edtech-billing-core: Race-Safe Billing on PostgreSQL
Append-only ledger · Deadlock-free lock order · Verified payment webhooks · Open source
TypeScript, Python, PostgreSQL. Payments, auth and integrations.
Sole backend engineer behind a production operations platform (CRM + LMS) for an online exam-prep school, and designer of high-concurrency transaction cores.
Baku, UTC+4 · full overlap with EU hours, mornings with US East · Remote contract, 30 h/week, open to more.

Work
Billing, payments and auth that have to stay correct under concurrency.
Append-only ledger · Deadlock-free lock order · Verified payment webhooks · Open source
Production monorepo for an online exam-prep school · Sole engineer · Since March 2026
Currently
Building an LMS/CRM for a multi-branch test-prep center in Baku as solo developer.
Structural Isolation Trust Boundary · 0/15 Hardened ASR · Alpaca × lablab.ai Hackathon
Handled enrollment intake, payment reminders and FAQ for an exam-prep school, running on a VPS.
Backend
Data
AI
Infra & Testing