Senior Full-Stack Developer (PHP & React) — OnTheGoSystems (Remote)

OnTheGoSystems is hiring a Senior Full-Stack Developer (PHP & React) to help maintain and evolve WPML and other products used by over 1.5 million websites. This remote role suits developers who write clean architecture, value automated tests, and want to make a measurable impact on a stable, self-funded company.

Why join OnTheGoSystems

Since 2008 OnTheGoSystems has grown into a profitable, remote-first company known for WPML — the #1 multilingual plugin for WordPress. You’ll join a diverse, supportive team, work on products that matter, and enjoy a culture that prioritises growth, wellbeing and meaningful work.

What you’ll do (Senior Full-Stack Developer)

• Design, develop and maintain core product features in PHP and React.
• Collaborate with developers, QA and support to deliver reliable, high-quality functionality.
• Write and maintain automated tests (PHPUnit, E2E) to protect product stability.
• Improve code architecture, review peers’ work, and help drive technical decisions.
• Investigate and resolve performance or reliability issues affecting users at scale.

What makes a great fit

• Strong experience with PHP and modern React (including Redux or equivalent state management).
• Deep understanding of databases, design patterns and scalable code architecture.
• Passion for automated testing and CI (unit tests, integration/E2E tests).
• Ability to communicate clearly in a distributed, asynchronous team.
• Product-minded — you care about user impact and long-term code health.

Apply

Ready to apply? Use the official job listing and submit your application here: CLICK HERE TO APPLY — Senior Full-Stack Developer (PHP & React).
For convenience, the word EMAIL is also linked to the application page.

Sample CV / Resume

Sample Cover Letter

Sample Motivation Statement

Sample Email to Apply

Interview Preparation Guide — Senior Full-Stack Developer

Role-specific questions (8–12)

• Describe a complex PHP architecture decision you made and its impact.
• How do you structure React components for maintainability in a large plugin?
• Explain a time you fixed a performance issue on a high-traffic site.
• What testing strategy do you use for plugins and frontend components?
• How do you approach backwards compatibility in WordPress plugins?
• Describe an occasion when you led a code rework or refactor.
• How do you prioritize bug fixes vs. feature work?
• Share how you mentor junior developers in code reviews and testing practices.

Suggested talking points / answers

• Use a clear problem → action → result structure. Quantify outcomes (performance %, reduced errors, time saved).
• Mention specific tools (PHPUnit, E2E frameworks) and CI pipelines you implemented.
• Explain trade-offs you considered (backwards compatibility vs. new APIs) and why you chose a path.
• Describe how you improve code readability and onboarding through docs and examples.
• Show collaborative examples: working with support to reproduce bugs, or with product to scope features.

General interview questions (5–7)

• Tell us about your background and career highlights.
• Why OnTheGoSystems and why WPML?
• What are your strengths and areas for development?
• Describe a challenging team situation and how you handled it.
• How do you keep learning and stay current with web technologies?

Do’s & Don’ts

Do’s

• Do prepare concrete examples with metrics and outcomes.
• Do demonstrate testing experience and CI/CD knowledge.
• Do show code architecture thinking and trade-offs.
• Do highlight collaboration with support, QA and product teams.
• Do bring links to code samples, tests or public repos where possible.
• Do ask thoughtful questions about the product, team and release process.

Don’ts

• Don’t answer only at a high level—include specifics and outcomes.
• Don’t downplay testing or quality practices—these matter at scale.
• Don’t criticise previous employers—focus on learning and outcomes.
• Don’t promise unrealistic timeframes for large refactors without caveats.

Preparation checklist

• Review WPML product basics and common integration points with WordPress.
• Prepare 3–4 STAR stories with metrics (performance, uptime, bugs reduced).
• Have code samples or a small demo repo ready to share.
• Ensure your development environment and recordings (if required) work correctly for remote interviews.
• Read the job listing and prepare questions about team structure and expectations.

Extra pro tips

• When discussing trade-offs, show you consider users on large and small sites.
• Talk about observability—how you detect regressions and monitor production.
• If asked about weaknesses, describe a mitigation plan you implemented.

Tips to Work With — Senior Full-Stack Developer

1. Overview

Role definition: a Senior Full-Stack Developer builds and maintains features across backend (PHP) and frontend (React), ensures reliability via tests, and shapes long-term architecture. Core responsibilities include feature development, maintenance, testing, performance tuning and mentoring.

2. Step-by-step process (how the role is executed)

Typical workflow (text flowchart):

• Receive ticket or roadmap item → Scope & design solution (architecture and tests).
• Implement backend API or PHP change; add unit tests.
• Implement React components and integration tests.
• Run CI, fix test failures, perform code review.
• Merge, deploy to staging and run E2E regression tests.
• Monitor post-release for errors and iterate as needed.

Tools, documents and platforms

• PHP, Composer, WordPress environment (local & staging).
• React, Redux (or Context), build tools (webpack/Vite), and component libraries.
• Testing frameworks: PHPUnit for PHP, Jest/Cypress/Playwright for frontend & E2E.
• CI/CD (GitHub Actions, GitLab CI, etc.), Docker for reproducible environments.
• Issue tracker (GitHub/GitLab), code review tools and documentation (MD files).

3. Illustrative example (Problem → Solution)

Problem: A large multisite installation experiences slow admin pages when large translation tables are queried.

Solution: Implement paginated queries and add appropriate DB indexes, move heavy joins into a background job, and cache results for common queries. Add unit and integration tests to cover edge cases. Result: admin page load improved from 6s to 1.8s and support tickets decreased substantially.

4. Learning & Resources (backlinks)

Recommended upskilling resources:

• freeCodeCamp — hands-on frontend & backend tutorials (free)
• Coursera — Full-Stack React specialization (professional certificate)
• edX / Top universities — advanced web development and architecture programs

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