Walter Marshall

Founder · Sole engineer Jacksonville, FL · Remote

• Designed and built a dealer management platform (recon, inventory, sales and CRM, service, parts, accounting) on one Flutter codebase for iOS, Android and web, about 50,000 lines of Dart. Pre-launch.
• Wrote the whole backend: 37 Cloud Functions on Node.js and 900+ lines of Firestore security rules that isolate each dealership’s data, plus role-based access across ~40 permissions and two-factor login.
• Modeled the recon shop as a seven-stage pipeline with day targets, so late vehicles get flagged automatically.
• Built for bad signal: offline caching, queued photo uploads, VIN and barcode scanning, e-signatures, audit log.

Customer Service Representative · Federal student aid accounts Remote

• Resolve account issues for federal student aid borrowers end to end, fully remote, under federal privacy rules.

Mechanic · Ford dealership, Greg’s Auto Body Collision Center On site

• Learned the recon and service workflow that Dealer Recon Systems is built around.

Software Engineer · Contract Remote

• Closed a catfishing exploit in the Android app (modified builds faking live camera photos) with a per-version integrity hash checked at login. Tampered clients failed silently, so the exploit’s authors couldn’t tell what changed.
• Designed the UI and UX for Kik X, a full redesign of the app.

• Hindsight (TypeScript, Electron): free, offline chess game review. Runs Stockfish in parallel, grades every move and explains mistakes by finding the actual pin, fork or hanging piece. Installers for Windows, macOS and Linux; CI runs all 581 tests on all three.
• paeth (Rust) matches an independent PNG decoder pixel for pixel on all 162 valid PngSuite images. loupe (C) parses all 4,264 System32 binaries under ASan, UBSan and LeakSanitizer with no errors.
• unspool (Python) matches tshark across 1,290,282 packets; vinspect (Go) is tested on 6,516 real VINs.

• Rebuilt a working model of the 2003 Delta Force: Black Hawk Down engine from compiled x86 with no source or symbols, checked against the running game (predicted knockback 7.69 m/s, measured 7.7). ~210,000 lines, 826 tests.