Backend & API Engineering
The backend is where the decisions that are hardest to reverse get made. A data model that does not fit the domain, or an API that leaks its internals, becomes the constraint every future feature has to work around. We build that layer to survive the features nobody has asked for yet, and to stay correct when two things happen at once.
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API design and versioning
Interfaces designed around what consumers need rather than what the database happens to contain. Versioned properly, documented, and changed without breaking whatever is already calling them.
Data modelling and migrations
Schemas that reflect the real domain, including the awkward parts. Migrations that are reversible, tested against production-shaped data, and run without downtime.
Service and queue architecture
Splitting work along boundaries that reflect how the system actually behaves. Queues, retries, idempotency and dead letter handling, so a failure is recovered from rather than lost.
Correctness under concurrency
The failures that matter are the quiet ones: a double charge, a lost update, a balance that drifts. We design for concurrent access explicitly rather than hoping the load stays low.
How we work
Model the domain before the endpoints. The API is a consequence of the data model, not the other way round. We get the model right first.
Define the contract. Interfaces, error shapes and versioning agreed and written down before implementation, so consumers can build against them in parallel.
Build with the failure cases first. Retries, partial failures and concurrent writes are designed in at the start rather than patched in after the first incident.
Verify against a measurement. Correctness under concurrent load is tested, not assumed. If a claim about behaviour cannot be measured, it is not a claim we make.
Document what the next engineer needs. The contract, the invariants and the reasons behind the awkward decisions.
Our tech stack
- Runtime
- Node.js, TypeScript, Java, Akka
- Data
- MongoDB, PostgreSQL, Redis, schema migrations and versioned data models
- Interfaces
- REST, WebSockets, GraphQL, webhook delivery with retry and signing, OpenAPI specification
- Reliability
- queue-backed processing, idempotency keys, structured error handling, dead letter queues
Why work with us
We design for the failure, not the happy path.
Retries, partial writes and race conditions are considered at design time, because they are the expensive class of bug.
Correctness first.
A slow page is annoying. A billing error is a lost customer and a refund.
The contract survives us.
Documented interfaces and stated invariants, so the next person to touch it does not have to reverse engineer your intent.