Can a transfer be sent twice?
Every transfer request carries its own unique reference, so a retry after a timeout finds the original transfer instead of creating a new one.
Fintech · custody
Fireblocks custody transfers you can trace from request to ledger
Your partners want to know how a transfer is approved, signed and recorded, and today the answer is split between the Fireblocks console, your database and someone's memory. We wire Fireblocks into your platform so every transfer starts under your rules, every callback is matched to its request, and custody balances reconcile to your ledger.
Typical lengthweeks
From€10,000
Built onFireblocks, Double-entry ledgers, Webhooks
When teams call us
What usually triggers the work
It usually starts with growth or a review. You are launching or scaling crypto or stablecoin products, the EU's crypto-asset rules (MiCA) now apply to your business, or a partner bank asks how a transfer is approved, signed and recorded.
Without one path from request to ledger, transfers get started by hand in the console, callbacks update the wrong record or none at all, and custody balances drift from what customers see. Customers notice a stuck withdrawal first; an auditor notices the balances that don't match.
What we deliver
In your repository, demoed every week
- Fireblocks vaults, policies and transfer flows started from your platform under your rulesYour platform creates vault accounts and starts transfers through the Fireblocks API, inside the policies you set in Fireblocks. You can see which rule allowed each transfer.
- Every callback matched to the request that caused itEach transfer carries your own reference, and every status callback is verified and matched back to it. You can follow any transfer from the customer's request to its final status.
- Custody balances reconciled to your ledger dailyVault balances are compared with the ledger every day, and any difference raises an alert. You get a daily report of what matched and what didn't.
- Operations tools for approvals, stuck transfers and incidentsOne back-office view for transfers waiting for approval, stuck or failed, with the safe next step for each. Every action taken there is logged.
How it holds up
The questions a reviewer will ask, answered in the build
What if a callback is lost?
Callbacks are stored before they are processed and can be replayed. Transfers without a final status are checked against Fireblocks, so none is left “probably done”.
Who approved this transfer?
Every transfer records who asked for it, which rule or person approved it and what the provider reported, ready for a partner's or an auditor's sample check.
Proof
Where we have done this before
Banking orchestration
One system of record across Sumsub, Fireblocks, a ledger and banking-as-a-service partners, in production for a European payment platform.
Built on
- Fireblocks
- Double-entry ledgers
- Webhooks
Often built together: ledger and reconciliation and KYC and KYB onboarding.
Price
What it costs
Custody integration builds start from €10,000 (£8,700 · $11,500). The price depends on how many assets and transfer flows you support and how much of your current set-up we can keep. typical duration
Most teams start with the Readiness Review: €4,900 (£4,250 · $5,500), fixed, 7 working days, with every fix priced. If you then build with us, the fee is credited to the build.
Questions
Before you book
Do you build on Fireblocks only?
Fireblocks is the custody platform we have built on in production, so it is where we are fastest. The same patterns, your own transfer states, matched callbacks and daily reconciliation, apply to other custody providers; we read their documentation first and tell you plainly what would be new to us.
Can you work alongside our Fireblocks account team?
Yes. Your Fireblocks contract, workspace and policies stay yours. We work in your workspace with the access you give us, and bring your Fireblocks contacts in when a question is about their product rather than your integration.
What about MiCA?
MiCA sets the EU rules for crypto-asset service providers, including how clients' assets are kept apart and recorded. We don't advise on your licence; your lawyers and compliance team do. We build the records and controls they ask for: clients' balances kept separate in the ledger, daily reconciliation and an audit trail of every transfer.
Who owns the code and the IP?
You do, from the first commit. We work in your repository and your accounts, and the contract assigns the IP to you in the present tense, not at some later date.
Who will actually work on our project?
The engineers named in the proposal, and you meet them before you sign. A key-person clause means nobody is swapped without your written consent.
How do time zones work for a UK or US team?
We work on Lisbon time, which is the same clock as London: Mon–Fri, 08:00–18:00 UK time. That leaves about four working hours a day in common with the US East Coast. You get a demo of working software every week and a short written update every working day.
What contracts do you sign?
A master services agreement with a statement of work for each project, or your own paper if you prefer. A mutual NDA before we see anything, and a GDPR data processing agreement. US clients get a W-8BEN-E from us. Which law governs the contract is answered on Contracts & security.
How do we pay?
The fixed-price first step is paid upfront. Builds are billed by milestone, after you have seen the work running. Monthly care, if you want it, is billed at the start of each month. We invoice in euros, pounds or dollars.
Free 30-minute call
Tell us what has to work, and by when
You talk to an engineer who would work on it, not a salesperson. You leave the call knowing what it would take and what the first step costs, or we tell you that you don't need us.