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Backend · Systems · Full-Stack

Don Shammah

I design backend systems that stay correct under failure. As the solo architect of Build Market, I built an event-driven construction and real estate platform for East Africa — statutory compliance state machines, milestone escrow, and capability-based security included.

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  • Node.js 24
  • TypeScript
  • NATS JetStream
  • BullMQ
  • PostgreSQL
  • Prisma
  • Next.js 16
  • Cloudflare
  • M-Pesa Daraja
4Apps in the monorepo
9Statutory boards covered
26Ratified ADRs
47Counties covered
01

Selected work

Flagship system buildmarket.app Turborepo monorepo

An event-driven marketplace, compliance engine, and project-coordination platform for Kenya's construction industry. It addresses offline trust gaps, uncertified contractors, and counterfeit materials through milestone-based escrow and statutory verification pipelines.

System architecture
Workspace topology

apps/client Edge BFF

Edge-optimized portal for homeowners, professionals, and merchants. Cloudflare Workers via OpenNext.

apps/admin Control Plane

Capability-based RBAC, safeAction adapters, tiered step-up freshness guards, immutable audit log.

apps/verification-ops Regulator Queue

Credential review against NCA, EBK, BORAQS, EARB, EPRA, VRB, ISK, NEMA, and KEBS.

apps/workers Container Daemon

Node.js 24 Alpine daemon on Render with HTTP liveness probes, BullMQ, and NATS JetStream subscribers.

System surfaces & cryptographic execution evidence
Use ← → keys or click to inspect Swipe or tap tabs · Tap to expand

Statutory verification

State machines verifying individual and firm credentials against nine statutory boards, with an operator fallback when registers are down.

FinTech & escrow

Daraja 2.0 STK push, B2C disbursements, bank escrow trust model, and KRA eTIMS invoice reconciliation.

Lifecycle & BoQ engine

Digital Bill of Quantities, staged milestones, inspection audits, and change-order controls.

Materials commerce

Multi-vendor directory across 21 categories with county-level fulfillment in all 47 counties.

Distributed messaging

JetStream streaming, consumer-group load balancing, BullMQ worker pools, and DLQs.

Edge & cloud infra

Cloudflare edge compute paired with containerized Render workers and Redis pipelines.

Frontend & edge
Next.js 16React 19TypeScriptCloudflare WorkersR2Tailwind 4Radix UITanStack Query
Backend & infra
TurborepoRenderNode.js 24NATS JetStreamBullMQDockerSharpBlurhash
Data, payments & security
PostgreSQLPrisma 7RedisM-Pesa DarajaClerkOpenTelemetryDatadogPino
2-minute executive summary + full deep diveRead the Build Market architectural case study
Read case study

Engineering decisions & essays

Acknowledge only after commit

Consumers call ack() only once the database transaction commits. A crash in between triggers redelivery, and idempotent upserts make the replay harmless, so nothing is lost or applied twice.

Read essay → Every handler must be idempotent.

Degrade, never block

When a regulator portal is down, a circuit breaker opens and the license moves to pending. A NATS retry stream keeps trying for 24 hours, with a human review queue as the last resort.

Read essay → Multi-stage regulator fallback.

Authority lives in the database

Admin capabilities resolve from a database profile on every mutation, never from token claims. Critical actions also require fresh step-up re-authentication within strict tiered freshness windows.

Read ADR-ADMIN-001 → One extra DB read per admin mutation.

Non-custodial escrow

Milestone funds sit in a licensed bank or PSP trust account, tracked by an internal claims ledger, with idempotent M-Pesa disbursements. The platform never commingles client money.

Read essay → Non-custodial M-Pesa Daraja 2.0 waterfall.
02

Backend projects

01

Event Streaming Platform

NATS-backed pub/sub with schema validation, consumer groups, dead-letter queues, and a dashboard for topic inspection and event replay.

NATSTypeScriptPostgreSQLDocker
02

Distributed Task Queue

Fault-tolerant job scheduler with at-least-once delivery, BullMQ worker pools, and a pluggable backend interface.

TypeScriptBullMQRedisNode.js
03

Type-Safe API Gateway

Reverse proxy with tRPC routing, JWT auth, per-IP rate limiting via Upstash, and distributed tracing.

TypeScripttRPCRedisAWS
04

AI Workflow Engine

LangChain orchestration for multi-step LLM pipelines with tool calling, memory management, and streaming via the Vercel AI SDK.

LangChainVercel AI SDKPostgreSQLNode.js
05

Resilience Library

Fault-tolerance primitives for Node.js: circuit breakers, exponential backoff with jitter, bulkheads, and timeout wrappers.

TypeScriptNode.jsSupabase
06

Observability Stack

Telemetry pipeline with structured NDJSON logging, correlation IDs, distributed tracing, and Grafana dashboards for SLOs.

OpenTelemetryGrafanaAWSNode.js
03

Toolkit

Backend

TypeScriptNode.jstRPCPostgreSQLPrismaRedis

Distributed systems

NATS JetStreamBullMQEvent-driven designState machinesIdempotencyDLQs

Platform & delivery

Next.jsCloudflare WorkersDockerTurborepoOpenTelemetryAWS
04

Experience

Solo Software Engineer & Founder

Build Market · Nairobi (Remote)

Designed and built a construction and real estate marketplace for East Africa as a solo engineer. Turborepo monorepo with Next.js and tRPC, a NATS event bus for decoupled messaging, BullMQ/Redis for background jobs, Clerk for session auth, and M-Pesa APIs for local payments.

05

About

I'm a software engineer in my third year of building, focused on backend systems, clean architecture, and distributed infrastructure. I care about systems that are correct by design — not just fast, but sound under failure. Building Build Market alone taught me monorepo orchestration, event buses, and custom capability-based authorization the hard way.

Let's build something dependable.

Open to backend, systems, and full-stack engineering roles.

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