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TheDaniel R Lessor

Vol. VIII · No. 404 ◆ Warszawa, Poland ◆ Backend Developer Edition ◆ Price: One Conversation
Exclusive Profile

Backend Developer Builds the Systems You Never Have to Think About

From Warszawa, Daniel R Lessor designs APIs, data pipelines and distributed services that stay quiet, fast and correct, even when traffic is not.

Daniel R Lessor
Pictured: Daniel R Lessor, backend developer, photographed shortly after a successful production deploy on a Friday afternoon. Staff Photographer

Daniel R Lessor is a backend developer who has spent the better part of a decade building the parts of software that users never see but always feel: the APIs that answer in milliseconds, the databases that never lose a row, and the background workers that quietly process millions of jobs a day.

Working mainly in Go, Python and Java, Lessor specialises in service design, relational data modelling and event-driven architecture. Colleagues describe an engineer who reads query plans for pleasure and treats observability as a first-class feature rather than an afterthought.

“Reliability is a feature. The best incident is the one that never makes the front page.”— D. R. Lessor

His work spans fintech, logistics and SaaS platforms, where he has led migrations from monoliths to well-bounded services, introduced contract-first API design with OpenAPI and gRPC, and cut cloud costs by right-sizing infrastructure on Kubernetes and AWS.

Beyond the code, Lessor is known for mentoring junior engineers, running blameless post-mortems, and writing the kind of documentation that turns a two-week onboarding into two days. He is currently open to new backend and platform engineering roles, remote or in Warszawa.

Continued in The Record, Page D1 ▸

Markets & SkillsSection B

The Skills Exchange — Closing Prices
ListingSectorYrsStrengthChg
GOLanguages64.1
PYTHONLanguages82.3
JAVA / KOTLINLanguages51.2
POSTGRESQLData83.7
REDISData61.9
KAFKAMessaging55.2
KUBERNETESInfra52.8
AWSCloud62.0
gRPC / RESTAPIs73.1
Market Analysis

Steady Gains Across the Stack as Fundamentals Stay Strong

Analysts point to a diversified portfolio anchored in typed, compiled languages and battle-tested relational databases, with growing positions in streaming and cloud-native infrastructure.

Also trading:

DockerTerraformRabbitMQElasticsearchMongoDBGraphQLOpenAPIPrometheusGrafanaOpenTelemetryGitHub ActionsLinuxDjangoFastAPISpring BootDDDTDDCQRS

Dispatches from the Server RoomSection C

Fintech

Ledger Rebuilt on Event Sourcing; Not a Single Cent Lost

API Event Log Balances Audit

Fig. 1 — Commands become immutable events; read models are projected.

A double-entry ledger handling 2M transactions daily was moved from mutable rows to an append-only event store in PostgreSQL, with idempotent command handlers and replayable projections.

Go · PostgreSQL · Kafka · CQRS

Logistics

Routing API Cuts Response Times by 62%

A sluggish shipment-routing service was profiled end to end. Rewritten SQL, covering indexes and a Redis read-through cache took p99 latency from 840 ms to 320 ms under peak load.

“The fix was in the query plan all along.”

Python · FastAPI · Redis · PostGIS

Platform

Unified gRPC Gateway Tames Thirty Microservices

A contract-first gateway with protobuf schemas, mTLS, rate limiting and request tracing replaced a tangle of ad-hoc REST clients, giving every team the same auth, retries and metrics out of the box.

Go · gRPC · Envoy · OpenTelemetry

SaaS

Monolith Carefully Split, Customers Notice Nothing

Using the strangler-fig pattern, billing and notifications were carved out of a ten-year-old Django monolith into independent services, with feature flags and shadow traffic validating every step.

Python · Django · RabbitMQ · Kubernetes

Data

Streaming Pipeline Delivers Analytics in Seconds, Not Hours

Nightly batch jobs gave way to a Kafka-based change-data-capture pipeline feeding ClickHouse, putting near-real-time dashboards in front of operations staff.

Kotlin · Kafka · Debezium · ClickHouse

Open Source

Small Library, Big Relief: Idempotency Made Simple

A lightweight Go middleware for idempotency keys and safe retries, backed by Redis or PostgreSQL, now used in several production payment flows.

Go · Redis · Middleware · MIT License

The RecordSection D · Career

2022Present

Senior Backend Developer

Fintech payments platform · Warszawa / Remote

  • Lead engineer on the core ledger and payouts services in Go.
  • Designed an event-sourced architecture processing 2M+ transactions a day.
  • Introduced SLOs, tracing and on-call runbooks; cut incident count by 45%.
  • Mentors five engineers and chairs the API design review.
20192022

Backend Engineer

Logistics & delivery scale-up

  • Built routing, tracking and partner-integration APIs in Python and FastAPI.
  • Moved services to Kubernetes on AWS, reducing hosting costs by 30%.
  • Designed the Kafka event backbone shared by twelve teams.
20172019

Junior Software Developer

B2B SaaS software house

  • Developed REST endpoints and background jobs for a Django/PostgreSQL product.
  • Wrote the team’s first integration test suite and CI pipeline.
  • B.Sc. in Computer Science; certified AWS Solutions Architect – Associate.

Letters & ClassifiedsSection E

Letter from the Editor

On Building Things That Last

Good backend work is rarely glamorous. It is careful schema design, thoughtful error handling, sensible timeouts and tests that fail for the right reasons. It is choosing the simpler architecture when the simpler one will do.

I enjoy that kind of work, and I enjoy doing it with people who care about it too. If your team needs someone to untangle a slow service, design an API that will age well, or make the pager go quiet, I would be glad to hear from you.

The classifieds to the right list every way to reach this desk. Replies are typically sent within one business day.

— Daniel R Lessor

Classifieds

Contact the desk directly · Rates: free of charge

Position Wanted

BACKEND DEVELOPER AVAILABLE

Experienced engineer seeks backend, API or platform role. Go, Python, PostgreSQL, Kafka, Kubernetes. Remote or Warszawa. Serious enquiries welcome.

Name

Daniel R Lessor First name: Daniel R
Surname: Lessor

Telephone

+1 346 446 9459 Calls & messages accepted.

Correspondence

ref07937@gmail.com Reply within one day.

Postal Address

Przepiorki 1, Warszawa - 02407, Poland Daniel R Lessor · Przepiorki 1 · Warszawa - 02407 · Poland
Place an Enquiry