Frontend Developer — FusionPBX Custom Theme (Ongoing, Part-Time)

Frontend Developer — FusionPBX Custom Theme (Ongoing, Part-Time) About the Project We're building a modern modal-based UI theme for FusionPBX (an open-source VoIP/PBX platform). The goal is to replace FusionPBX's legacy multi-page edit forms with a single-page modal experience — tabbed sidebar navigation, AJAX save-in-place, inline data tables, and a clean design system. What's Already Built A custom modal engine (vanilla JS) that fetches FusionPBX edit forms, parses them, and re-renders content into a tabbed modal with AJAX submission. 13 module configurations (Extensions, Devices, Ring Groups, Destinations, Fax, Call Center Agents, IVR, Voicemails, Time Conditions, and more) A full CSS design system with BEM-style components, CSS custom properties, and responsive layout A global button system, data table transformation, boolean toggle conversion, password visibility toggles, and stacked/nested modal support What You'll Be Doing Refactor the code. Check for security issues manually. Handing back production ready code to our senior team. We need senior humans to inspect and manually read the code instead feeding to LLMs. Your job is to reduce the senior dev team time by being dependant on you for production ready code. Tech Stack Vanilla JavaScript (ES6+, no frameworks) — the modal engine is a single-class architecture with JSDoc annotations CSS (custom properties, BEM naming, no preprocessor) FusionPBX (PHP/PostgreSQL) — you don't need to write PHP, but you need to understand the HTML forms it generates SSH/SFTP for deployment to Ubuntu servers Git-based version control with manual versioning log Must-Have Skills Strong vanilla JS — DOM manipulation, fetch API, async/await, FormData, event delegation Solid CSS — specificity management, flexbox, responsive design, debugging cross-version quirks Comfortable reading server-rendered HTML and reverse-engineering form structures Experience working with legacy codebases and progressive enhancement Self-directed — you'll get a codebase audit, version history, and clear architectural patterns, but you should be able to investigate and fix issues independently Nice to Have Experience with FusionPBX theming or Smarty templates Working Arrangement Part-time, ongoing — estimated 10-20 hours/week depending on workload PS if you are the right person, possibility of working for our core dev team as our frontend developer part time or full time as we are currently pushing close to 4 x SAAS products.