TheraLink

The Problem

Patients in Malaysia had no efficient way to find and book licensed Speech-Language Pathologists (SLPs). The process involved word-of-mouth referrals, phone calls, and manual scheduling. Therapists, on the other hand, lacked digital tools to manage their practice, availability, and client relationships.

The Solution

I solo-built TheraLink — a full-stack appointment marketplace connecting patients with speech therapists. The platform handles the entire journey from therapist discovery to session completion.

What I Built

As the sole developer on a client contract, I owned every layer of the system:

• Appointment Marketplace — Browse therapists by specialty, location, language, and availability. Book center visits, home visits, or virtual sessions.
• Token-Based Credit System — Patients purchase token packages (with bulk discounts) to book sessions. Automatic refund calculations based on cancellation timing.
• Calendly-Inspired Availability — Therapists set weekly recurring schedules with one-time overrides. Buffer time, minimum notice, and booking window rules.
• Guardian-Dependent System — Parents manage appointments for multiple children with shared credit balance but separate medical histories.
• Virtual Sessions — Google Meet links auto-generated for virtual appointments.
• Payment Integration — Billplz (Malaysian payment gateway) with webhook verification.
• Medical Records — AES-256-GCM encrypted patient medical history.
• Admin Panel — Therapist approval workflow, transaction auditing, content management.

Technical Architecture

Built on a strict 4-layer architecture: Presentation → API → Service → Repository.

• 72 RESTful API endpoints organized by resource
• 18 database models with Prisma + PostgreSQL
• 211 TypeScript files with full type safety
• Zod validation on all API inputs
• Snapshot system — Immutable copies of therapist data captured at booking time
• Transaction audit trail — Every credit change tracked with before/after balances

Stack

• Frontend: Next.js 15 (App Router), TypeScript, Tailwind CSS, shadcn/ui
• Backend: Next.js API routes, Prisma ORM
• Database: PostgreSQL
• Runtime: Bun
• Integrations: Billplz (payments), Google Meet (virtual sessions), Resend (email), Cloudinary (file storage)
• Security: NextAuth 5.0, AES-256-GCM encryption

The Impact

• 72 API endpoints powering the full marketplace
• 18 database models with enterprise-grade schema design
• 7 languages supported for multilingual matching
• Production-ready at 92/100 health score
• Live at theralink.my

Lessons Learned

Building TheraLink solo taught me the value of strict architectural discipline. The 4-layer separation (presentation → API → service → repository) kept the codebase maintainable even as it grew to 211 files. The snapshot system for appointment data was a non-obvious but critical decision — without it, therapist profile changes would silently corrupt historical appointment data.