Software engineering, built for institutions.
Arc Finlabs is a UK software and IT consultancy. We build custom web applications, internal tools, dashboards, and backend systems — with a specialist practice in payments and on-chain infrastructure for the clients who need it.
Arc Finlabs Limited does not provide regulated financial services and does not handle client funds.
Three areas of work. One bar for the work.
We engage where specialist payments engineering matters — and where the cost of a wrong decision compounds across scheme cycles, audit cycles, and customer trust.
Application engineering
Custom web applications and internal tools.
We build the operational software business clients run the work on — web applications, internal tools, admin dashboards, and the APIs that connect them to the rest of the stack.
Scope- Custom web applications on modern React / TypeScript stacks
- Internal tools and admin dashboards for operations teams
- API design, integration, and long-running maintenance
- Database architecture and query-layer engineering
- Cloud infrastructure support on AWS, GCP, and Vercel
- Ongoing technical maintenance and observability
Payments infrastructure
Card issuing, acquiring, and gateway integration.
A specialist practice for firms whose software touches payment rails. Scheme connectivity, authorisation paths, settlement, and the operational tooling around them — built to the standards auditors read.
Scope- Visa, Mastercard, and UnionPay scheme connectivity
- ISO 8583 and ISO 20022 message handling
- 3-D Secure 2 authentication flows
- Settlement, reconciliation, and dispute tooling
- PCI-DSS-aware architecture and scope reduction
- Integrations with principal processors and gateway operators
On-chain rails
Web3 systems that interoperate with the rest of the stack.
Non-custodial wallet architecture, cross-chain swap integration, and the bridge layers that let institutional software participate on-chain without taking custody of customer funds.
Scope- Non-custodial wallet architecture across EVM and beyond
- Cross-chain swap and bridge integrations
- MPC and hardware-backed signing patterns
- Key management architectures that survive audit
- On-chain settlement interoperating with card rails
- Card-to-chain top-ups and chain-to-card spend flows
We are engineers.
We chose where to build.
Arc Finlabs is a software engineering firm. Where a client's software touches money, we work card rails and on-chain rails with the same discipline: the same concern for correctness, the same tolerance for ambiguity (none), the same obligation to leave an auditable record.
Authorisation
Issuer approves a transaction in milliseconds.
Smart-contract invocation
Signed call, block-included, deterministically settled.
Settlement
Net funds move between bank accounts, batch by batch.
On-chain settlement
State change finalised; funds move without an intermediary.
Tokenisation
PAN replaced by a non-sensitive network token.
Token standards
ERC-20, ERC-721, ERC-1155 — assets as contracts.
Reconciliation
Match settlement records to transactions and fees.
State reconstruction
Replay chain state from logs to verify every write.
Dispute workflows
Chargebacks, representment, and scheme arbitration.
Dispute proofs
Signed off-chain evidence, on-chain commitment.
Five principles that hold for every engagement.
- Principle
Specificity.
We name the standard, the framework, the interface. Concrete nouns beat generic claims — in code, in architecture diagrams, and in conversation with your risk committee.
- Principle
Composability.
Small, testable pieces with clear contracts. Fewer frameworks, more primitives. Less surface area to explain to an auditor.
- Principle
Auditability.
If a write cannot be reconstructed from logs, it did not happen. Every critical path ends in a record the business can read, without a developer in the room.
- Principle
Restraint.
We ship what the work requires. No speculative features, no hypothetical abstractions, no framework tourism billed to the client.
- Principle
Verification before claims.
Type-checks, tests, dry-runs in staging against production-shape data. If it has not been proven, it does not go out.
Business clients that treat software as infrastructure.
BanksCard issuersCard acquirersPayment processorsPayment gatewaysNeobanksFintech operatorsAuditors
Financial institutions, fintech operators, and the auditors who review them — alongside business clients whose software runs their operations.
We take a small number of engagements at a time.
A short note by email is enough to open the conversation. Introduce yourself, the business you represent, and what you are trying to ship. An initial call typically follows within the week.
- Registered office
- 167-169 Great Portland Street, 5th Floor, London W1W 5PF
- Company number
- 17057409
- Jurisdiction
- England and Wales