Clear scope · Clear deliverables · Remote B2B

Custody reviews that leave an evidence trail.

I work with custodians, exchanges, stablecoin issuers, tokenization platforms, banks, and DeFi lending and vault teams that hold or move digital assets for clients. We agree the scope and the pricing model in writing before work begins: a fixed fee when the scope is clear, or a day rate when it is still taking shape.

Read-only by default. No access to keys or client assets. Everything learned about your systems remains under NDA.

Describe your setup Read field notes

Engagements

Custody architecture review2 weeks · fixed fee or day rate: I review key management and signing, deposit detection, transaction lifecycle, reorg handling, ledger integrity and client-asset segregation. You receive a written report with severity-ranked findings, sequenced remediations and a walkthrough.
Evidence-readiness assessment1-2 weeks · fixed fee or day rate: I assess how internal positions reconcile against chain state and map the gaps against safeguarding, record-keeping and recovery expectations. You receive a reconciliation policy and a reproducible evidence format an auditor can use.
Lending & vault review1-2 weeks · fixed fee or day rate: I review share and NAV accounting, deposits and redemptions, liquidations, interest accrual, oracles and fees in lending markets and ERC-4626 / ERC-7540 vaults. You receive severity-ranked findings with reproduction paths and fixes, a fix review, and 30 days of onchain share-price monitoring after launch.
Fractional custody engineeringRetainer · limited capacity: Ongoing architecture decisions, code review of signing and ledger paths, incident support and build-vs-buy guidance for teams that need senior custody judgment without a full-time hire. I take one retainer engagement at a time.

Fit

Good fit

A live or inherited system holds client assets.
An audit, launch, incident or architecture decision created urgency.
You want findings your engineers can verify and act on.

Not a fit

Speculative token promotion or anonymous launch support.
An open-ended build with no owner, scope or decision deadline.
Any engagement requiring custody of production keys or funds.

How it works

1. Scope: A 30-minute call establishes the system boundary and why the work matters now. You then receive a one-page scope with deliverables, access needs and pricing, fixed or day rate, whichever fits the work. If the scope is still unclear, we start with a short paid discovery at the day rate.
2. Evidence: I work from read-only code, architecture documentation and operating evidence. Assumptions and unavailable evidence are explicit rather than silently filled in.
3. Handoff: The report, policy and evidence formats are yours. They are written so an engineer, auditor or regulator can use them without me in the room.

Start with the problem, not a sales deck.

Email contact@maciejlewandowski.dev with a short description of your setup and what prompted the request, or reach me on LinkedIn. I reply within one business day.