Senior Engineer, Crypto Cards & Smart Contracts | Non-custodial Web3 Payments App
AlemX is a Web3 super app on Solana/USDC with a self-custody wallet and crypto cards for the US, EU, and global markets through multiple issuing partners. We are looking for a senior engineer who will take ownership of the entire card stack: from on-chain top-ups to card authorization and settlement.
Areas of Responsibility
- Full cycle of crypto cards: top-up from wallet, top-up, spending, returns, reversals, chargebacks
- Integration with multiple card issuing providers through a unified provider abstraction layer, so that changing the issuer takes weeks, not months
- Smart contracts for card top-ups and settlement (Anchor/Rust on Solana), including cross-chain bridging where the issuer does not support Solana SPL tokens
- Card program webhooks and real-time authorization logic: balance check, limits, velocity controls, idempotency
- Reconciliation between on-chain balances, issuer ledgers, and our internal records
- Non-custodial architecture: we are a technology operator and never hold user funds
- PR review and release sign-off for everything related to card cash flows (dual approval, SOC 2 controls)
Tech Stack
Python/FastAPI, Go, Anchor/Rust, Supabase (Postgres), Redis, GCP Cloud Run, embedded wallet provider, Helius RPC.
Must-Haves
- At least one live production crypto card or card issuing integration (provider, volume, your role)
- Deep understanding of card rails: authorization, clearing, settlement, reversals, disputes, interchange
- Production Solana smart contract experience (mainnet program link is mandatory)
- Experience moving stablecoins between networks (Solana, EVM, TRON) and understanding bridging risks
- Financial code discipline: idempotent webhooks, reconciliation, 80%+ test coverage for monetary logic
- Security first: secrets management, auth verification, fail-closed design
- Solo developer only. No agencies or subcontracting. Daily overlap with UTC+4
- Languages: Russian and English
Nice-to-Haves
KYC/KYB flows with card issuers, PCI DSS understanding, experience in a SOC 2 environment, anti-fraud for card spending.
Hiring Process
Paid 15-day trial on real card integration tasks. Followed by full-time employment: fixed monthly payment plus bonuses for launching cards into production. Remote work.
Application Questions (template answers will be rejected)
- What card issuing integration have you launched into production? Provider, flow, volume, your specific role.
- A user has USDC on Solana, but the card issuer only accepts USDT on an EVM network or TRON. Design the top-up flow, maintaining the non-custodial model. Where does it break?
- An authorization webhook arrived twice, and the user's on-chain balance changed between the two calls. How will you handle this?
How to Apply
Send your resume and answers to the three questions to Hr@alemx.com with the subject line: Crypto Cards Engineer | First Name Last Name. Emails without answers to the questions will not be considered.
