Naplen

Fintech software development for systems where a wrong state costs real money

In software that moves money, the hard part is knowing what actually happened, and speed comes second. A trade that looks failed but landed, or a price that is hours old behind a green dashboard, costs the same as a crash. I build financial systems that keep an honest record of their own state, and the work reaches your repositories as reviewed pull requests.

Areas of work

After an unclear response, send the same transaction again

When a broadcast returns an ambiguous answer, the tempting fix is to sign a new transaction and try again. That is how a system ends up with two trades where it meant one. I save the signed transaction before it is broadcast, and after an unclear response I rebroadcast that same signed payload instead of signing a second one.

A success is recorded from its receipt, matched on the transaction hash, and not from the last response the system happened to see. In one trading system a position was marked failed while its replacement had already succeeded, which is the state this approach removes.

A dashboard can show a price that is hours old

A number on a screen looks current whether it is or not. If the job that refreshes a price has stopped, the dashboard keeps showing the last value it had, and nothing on the page says so.

I put the time a number was captured next to the number, and I alert on a job that stops, so stale data is visible to the person reading it and to the on-call engineer.

A test of a trading system has to be able to fail it

A backtest that cannot say no only confirms what you hoped. I keep data back that the system was never tuned on, write the rule for what counts as a success before the run starts, and check that the simulator behaves like the live system it stands in for.

You keep your strategy. I build the checks around it, and I do not publish strategy results, rules or thresholds.

Reviewed changes arrive in your repositories

An engagement starts with a workflow review. I look at how work moves through your team from ticket to production and what my software factory can take on, and you leave with a plan either way.

After that the factory does the volume, I review what it produces, and you set the priorities without a calendar full of meetings.

Start with a workflow review of the system where a wrong state would cost you the most.

Capabilities

Trading infrastructure

  • Trading platform architecture
  • Market data ingestion and processing
  • Order routing and execution infrastructure
  • Exchange connectivity and API integrations

Low-latency and high-throughput systems

  • Performance-sensitive backends
  • Low-latency networking
  • Concurrent and asynchronous systems
  • High-throughput data processing

Blockchain infrastructure

  • Solana infrastructure and streaming
  • Ethereum infrastructure
  • Wallet and custody infrastructure
  • On-chain monitoring and indexing

Smart contracts and financial applications

  • Smart contract development and integration
  • DeFi infrastructure
  • Payment infrastructure and financial APIs
  • Non-custodial financial applications

Stack

  • Rust
  • Go
  • TypeScript
  • Python
  • Postgres
  • Redis
  • Kafka
  • gRPC
  • Kubernetes
  • Terraform
  • Solana
  • Ethereum

Related services

[email protected]