Contact

Open to new freelance projects

Freelance backend developer

Valerio Farrotti, passionate about open source and Bitcoin.

Building backend systems professionally since 2018: APIs, data models and the pipelines that ship them. CI/CD automation and simplicity.

Tell me about your projectSee my work →

How I can help

  1. Build a new backend
  2. Scale or rework an existing system
  3. Set up delivery and operations

Build a new backend

From blank repo to production

APIs, data model and auth designed together, with tests from day one.

  • API design (REST, gRPC, OpenAPI)
  • Modular, layered architecture
  • Data models and database-backed workflows
  • Authentication and secrets management (OAuth/JWT, token verification, Vault)

Where I did this

  1. 01 · Used daily by hundreds of end users

    A regulated crypto fintech

    • Python
    • Go
    • REST / OpenAPI
    • gRPC
    • PostgreSQL
    • Redis
    • Kafka
    • AWS
    • Serverless Framework
    • Docker
    • Kubernetes
    • ArgoCD / GitOps
    • Nix
    • Jenkins
    • Prometheus / Grafana
    • Vault

    Designed and built the subscription and recurring-billing service: plans, renewals, promotions and payment events.

    • A compliant crypto-withdrawal flow with travel-rule validation
    • A Kubernetes/GitOps delivery platform (multi-environment, service mesh, canary releases) for new Go services

Scale or rework an existing system

Without stopping it

Take a service that has outgrown itself and make it run as many instances.

  • Fault-tolerant, horizontally scalable services
  • Event-driven and async processing (Kafka, Redis)

Where I did this

  1. 02 · Team work

    An industrial-automation Client

    • Java & Spring Boot
    • Oracle
    • RabbitMQ
    • TypeScript & React
    • Docker
    • Nix

    Rewrote the job scheduler to run as multiple stateless instances: a database row-lock state machine and a lease-based deadline sweeper. Two instances run today and it scales on command.

    • Nested parallel groups, shipped end to end across engine, API and editor UI

Set up delivery and operations

Ship often, sleep well

Pipelines, clusters and alerts, so releases are boring.

  • Automated testing, build and deployment pipelines
  • Kubernetes, GitOps and Serverless Framework
  • Metrics and alerting (Prometheus/Grafana)

Where I did this

Kubernetes/GitOps delivery platform at a regulated crypto fintech: part of the a regulated crypto fintech engagement above.

Remote, based in Italy (CET) · English & Italian · Fixed-scope projects or ongoing work, direct or through your agency.
I work with coding agents, and I design, review and own everything they write.

More work

  • Team work over 16 months

    A production-line inspection Client

    Real-time computer-vision inspection of a live production line: a multi-process pipeline, backend error checking and CAD-based flaw detection, in production.

    • Automated per-session production reports from time-series data (sole author, in production)
    • Python
    • Computer vision (OpenCV)
    • InfluxDB
    • Node.js
    • Vue
    • C#/.NET
    • Docker

  • Sole engineer

    A tax-assistance product

    In delivery

    Building the product end to end: a Rust/Axum API and a Flutter app.

    • Secure sign-in: local Google/Facebook token verification, rotating sessions, one-time tokens
    • A domain model for the Italian 730 tax-return lifecycle
    • Rust (Axum, SQLx)
    • Flutter
    • PostgreSQL
    • OAuth/JWT
    • OpenAPI
    • Docker
    • Nix

  • Open source

    OHomeMy

    A Home Assistant integration for building dashboards graphically, released through HACS and in active development.

    • Python
    • TypeScript & React
    • Home Assistant (HACS)

    View the repository ↗

  • Open source · 61★ · 7 forks

    Conda-autoactivate-env

    Adds auto-activation of Conda environments on Unix shells. Outside contributions maintained since 2021.

    • Shell (bash, zsh, Nushell)

    View the repository ↗

What I work with

Everything above is used in at least one Case study.

Languages

  • Python
  • Go
  • Rust

APIs & auth

  • REST
  • gRPC
  • OpenAPI
  • OAuth/JWT
  • Vault

Data & messaging

  • PostgreSQL
  • Redis
  • Kafka
  • RabbitMQ

Cloud & delivery

  • AWS (Lambda, API Gateway, S3)
  • Serverless Framework
  • Docker
  • Kubernetes (Helm, Kustomize)
  • ArgoCD / GitOps
  • Nix
  • Jenkins & CI pipelines
  • Prometheus / Grafana

Also shipped with

TypeScript & React · Flutter · Java & Spring Boot · Node.js · Computer vision (OpenCV) · InfluxDB · Shell (bash, zsh, Nushell)

Hands-on with · from personal projects and experiments

Django · Zig · OpenTelemetry · ClickHouse

Open-source contributions:Bitcoin Core RPC client for walle (Zig Bitcoin wallet)transaction broadcasting for walledocs for devbox

Tell me what you're building

Open to new freelance projects. A few lines about the problem are enough. I reply within two working days.

valerio@farrotti.com