Commercial ConstructionNashville, TN2025–present
A credibility-first front door, and an AP pipeline that runs itself.
A decade-old Nashville commercial builder had a web presence that undersold the firm, plus an accounts-payable process that ran on manual invoice entry across hundreds of active projects.

“He has proven to be an exceptional partner who not only delivers what he promises, but he also consistently finds ways to deliver more than we ever thought possible.”
What changed
Accounts payable
Before: Manual invoice entry
Inbox → QuickBooks
Vendor invoices arrive by email or upload, get parsed by Claude vision, pass a PM review, and post to QuickBooks Online as Bills with the PDF and project attached.
Sales presence
Before: Underbuilt web presence
Credibility-first site
The site opens on the firm’s real record: established 2015, 350+ projects completed, and an unlimited Tennessee contractor license.
Build stack
React 19 + FastAPI
The same modern stack RelentNet runs in-house, self-hosted on Coolify with Cloudflare R2 storage.
Challenge
Cambridge Building Group does high-trust commercial work, but the previous web presence did not communicate that. Prospects landed on a site that under-represented the company and gave sales conversations nothing to lean on.
In commercial construction, the website is not a brochure. It is a stage in the buying process. A weak stage costs the firm conversations it should be having.
The diagnostic showed the real problem was sales friction, not visual design. Serious prospects needed to understand capability, credibility, and positioning within a few seconds of arriving on the site.
Typography, project imagery, and contact paths all needed to serve that one job.

Solution
The engagement grew into two pieces of software. The first is the public marketing site, built on React 19, TanStack Router, Tailwind 4, and Motion, with deliberate visual hierarchy and conversion-focused inquiry paths, so a prospect at the top of the funnel and one ready to talk both find the right next step.


The second is an internal AP portal. Vendor invoices arrive through a Postmark inbound email address or a manual upload, and Claude vision extracts the fields. A project manager reviews each one, and approved invoices post straight to QuickBooks Online as Bills, PDF attached and project tagged. It runs on FastAPI and PostgreSQL behind self-hosted Logto auth, with Cloudflare R2 for document storage, deployed on Coolify.
Results
Invoices that post themselves
Vendor invoices arrive by email, get read by Claude vision, pass a PM’s review, and land in QuickBooks Online as Bills with the PDF attached and the project tagged.
A front door that matches the work
The marketing site leads with the firm’s record: a decade in business, 350+ projects, and an unlimited Tennessee contractor license.
Stewardship
The engagement continues post-launch. RelentNet hosts the marketing site and AP portal on production infrastructure, monitors their availability and performance, maintains security patches and dependency updates, and supports the Cambridge team as both systems power their daily operations.
Built with
15 tools across the marketing site and the AP portal
Marketing Site
- React 19
- TanStack Router
- Tailwind 4
- Motion
- Vite 7
Invoice Portal
- FastAPI
- PostgreSQL 16
- SQLAlchemy 2
- Alembic
AI & Integrations
- Claude (vision)
- QuickBooks Online
- Postmark
Ops & Storage
- Logto
- Cloudflare R2
- Coolify
In their words
A letter from the client
Brandon Harris and RelentNet were contracted by our startup construction company to develop a website. The design and data-collection process was detailed and required significant feedback from my team, as should be expected with a project of this nature. The final website was right on par with what we were promised, and the craftsmanship and attention to the small details—animations, transitions, and other design elements—went well beyond what we had expected.
Less than a year after completing the website, we engaged Brandon to develop a web-based solution that would allow our team to digitally process the miscellaneous invoices we receive each month. Our initial request was, at best, vague regarding our ultimate expectations for functionality. We were really only able to explain how our existing "paperless" process worked for receiving, coding, approving, and filing PDF invoices.
What Brandon ultimately delivered was far beyond anything we had envisioned. We are very excited for the possibilities this type of technology could provide as our company continues to grow. Brandon created a fully functional, scalable solution that automates most of the invoice process from receipt to pushing data and documents into QBO, notifies team members when an invoice requires attention, and sends a daily reminder at a designated time if their review has not been completed. He even figured out how to integrate a digital "stamp" reflecting the job-cost coding, approver, and approval date.
The design process was practically painless for our team. Brandon listened carefully to what we needed, understood what we were trying to accomplish, and then worked his digital magic to turn our ideas into a highly functional solution. He was able to take a relatively basic description of our existing process and transform it into something significantly more sophisticated and efficient.
We would highly recommend Brandon Harris and RelentNet for any bespoke coding or technology project. We could not be happier with our investment, the products he has delivered, or the continued support Brandon has provided throughout beta testing and our ongoing daily use of the system. He has proven to be an exceptional partner who not only delivers what he promises, but he also consistently finds ways to deliver more than we ever thought possible.

Who built it
Brandon Harris
Co-founder & CEO, RelentNetNashville
Brandon owns what gets built: the vision, the code, the design. RelentNet still hosts and maintains both Cambridge systems.
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