WeWalk
Node.js · TypeScript · Express · Sequelize · PostgreSQL · Firestore · Redis · GCP Cloud Run · Vue · Angular · BLE
WeWalk makes a smart cane and companion app used by visually impaired people in more than sixty countries. I have been the sole backend engineer on the platform since January 2024: 27,000+ registered users, roughly 590 REST endpoints across 52 service modules, and every one of the 1,679 commits made to the core API in that period. The codebase dates back to 2020 and had passed through a few hands before I took it over.
The largest piece of work was moving the entire production stack from a self-hosted Rancher/Kubernetes cluster to Google Cloud Run, Cloud SQL and Firestore - reconstructing system state from backups, since working access to the original environment was no longer practical by then. A separate AWS-to-GCP move shipped with zero forced client updates: I built a Lambda-to-Cloud-Run WebSocket proxy that kept the existing mobile endpoints alive, which matters when your users cannot be casually asked to update an app they rely on to navigate.
Beyond the migrations, I designed the SKU/feature entitlements engine (rules, campaigns, warranty periods, Zoho CRM serial-number-driven grants), integrated the Apple App Store Server API and Google Play Billing with subscription reconciliation, and built BLE OTA firmware distribution and cane telemetry ingestion - 102-byte BLE snapshots every ~10 seconds into a partitioned time-series table. After an incident where entitlement changes could not be attributed, I added a trigger-based PostgreSQL audit trail with monthly partitioning and JSONB before/after diffs.
Highlights
- Self-hosted Kubernetes → GCP Cloud Run migration, state rebuilt from backups
- AWS → GCP with zero forced client updates via a WebSocket proxy
- Schema grown from 34 to ~95 tables across 174 migrations
- WeAssist remote-assistance console (Angular 18 + Zoom Video SDK) built from the first commit