I keep busy systems fast, cheap and up.
I'm Mo. I spent the last three years building Harbor (YC W19), a community platform for game studios with over 10 million registered users. I owned features end to end, from the Next.js dashboard down to the .NET and Node services and the database under them.
Available now. Harbor's team shut down in August, so I'm looking for my next one. Dubai, and happy with on-site, hybrid or remote.
A few fixesHarbor, at 10M+ users.
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1B+ rowslocked across 270 tables
A cascading MySQL delete locked over a billion rows and took the platform down. I led the diagnosis and the recovery, and brought service back for every user.
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100% → <50%chat service CPU
Our chat service was pinned at full CPU. I reworked the slow queries, cached account data and message history, and lazy-loaded older messages. It settled under half, with messages landing in about 100 ms.
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−98%YouTube API costs
I split YouTube data collection into two phases, so we only paid to fully fetch channels with two or more subscribers in the community.
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−33%AWS bill
One API token was hitting us 1,200 times a second, day and night, for two and a half months, and the total still looked normal. I found it by reading the bill service by service, put in a rate limit nothing can get around, and cleared out idle services and oversized servers on the way. The bill came down by about a third.
Work4+ years, mostly remote for US teams.
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Harbor by Windwalk, YC W19
Sep 2023 – Aug 2026Software engineer, full-stack
A no-code community platform used by about 100 game studios, NZXT and Stumble Guys among them. I built our chat on WebSockets, then moved it onto the Discord Social SDK with a small C++ service that relays events to .NET over NATS. I also built a 33-filter segmentation engine so marketing could target users without us, connected 10+ platforms from Twitch to App Store Connect, and set up an LLM sentiment pipeline that reads 50,000+ community messages a day.
Next.js · React · C#/.NET · Node.js · MySQL · Redis · AWS · NATS · WebSockets
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Libertas
May – Sep 2023Full-stack engineer
Premium Discord bots. I built memberships, subscription billing and feature gating in Node.js and Prisma, plus the self-service dashboard in React and Laravel. Subscription revenue went up 25%.
Node.js · Prisma · MySQL · React · Laravel
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ShopX
Oct 2022 – May 2023Full-stack engineer, Cairo
A multi-vendor marketplace. I built the catalog, orders and vendor payouts, ran it all on AWS, and mentored two interns.
NestJS · PostgreSQL · Prisma · Jest · AWS ECS and RDS
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Jego at Abovav Inc.
Sep 2021 – May 2023Software engineer, contract
Three production mobile apps for Abovav's clients, with scope and delivery agreed with each client directly. One was Jego, where EV drivers find and book nearby chargers on a map.
Flutter · Firebase · Node.js · Stripe
How I work
Measure first. I don't optimise until I know where the time or money actually goes, and then I fix the cause instead of hiding it behind a cache.
Read past the total. The worst problems I've found looked fine in the summary and obvious one level down.
Build it so nobody has to ask. I'd rather give marketing a segmentation engine they can run on their own than run their queries for them.
Lately
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A weather MCP server
2026A small Model Context Protocol server, in Python, that lets AI clients pull forecasts from Open-Meteo.
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Retrieval-augmented generation, DeepLearning.AI
2026Compared semantic, BM25 and hybrid search in Weaviate, then built and evaluated a RAG chatbot on open models.
Education
The German University in Cairo
Grade A · 90.6/100BSc Computer Science and Engineering
My thesis identified people from their ECG signals with machine learning, at 97% accuracy. I also took first place in the ITWorx Coding Competition.
Hiring, or just want to talk shop?
hi@mohoss.net