchronization
  • Experience with validation systems + deterministic outputs (schema, exports)
  • Strong debugging in complex systems + ability to explain tradeoffs
  • Experience leading complex, ambiguous problems across cross-functional teams with multiple stakeholders
Bonus Points For:
  • Manufacturing background (MES, process planning, CAD/CAM adjacent tooling, "recipes/methods/catalog" concepts)
  • JSON Schema / AJV experience and comfort with strict data contracts
  • GitLab API experience, auth systems (Okta/OIDC), or "internal tool" deployment constraints
Hourly Rate Range
$90โ€”$120 USD