Backend and API developer in Granollers, near Barcelona
I design and build APIs, microservices and integrations in Go, Java and Node. These are the systems I can show.
Neibr: a B2B API in Go
When a delivery fails, the parcel goes to a neighbour within 200 m instead of going back to the depot.
Go (Fiber), PostgreSQL and Redis. Assignment prefilters by bounding box in SQL, then computes the exact distance with Haversine.
Multi-tenant API keys, idempotent writes, HMAC-signed webhooks and an immutable audit ledger.
About 2.9 million requests in 50 minutes, some 968 per second. Of those, 95% were answered in under 100 ms (p95) and none returned a server error (5xx).
How I built the Neibr backend- A delivery fails at this point.
- An SQL prefilter keeps the neighbours inside a square (bounding box).
- The 200 m circle leaves out the ones too far away.
- The nearest one is highlighted, with its exact distance worked out with Haversine.
VMV Cosmetic Group: 20 microservices and AS/400 integration
I was the lead web developer at an international cosmetics company. I looked after all of its web work: domains, in-house WordPress plugins and microservices in Go, Java and Node.
Go WAF
With IP reputation.
Java 21 bridge to the ERP
Java 21 / Spring Boot 3 services that expose the AS/400 ERP as REST, behind an anti-corruption layer.
Corporate magazine
Collaborative editing, per-issue versions and real-time preview.
Public demo of the magazineAI gateway
A single entry point to language models, with an OpenAI-compatible API.
Document signing with biometrics
A Next.js platform that tracks each document from creation to archive.
Async PDF engine
Generates PDFs in the background and shows their status in real time.
WhatsApp Business notifications
Notifications for the regional offices, in Go.
Backups
They hand the heavy work to child processes, outside PHP's memory limit.
Payments on vending machines
I help integrate WiPay with vending machines at Automated Transactions. The cashless payment connects to the machine over MDB. The actual work: translating payment payloads to hexadecimal over a serial bus at 9600 baud.
How I work
The API and the data first
Before writing business logic, I design the API contract and the database schema. Both are documented, the API in versioned OpenAPI.
I measure before changing things
Structured logs and metrics from day one, and I read the logs before touching anything. In the Neibr stress test, p95 stayed under 100 ms at about 968 requests per second.
I plan for failure
Timeouts, retries and rate limits from the start, and I validate external data before processing it. In Neibr, idempotent writes and HMAC-signed webhooks.
Docs next to the code
Short ADRs for the decisions that matter and READMEs you can actually run. Digital DesAny projects are delivered with full technical documentation.
Technologies
I use Go and Fiber, Java 21 and Spring Boot 3, Next.js, React and TypeScript, WordPress and PHP, PostgreSQL, Redis and Docker.
Custom software for your business: the service page at digitaldesany.com
Tell me about your project
Oriol Tamborero and I run client projects through Digital DesAny, in Granollers. Tell us what you need and by when, on WhatsApp or by email.
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For anything else
Write to me: contact@alexasto.com