maxkravchuk

Sole engineer owning the full on-chain data indexing layer for a production DeFi protocol — from architecture and pipeline design through CI/CD, deployment, and runtime monitoring. Designed and shipped event-driven data pipelines processing high-volume blockchain events, aggregating raw on-chain storage into derived DeFi state (spot prices across multiple pool types, reconciled account balances, multi-pool position data) consumed by the protocol frontend and analytics teams. Built the indexer service in TypeScript on PostgreSQL, with pg-boss and Bull powering background jobs and queue workloads; used the Subsquid (SQD) framework as the chain-data ingestion layer. Implemented zero-downtime upgrade and historical-resync patterns by deploying indexer instances in parallel and switching traffic between them. Owned CI/CD end-to-end: automated build, environment promotion, deployment, and runtime monitoring via GitHub Actions and Docker Swarm. Delivered structured GraphQL and REST APIs as the protocol's primary data interface to frontend and analytics consumers.

Built and owned the backend for a blockchain-based social platform serving both a web blog application and a mobile chat client. Designed a hybrid on-chain/off-chain data system: a unified data model and GraphQLAPI serving both indexed on-chain entities and off-chain entities created directly through the API, letting the protocol use the chain selectively for high-value content while keeping ephemeral content cheap. Built a multi-source event pipeline funneling on-chain events, web app actions, and mobile client writes into a single Redis/Bull queue as the sole data provider to a NestJS + PostgreSQL core service, with deduplication and state-transition logic to merge on-chain and off-chain representations of the same entity. Shipped an optimistic write path for the chat client (instant render via GraphQL WebSocket subscriptions, reconciled to persisted state once the on-chain event was indexed) and a moderator approval workflow over off-chain content (review queue with approve/reject for posts, comments, and authors; status transitions surfaced to clients in real time). Built stake-weighted aggregation services on top of the unified data layer: a rewards engine combining engagement signals (likes, replies, comments) across on-chain and off-chain content weighted by on-chain token stake, and a feed ranking service combining on-chain stake, on-chain activity, and off-chain engagement into a unified score for the blog feed.

Built self-hosted blockchain indexers for chains in the Subsquid customer base. Contributed feature work and bug fixes to the core open-source SQD framework. Provided technical support to framework users and partner teams integrating SQD into their stacks.

Built the client-side application for the HydraDX DEX trading platform using Vue 3 and the Polkadot.js API. Integrated wallet-based authentication for secure access to on-chain operations. Contributed to a $1.5M token claim distribution flow, delivering the client-side path used by end users.

Concurrent part-time contracts and Upwork freelance work across e-commerce, B2B marketplace, and media platforms. Servv Inc. — Shopify e-commerce integrations using React.js, Redux, Vue.js, and the Shopify and Zoom APIs; authentication flows via Shopify App Bridge. Cignal TV (onenews.ph) — Single-page applications for a national news platform using Nuxt.js and a .NET API backend; deployment via AWS EC2, Docker Compose, and Elastic Beanstalk. bevazar.com (Germany) — B2B marketplace using Nuxt.js, Algolia search, Mangopay payments, and Google serverless services. tecorio.parts (Germany) — B2B marketplace using Vue.js / Nuxt.js, Firebase, and Algolia. News Deeply — Frontend feature work on a Ruby on Rails application, including Stripe payment flows. Upwork Freelance — 40+ projects, 4,000+ billed hours, 5-star rating across React, Vue, Nuxt, Angular, and React Native engagements.