Every number on the screen has to survive an audit.

We build the surfaces money moves across - order entry, reconciliation, lending, wallets. Eight decimal places for crypto and two for fiat, a session token that never reaches client JavaScript, and every figure reconciled before anyone is shown it.

OrdersBTC / EURLive

SideSizeLimitFilledState

Working2

Sell0.1250000057,480.0062%Partially filled

Buy0.0089000057,300.000%Open

Needs attention1

Buy1.2000000057,410.000%Rejected · margin

Done4

Buy0.0421875057,412.30100%Filled

Sell0.3000000057,950.000%Cancelled

Buy0.0150000057,120.55100%Filled

Sell0.0625000057,390.00100%Filled

Order ticket

BuySell

Size

0.04218750BTC

Limit price

57,412.30EUR

Total

2,422.08EUR

The market moved since you opened this ticket

Review the new total before it is sent.

Review and place

Reconciled with ledger09:41:07

Illustrative · order states a real book has, crypto at 8 decimals, fiat at 2

1.0Selected work

1.1

Trade Ledger

Lending platform for commercial credit teams. Origination, credit assessment and the data behind both.

Acquired by United Fintech
After delivery

1.2

Barclays

Internal banking tools with AI-assisted workflows and the integrations behind them, inside a tier-1 bank's existing systems.

1.3

Web3 wallet layer

Sign-In-With-Ethereum against a server-issued challenge, on-chain deposits tracked to confirmation, and a card on-ramp signed server-side.

3 funding rails

0 secrets in the browser

2.0Security model

The session token never reaches client JavaScript.

Every request goes through a server-only BFF of ~50 cookie-authenticated endpoints, so script running in the page has no token to read. The card on-ramp is signed on the server, deposits are tracked to confirmation, and a failing provider degrades to a valid empty shape the screen can still render.

Networkapp.example

POST204/api/bff/session

set-cookie: __Host-session; HttpOnly; Secure

GET200/api/bff/wallet/balances

cookie only, no Authorization header

POST200/api/bff/onramp/sign

signature computed server-side

> document.cookie

> localStorage.getItem('session')

null

app/api/bff/wallet/balances/route.tsTypeScript

01import { readSession } from '@/server/session'

02import { wallet, report } from '@/server/providers'

04export async function GET(request: Request) {

05 const session = await readSession(request)

06 if (!session) return Response.json({ items: [] }, { status: 401 })

08 try {

09 return Response.json(await wallet.balances(session.accountId))

10 } catch (error) {

11 report(error)

12 return Response.json({ items: [], total: '0.00' })

13 }

14}

DepositUSDC

250.00000000 USDC

Tracking to confirmation9 / 12

On-chainCard on-rampTransfer

Illustrative · ~50 server-only endpoints, 0 secrets in the browser

What it covers

Signed httpOnly session
Server-signed on-ramp
Sign-In-With-Ethereum

Three funding rails
Deposit confirmations
Empty-shape fallbacks

3.0In practice

What that means in practice

01Trading and order-entry surfaces, with the states a real book has
02Multi-currency money primitives - 8 decimals for crypto, 2 for fiat, reconciled history
03Token-broker BFF: ~50 server-only endpoints, session token in a signed httpOnly cookie
04Provider-agnostic integration layer - 10 domains, ~125 typed methods, repointable by env var
05KYC and identity: Sumsub and KYCAID, shipped
06Every handler degrades to a valid empty shape rather than collapsing the page

4.0Numbers

Typed integration methods: ~125
Server-only BFF endpoints: ~50
Secrets in the browser: 0
Funding rails, one account: 3

5.0Further reading

Go a level deeper

The web3 wallet layer, in fullHow the login, the three rails and the server-signed on-ramp fit together, on Dynamic Frontend.dynamicfrontend.com

Available · 2 slots · Avg reply 4h · NA, EU, AUS & REMOTE

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Dawid reads every one.

Trade LedgerFintech
Acquired by United Fintech
AI workflows and a new platform
BuxholmiGaming · our own platform
14 complete themes from one codebase
Nothing copied per brand
Operating IntelligenceiGaming · AI
10 source systems, one auditable answer
Handles risk, odds, and trading decisions in real time