Several systems describe the same transaction
Your provider says paid, your app says unpaid, and refunds, upgrades and failed cards do strange things in between.
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Custom software · Blockchain & fintech integrations
Connect financial workflows without losing the audit trail
For teams moving money or financial records through their product: card issuing, bank linking, subscriptions, crypto market signals, investigation records. We map every path a transaction can take (failed, retried, refunded, disputed), build the integration with signed webhooks and idempotency keys, and log every event, so the next “what happened to this payment?” has an answer. One recent build: a payments platform for US political campaigns on Lithic and Plaid, from zero to a shipped MVP in about five months.
- 130+People, remote across Poland
- 44 daysFirst line of code to live, one consumer product
- 5.0Clutch rating, 11 reviews
This is for you if money or financial records move through your product
External events arrive unpredictably
Webhooks arrive twice, late or not at all, and nobody can tell what the app did with them.
Access has financial consequences
Every dollar has to be traceable per transaction.
Investigators or operators need evidence
Records from many sources that never describe the same event the same way, and an analyst who needs the answer in seconds.
What you get. Integrations with explicit financial behavior
Every payment path mapped
Failed charge, retry, refund, upgrade, downgrade, cancel and dispute, each mapped to what your app must do.
Reviewed transaction paths
Signature verification, idempotency keys, ordering and retries for webhooks, and permission checks on every sensitive action, failed paths included.
Reconciliation and audit support
A log of every webhook, charge and message, and a list of transactions already in the wrong state, built from your provider's records and your database. Settling past transactions is scoped and priced separately.
Tech stack. Money and chains, with controls
Smart contracts and payment rails built with idempotency, reconciliation and audit trails from day one.
Tech stack
- Solidity
- Ethereum
- Polygon
- Hardhat
- Foundry
- ethers.js
- The Graph
- Stripe
- Adyen
- Plaid
- Open Banking APIs
- Node.js
- PostgreSQL
- Kafka
- Vault
How we work
Trace the event beyond the request
We follow an operation through each system that can change its state. Design reviews cover delayed updates, partial failures and access boundaries before we implement the integration and its verification checks.
The team's main focus was quality, which is crucial in blockchain projects.
How it works. From financial event to reconciled state
Map systems and responsibilities
Map the providers, records and business rules that define a completed operation. Include failed charges, refunds, duplicated or delayed events and the resulting user access. Agree whether reconciliation of past transactions is part of the scope.
Define uncertain states
What the app shows when a payment is pending, a webhook is late or the provider is down.
Implement with security review
Signed webhooks, idempotency, permissions on who can move money, and tests for duplicate and delayed events.
Verify the operating workflow
Reconciliation and investigation steps checked with the people responsible for financial operations, against real records.
Proof, not promises
Security · Government
Financial-crime investigation software for Poland's authorities
FinTech · Government
AML-grade oversight for U.S. political ad spend, built from scratch
AI · FinTech
Taking over a crypto platform no one else could ship
Questions about financial and blockchain connections
- No. We work in your repository, your cloud and the tools your team already uses. If one of them gets in the way of the work, we tell you what and why, and you decide.
- With a 30-minute scoping call. We look at what you have and what you need, then propose a first step with its scope and price before any work starts.
- Yes. Before committing, we assess the requested integration, including the expertise and security review it needs.
- No. We build the technical controls your legal and compliance advisers specify, and document them. Compliance conclusions are theirs to sign.
- Yes. We work with the providers you already pay (Stripe, Paddle, Lithic, Plaid and others) and recommend a change only when the current one cannot do what the product needs.
- Every event gets a stable ID and an idempotency key, signatures are verified, and the handler checks what already happened before acting. We test the duplicate and late cases on purpose.
- Usually, from your provider's records and the app's logs. Where neither recorded it, we say so and add a log of every webhook, charge and message, so the next question has an answer.
- We list them from your provider's records and your database, and agree with you how each one is settled: refunded, fulfilled or corrected. Reconciling past transactions is a separate line in the scope, so you see it before you pay for it.
- A payments platform for US political campaigns, built on Lithic and Plaid; what slowed it down was the card provider's documentation contradicting itself, not regulation. Financial Trail for Matic: 1.5M+ transaction records from 350 raw files across 35 bank accounts, normalized in a single fraud case. Signal Mesh: a crypto market intelligence platform with an AI layer.
How we think about this, in our own words
Interactive briefs and articles by our team, picked for this service
How to Choose a Software Partner for a FinTech Product Without Increasing Regulatory and Delivery Risk
Five criteria and one question to help you evaluate a fintech software partner, including how they handle integration risk.
Read the articleBuild vs Buy in FinTech: When Custom Software Makes Business Sense
When custom software makes business sense in fintech, what AI changes and which risks vendors do not show you.
Read the articleAI Software Factory: a working product in six weeks
A consumer product with payments and subscriptions built in 44 days, and how its delivery loop worked.
Read the briefMap the transaction your systems need to agree on
Describe the financial workflow, external providers and records your team needs to reconcile.
Direct contact
Mike KacprowiczBook a callChief Growth Officer