JohannAvramov

Context

Open-access platform for heritage sciences (archaeology, history, conservation): PDF publication submission, search through the PACTOLS thesaurus, co-author collaboration and subscriptions.

What I built

Full rewrite of a platform already in production with 1,500 accounts created: moving from Angular, Express and MongoDB to Next.js, NestJS and PostgreSQL, with a progressive data migration.

Technical points

• ›Progressive data migration from MongoDB to PostgreSQL, with no downtime for the platform in production.
• ›Plagiarism detection through the Copyleaks API: PDF submission, asynchronous results received over a webhook with a verified HMAC-SHA256 signature, a state machine exposed to the front end, and administrator notification for manual review. Integrated in sandbox mode.
• ›Graceful degradation of the third-party service: with no API key the scan is marked as skipped, on a network error it is marked as failed, and the publication upload succeeds in both cases.
• ›Search indexed on the PACTOLS thesaurus, and co-author management on every submission.

Context

Pool maintenance professionals track their clients, their jobs and their invoicing across paper notes, messaging apps and spreadsheets. Nothing is connected, and client history gets lost.

What I built

Responsive web application for pool professionals: a multi-tenant SaaS covering clients, pools, jobs, stock, products, accounting and invoicing, with Stripe subscriptions.

Technical points

• ›Multi-tenant model with per-company data isolation.
• ›Stripe subscriptions and billing wired into the job lifecycle.
• ›Quote and invoice, accounting, stock, supplier and employee tracking modules.
• ›Form validation with Zod schemas and react-hook-form, Recharts dashboards and Vitest tests.
• ›OpenTelemetry instrumentation and performance monitoring.

Context

Airsoft clubs manage their members, field bookings, membership fees and inventory by hand, across spreadsheets and messaging apps.

What I built

A single platform bringing together member management, slot booking, automated invoicing and QR code access control, spread across eighteen functional modules.

Technical points

• ›Multi-tenant security enforced at the database level: PostgreSQL Row Level Security policies on Supabase, in a dedicated migration.
• ›Nine business Edge Functions: slot booking, PDF invoice and QR code generation, member invitation, inventory management, scheduled reminders and email sending.
• ›Six versioned SQL migrations to evolve the schema.
• ›Custom build guardrails, blocking in development and at build time: mock data detection, Supabase configuration validation and environment checks.

Context

During pregnancy, checking whether a food is safe means cross-referencing scattered medical sources. That is not usable standing in a supermarket aisle or in front of a restaurant menu.

What I built

A mobile app that identifies ingredients from a photo of a dish or a restaurant menu, then returns a verdict matched to the pregnancy profile: green, orange or red, with an explanation and a per-ingredient breakdown.

Technical points

• ›Ingredient recognition and risk analysis through the Google Gemini API, with two input modes: photo of a dish, and restaurant menu.
• ›Robust model calls: three attempts with progressive backoff, retries limited to 429 and 5xx responses, fallback to a secondary model, recovery of truncated JSON responses and an image size cap.
• ›Verdict computed from the user profile: trimester, toxoplasmosis immunity, allergies and how the food was prepared.
• ›Migration from Supabase to Firebase: authentication, Firestore, storage and Cloud Functions.
• ›Subscriptions handled through RevenueCat, Google and Apple sign-in, Jest tests on the analysis functions.