Projects
7 coding projects that mirror Gnosis Pay's actual tech stack. Build these to deeply understand the architecture and create interview talking points.
Difficulty
Domain
Interviewer
SIWE Auth Server
Build a Go HTTP server implementing Sign-In with Ethereum (EIP-4361). Users connect their wallet, sign a nonce-bearing message, and receive a JWT. This is the exact auth pattern Gnosis Pay uses for their B2B2C partner API.
Swap Event Indexer
Build a Go service that listens for Uniswap V3 Swap events on Gnosis Chain, decodes them, and stores them in a PostgreSQL database. Exposes a REST API for querying swap history with filtering and pagination.
Safe Module Spending Policy
Build a Safe Module that enforces spending policies: daily limits per token, allowlisted recipients, and time-locked large transfers. This mirrors Gnosis Pay's core card spending policy architecture using Safe{Core} modules.
Payment Settlement Service (DDD)
Model a payment settlement service using Domain-Driven Design in Go. Handle the full lifecycle: authorization → clearing → settlement, with proper aggregate roots, domain events, and repository patterns. This directly mirrors Gnosis Pay's card payment backend.
Gasless Meta-Tx Relayer
Build a meta-transaction relayer service: users sign EIP-712 typed data off-chain, the relayer validates and submits the transaction on-chain paying gas on behalf of the user. Includes a Solidity forwarder contract and Go relay service. This is how Gnosis Pay enables gasless card top-ups.
Event-Driven Payment Processor
Build a complete event-driven payment processing system: on-chain events trigger domain workflows, which update state, emit domain events, and project read models. Combines blockchain indexing with DDD and event-driven architecture. This is the closest project to Gnosis Pay's actual backend architecture.
B2B2C Partner API Platform
Design and build a multi-tenant B2B2C API platform: partners (businesses) integrate via API keys, manage their end-users' cards, and track transactions. Includes tenant isolation, rate limiting, webhook delivery, and API versioning. This maps directly to Gnosis Pay's partner API product.