Stephen O'Sullivan

Software

Availeth · Navillus Contracting · Linesight

I build construction companies their software, and they own it.

I founded Availeth, LLC in July 2026. We build contractors the software they currently rent, inside their own cloud, against the systems of record they already run. The client owns the code and the tenancy at the end of it. There is no per-seat licence.

I also run the AI and software effort at Navillus Contracting, a New York general contractor of about 150 staff and 103 union field employees. In nine weeks there I delivered 26 production systems across payroll, timekeeping, project management, meetings, HR and IT. They are in daily use, and they run for roughly the cost of a single mid-market subscription.

Twenty six systems, nine weeks

Live software, in daily use, at a New York general contractor.

I wrote the back ends, the payroll engine and every integration. No consultants were hired and no engineers were added.

Payroll and timekeepingSix systems

Jobber

Reads handwritten field timesheets, applies union pay rules and posts certified payroll into Sage 300 CRE.

HH2 and Sage integration

Queries Sage 300 CRE in plain English and moves hours and payroll in and out automatically.

Clock-in and Timeclock

A live board of who is on site, and missing punches resolved before each weekly close.

NewHoursApp

Mobile clock-in for field crews, shipped as a real app on iOS and Android.

Cadence

Mobile vacation and leave approvals for managers, with reminders.

Payroll platform

Weekly union and certified payroll calculation.

Construction and project managementSix systems

Procore automation

Automates RFIs, submittals, daily logs and uploads. Every write passes a confirm step.

Project management

Unifies Sage cost codes, ExakTime labour and Procore into one project view.

Takeoff OS

Quantity takeoff for estimators, built in an afternoon because the trade needed it.

Construction tools

Kahua integration, plus field photo and pile-data mapping.

Job Roster

A live roster of which project manager, superintendent or APM is on which job.

Site logistics

Tracks deliveries, dockets and gate sign-ins for a general contractor.

Meetings, HR and peopleFive systems

Minute Machine

Joins Teams meetings on its own, writes formal minutes and files them to attendees only.

Leave Tracker

Vacation and holiday requests, balances and approvals.

Nav Reminders

Scheduled recurring reminder mail for the payroll and project management teams.

Onboarding

An onboarding site and a project manager playbook for working with AI.

Hiring

Resume ranking and the graduate hiring scheme it feeds.

Dashboards, IT and governanceSeven systems

Estate ops and audits

Automated code review, security review and access audits across every system in the estate.

IT infrastructure

Microsoft 365 backup and migration, a secure on-premise network bridge, DNS and secrets.

Command Centre

A live executive dashboard of company performance, served on the company domain.

Payroll intelligence corpus

A searchable record of who works where, and of pay rules by trade.

AI Usage Stats

Company-wide dashboard of AI adoption, usage and return.

Video Hub

Internal video library and a reusable brand and design system.

Microsoft 365 tooling

Tenant administration, diagnostics and identity linking.

The integration layer took the longest and matters most. I have written MCP servers for Sage 300 CRE, Procore and Microsoft Graph, so that a model can read and write the systems of record directly. Every write passes a confirm step. Nothing posts to a ledger without a person saying yes.

On my own

Two products built outside any employer.

Aerota

Live since January 2026

Staff scheduling for small businesses, built to hold the awkwardly specific constraints a real roster carries. Nothing to a deployed production MVP in one month, working alone. React and Vite on Vercel, Node and Express on Railway, PostgreSQL with row-level security, Stripe billing, WhatsApp through Twilio, and the Anthropic API for reading constraints written in plain language. Roughly 79,000 lines, 27 migrations, and an end-to-end test suite. The API has been serving for six months.

Control Tower

2026

Project controls in one application: calendar, foundation, cost, schedule, risk and change. React, Express and PostgreSQL, roughly 69,000 lines. The first working version took about a day.

Elsewhere

Before Navillus, at a firm with no connection to it.

At Linesight, a construction consultancy in Frankfurt, I proposed, built and demonstrated a set of custom applications on my own initiative: a Python scheduling application covering over 100 meetings a month in place of a manual Excel process, n8n and AI automation workflows for cost reporting and change management, and cashflow forecasting models extended past linear and manual input to Gaussian, logistic and exponential spend scenarios. Linesight had not adopted them by the time I left, which is a fair outcome roughly a month on from a first formal proposal inside an institution that size.

Stack

How it is built.

Everything runs in the client’s own cloud, which is almost always Azure, because contractors are already on Microsoft 365. Azure Container Apps, Bicep for the landing zone, Entra ID for sign-on. Back ends in Python and FastAPI, with .NET where a client already has it. Data in SQL Server, which is what Sage 300 CRE runs on. Front ends in React and Vite. Anything the field touches has to be a real phone app, so those are built with Capacitor, or in Swift and SwiftUI natively where the app needs the device itself.

The software is written with Claude Code. I use it as the means of building rather than as an assistant, and I would rather say so plainly than imply otherwise.

Construction

Seven summers on site · engineering on paper and in the field

I worked in the trade before I wrote software for it.

Seven summers with a New York general contractor. I started at 17 as a crane rigger, jumping luffing cranes on high-rise sites with a team of eight, then worked as a labourer, then as an assistant project manager, and later in the union as a Local 1556 dockbuilder. That is where I learned what a shop steward will accept as a sign-in sheet, and why prevailing wage makes off-the-shelf payroll useless in this city.

Roles

Linesight, Frankfurt

2025 to 2026

Project controls graduate on cost reporting, change management and forecasting for large developments.

Geotechnical Laboratory, Trinity College Dublin

2024

Research assistant. Principal author of a conference paper on pile ageing in sands. Designed, wired and programmed digital measurement systems to retrofit onto analogue laboratory equipment, and wrote the Python used in the analysis.

Navillus Contracting, New York

2017 to 2023

Assistant project manager and Local 1556 dockbuilder. Helped direct a team of over 70 employees and five subcontractors on a $60 million jobsite, coordinated drawings and submittals, ran site procurement, and monitored safety qualifications for over 100 workers. In the field, installed a fibreglass fender system around a cross-channel rail bridge with a team of eight and a crawler crane, which involved gas torch operations, steel working, machining and welding.

Engineering Design Consultants, Dublin

2021

Mechanical and electrical design intern. Designed and specified HVAC systems for large developments from self-performed calculations, in accordance with building regulations.

Engineering

Integrated Bachelor’s and Master’s in Mechanical and Manufacturing Engineering, BAI and MAI, Trinity College Dublin2019 to 2024
Master’s thesis: An Investigation into the Mechanisms of Pile Ageing. Distinction, 79%2024
S. O’Sullivan, S. S. Kasyap, D. Igoe, ‘Understanding Pile Ageing Mechanisms in Sands through Shear Box Testing’, CERI2024, Galway, pp. 238 to 2422024
Kinsella Scholar, Eric and Barbara Kinsella Foundation2020 to 2024

At 19, all outreach for one niche trade, geomembrane installation, returned bids which seemed exorbitantly high. Given Navillus’ own expertise and labourers, I thought we could perform it ourselves, and on researching further I found every barrier was regulatory and licencing-related. I proposed, and personally led, a project for the company to enter the trade itself. It bought its own liner and welding plant that September and installed the membrane with its own labourers rather than letting the scope out.

Reading & Writing

Irish history · debating · television research

History, mostly Irish, and the argument about it.

I write on Irish history and I have researched for television. Five years of competitive debating taught me most of what I know about making an argument hold, and about being wrong in front of a room, which is the more useful of the two.

Written and made

Fiosrach, a Substack on Irish historyOngoing
Researcher, A Day in May, a fifty minute documentary2025
Bramcast, founded, produced and hosted. Seventeen episodes with academics, politicians and journalists2023 to 2024
‘Communist Amnesia: The Crimes of the Early Bolshevik State’, a paper delivered to The Bram Stoker Club2024

Research

The Bone Service, a book in progress, written with Patrick BolandCurrent
11 Parnell Square, Dublin. Building history from the Freeman’s Journal, the British military archives and the excavation record, covering the National Club that occupied it2023

Societies and debating

Chairman, The Bram Stoker Club, Trinity College Dublin. Ran a five person committee and twenty four weekly paper readings2023 to 2024
Grand Finalist, The Irish Times Debate, the national championship2024
Winning team, Trinity College Dublin versus Yale Debate2023
Member of the Year, The University Philosophical Society2022 to 2023
Irish Language Residency Scholarship, Trinity College Dublin2019 to 2020