Senior FULL-STACK / PLATFORM ENGINEER

We are seeking a senior full-stack/platform engineer to take ownership of an existing communications platform, rapidly assess its current state, resolve remaining critical issues, and bring it through production completion. ABOUT THE PLATFORM Stay Connected Plus is a communications platform designed to connect incarcerated individuals with family and friends outside. Inside members interact with the system by telephone through a voice-based IVR assistant, while outside members use the web and mobile applications to manage accounts, add prepaid credit, exchange messages, and receive live calls. The platform combines telephony, real-time voice, messaging, payments, mobile, web, and account management into one connected system. This is NOT a ground-up build. Substantial development has already been completed. The incoming developer will receive a detailed handoff document covering the system architecture, current state, known defects, prioritized work, and specific acceptance criteria. TECHNICAL ENVIRONMENT The platform includes: * Node.js / Express backend * React web application * React Native / Expo mobile apps * PostgreSQL and MongoDB * AWS infrastructure * GitHub Actions / CI/CD * Asterisk and Telnyx telephony * SIP / WebRTC calling * Voice IVR and speech services * Payment and prepaid-credit systems * Administrative tools PROJECT SCOPE The primary responsibility is to independently verify what currently works, correct what does not, complete the remaining development, and prove that the full platform works end-to-end in production. Key work includes: * Review the existing codebase and infrastructure and validate the current system state * Complete the production environment cutover from development * Migrate and reconcile production data safely * Verify real payment processing, including successful charges, declines, refunds, duplicate protection, and account-credit posting * Complete and verify two-way calling from the IVR to browser and mobile clients * Test and correct the Asterisk/Telnyx/IVR call flow, prompts, authentication, recording, and call handling * Complete voice-message recording and delivery * Correct shared-number and member-identification behavior * Remove outdated IVR instructions and legacy product behavior * Complete the required outside-member onboarding and inside-member setup flow * Test and complete the mobile application on real iOS and Android devices * Complete push and VoIP notification functionality * Resolve call-correlation and killed-app calling issues * Bring the admin console current with the latest telephony, billing, and shared-number model * Correct member-facing notification and data-feed issues * Restore and verify automated repository backups * Remediate exposed credentials and high-priority security findings * Resolve CI/CD and deployment workflow issues * Perform full regression, production acceptance, and clean-account end-to-end testing Existing completion claims must be independently verified. We are looking for an engineer who tests the actual running system and produces evidence of successful operation rather than simply reporting that code has been completed. PROJECT STRUCTURE This is a FIXED-PRICE, MILESTONE-BASED project. All required project work will be performed through funded milestones with clearly defined deliverables and objective acceptance criteria. Payment will be tied to successfully demonstrated milestone results. The first paid milestone will consist of an independent technical audit and baseline assessment of the existing platform. Subsequent milestones will cover implementation, remediation, production completion, testing, and final handoff. Applicants may propose an appropriate fixed price for the initial audit milestone and subsequent work based on the scope described below. TARGET COMPLETION: NO MORE THAN TWO WEEKS. The successful engineer must have substantial focused availability during this period. Week 1 should produce substantial measurable progress, including the technical audit, verified system baseline, resolution of critical launch blockers, and working end-to-end components. Week 2 should focus on remaining implementation, production cutover and verification, regression testing, final acceptance testing, documentation, and final handoff. WHO WE NEED This position requires a genuinely senior engineer capable of taking ownership of an unfamiliar existing system and troubleshooting across multiple layers. Strong experience should include: * Node.js / Express * React * React Native / Expo * AWS production infrastructure * PostgreSQL * CI/CD and GitHub Actions * Asterisk / SIP * Telnyx or comparable telecom carriers * WebRTC / real-time communications * Production debugging and deployment Experience inheriting and completing an unfinished or troubled production system is highly desirable. This is not suitable for a junior developer or someone who can only work within one part of the stack. WHEN APPLYING, ANSWER ALL OF THE FOLLOWING: 1. Describe a project where you inherited an existing unfinished or problematic system and brought it to production completion. 2. What hands-on experience do you have with Asterisk, SIP, Telnyx, WebRTC, or comparable real-time communications technology? 3. Describe your AWS production deployment and troubleshooting experience. 4. Describe your experience with Node.js, React, and React Native. 5. If you received the repositories, infrastructure access, and detailed developer handoff documentation on day one, what would you do during your first 48 hours? 6. How much focused availability can you commit during the next two weeks? 7. Can you work under milestone-based acceptance criteria where completion requires demonstrated working results rather than hours worked? 8. What fixed price would you propose for the initial technical audit milestone described below, and how much time would you require to complete it? PAID INITIAL TECHNICAL AUDIT — MILESTONE 1 The first paid milestone of the engagement will be a complete independent audit of the existing platform so that both parties have a verified baseline before additional implementation continues. The audit should cover: * Existing codebase and repositories * System architecture * Security posture and exposed credentials * AWS infrastructure * Production readiness * CI/CD and deployment pipelines * PostgreSQL and MongoDB databases * Asterisk, Telnyx, SIP, and WebRTC infrastructure * IVR functionality and call flows * Web application * Mobile applications * Payment and prepaid-credit functionality * Repository backups * Known defects * Technical debt * Overall system quality and launch readiness The developer will compare the running system against the existing handoff documentation and independently identify: * What is working correctly * What is partially complete * What is incomplete * What is broken * What presents a security or production risk * What must be corrected before launch DELIVERABLES FOR MILESTONE 1 The paid technical audit milestone must produce: * A verified system-state assessment * A written findings report * Identification and prioritization of critical defects and launch blockers * Security and infrastructure findings * A prioritized remediation and completion plan * Recommended sequencing for the remaining milestones * Identification of any material discrepancies between the existing handoff documentation and the actual running system Acceptance of the milestone will be based on delivery of the agreed audit scope and written findings. Applicants should state the fixed price and expected completion time for this milestone in their proposal. IMPORTANT Please do not submit a generic proposal. We are specifically looking for a senior engineer who can take ownership quickly, diagnose problems independently, execute across the stack, and prove that the complete platform works end-to-end in production. All required engineering, testing, auditing, implementation, and deliverable work will be performed through agreed funded milestones. Applicants are not being asked to perform unpaid project work as part of the application process.