Neibr: the backend of a B2B API for parcel carriers
B2B API for parcel carriers. When a delivery fails, the parcel goes to a neighbour within 200 m instead of going back to the depot.
It was one of the winning projects of the Santander X Spain Awards 2026 (UVic).
My part
Besides the backend, I set up the deployment and the website, and took part in sales and the company's social media.
How a neighbour was assigned
Assignment prefilters by bounding box in SQL, then computes the exact distance with Haversine.
Go (Fiber), PostgreSQL and Redis.
- 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.
Security and integrity
Each carrier had its own keys, a repeated request didn't create duplicates and notifications were signed. Operations went into an audit record that couldn't be changed.
Multi-tenant API keys, idempotent writes, HMAC-signed webhooks and an immutable audit ledger.
Neibr: API stress test
- requests in 50 minutes
- 2.9 M
- requests per second
- ~968
- 95 out of 100 responses (p95)
- < 100 ms
- server errors (5xx)
- 0
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).
// POST /api/v1/b2b/shipments// X-API-Key: pk_live_…{ "geo_lat": 41.6079, "geo_lng": 2.2874, "pickup_window_hours": 48, "expires_at": "2026-12-31T23:59:59Z"} → 201 Created{ "tracking_number": "CARRIER-000001-01042026", "status": "ASSIGNED", "seed_node": "node_3B", "distance_m": 47}Why we shut Neibr down
Talking to a large carrier showed us problems in the model that code wasn't going to fix, so we shut it down in 2026, before launch.
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