The backend of a multichain DeFi protocol

In 2025, a team that runs decentralised finance vaults on several blockchains entrusted me with its backend and its infrastructure. I worked there as backend and infrastructure lead, freelance, and I carried it end to end, from scoping to production.

I set up the monorepo and the Google Cloud infrastructure in Pulumi (Cloud Run, BigQuery, KMS, IAM, Cloudflare web application firewall). The API, in NestJS and GraphQL, follows a hexagonal architecture. It computes each vault’s yields and deposited value from chain events, indexed across several networks. Services go out as Docker images on Cloud Run, behind Cloudflare’s firewall, in isolated environments from sandbox to production. I wrote the team’s infrastructure and authentication documentation.

Everyone joining the team had to be able to develop on a complete environment without touching anyone else’s. So I gave each person their own sandbox, created by a script from the infrastructure described in Pulumi.