Developer Showcase
AI-generated narratives and infographics exploring the development history of selected projects.
Developer Portfolio Overview
Cross-project portfolio covering 38 projects and 5668 total commits.
SwiftCLIKitAuth: Zero-Friction Account Sign-In for Swift Command-Line Tools
A modular authentication layer for SwiftCLIKit that establishes identity, asserts assurance, and admits users — from local terminals and over SSH — without knowing anything about how identity is proven.
SwiftWebAuthn: Server-Side Passkey Verification, Written From the Specification
A Swift package that implements WebAuthn's registration and authentication ceremonies on the server, built from the W3C specification so that passkeys can be the default way a person proves identity — not a fallback.
SwiftZIP: A Pure-Swift ZIP Engine With Zero Compromise on Dependencies
A from-scratch ZIP reader and writer built entirely on Foundation and Apple's Compression framework, shipping five releases in four months to serve as the archive backbone for SwiftXLSX and any Swift project that refuses to carry C baggage.
SwiftXLSX: A Pure-Swift Round-Trip Engine for Excel's Open XML Format
Building a bidirectional XLSX library from scratch in Swift — handling ZIP, XML, formula parsing, and strict concurrency — across 47 releases in under a month.
GeoSEOMCP: Building the Audit Layer for the Post-Search Web
A Swift MCP server exposing 29 tools that answer the question traditional SEO never asked: not *can a search engine rank this page*, but *can an AI system understand, retrieve, and correctly cite it*?
SwiftOAuthCore: Both Halves of OAuth 2.0, One Swift Package
A solo Swift library project that tackles OAuth's two distinct roles — server and client — in a single, storage-agnostic package, built to eliminate the authentication gap in an ecosystem of Swift services and MCP clients.
CorpusKit: The One True Writer for a Quality Gate Corpus
A disciplined single-implementation library that owns every read and write operation on a shared telemetry corpus, preventing schema drift before it can begin.
BusinessMathMCP: Giving AI Agents a Calculator They Can Trust
A production MCP server that wraps a battle-tested Swift financial library into a large, coherent tool surface — so AI agents can compute discount rates, run statistical models, and perform valuations without estimating.
Streaming Giants: Building a Pure-Swift MoE Inference Engine for Apple Silicon
In seven months and 187 commits, jpurnell built a production-grade inference engine capable of streaming 200GB+ language models through a custom Metal compute pipeline while holding just ~6GB in resident memory — no Python, no C, no compromises.
SwiftExcelFunctions: Excel's Formula Library, Rebuilt for Swift
A single-registry function evaluator that speaks Excel's exact semantics — no file format required, no math reimplemented, no room for silent divergence.
The Double Compile: Making a Swift Quality Gate ~16× Faster Without Weakening a Check
How parallelizing the run loop, a provably-safe result cache, and — the big one — discovering the gate was compiling every project twice took a SwiftSyntax + IndexStoreDB quality gate from ~262s to ~16s cold, with zero suppressions.
development-guidelines: A Versioned Rulebook That Enforces Itself
A vendorable, AI-readable specification for Design-First TDD in Swift — where every rule that can be checked has a quality gate behind it, and every rule that failed in practice carries its own evidence.
IconquerCLI: Wiring a Package Ecosystem Into a Playable Terminal Strategy Game
A thin executable backed by a composable library, IconquerCLI brings a Risk-style LLM-powered board game to the terminal by integrating five purpose-built Swift packages into a single cohesive experience.
IconquerCore: A Headless Rules Engine Built to Last
J. Purnell distilled a complex turn-based strategy game into a pure-Swift, platform-agnostic rules engine — versioned deliberately, architected for reuse, and designed so that any future client can consume it without touching the core logic.
IconquerMatch: Orchestrating the Space Between Rules and Players
The match orchestration layer that wires agents, deadlines, and a rules engine into a complete, replayable game — without knowing or caring how any move was produced.
ProjectShowcase: Building the Tool That Writes Its Own Portfolio
A Swift CLI that extracts structured facts from developer projects and generates grounded, narrative case-study portfolios — turning artifacts that already exist into prose a technical reader would care about.
QualityGateCore: Building a Static-Analysis Gate That Enforces Its Own Rules
An 800-commit, eight-month construction of a SwiftSyntax-based quality gate for Swift 6 projects — modular by design, honest about its own debt, and strict enough to run its own checkers on itself.
SwiftMCPClient: A Production Swift Client for the Model Context Protocol
A solo developer built a spec-compliant, multi-platform MCP client in Swift 6 — shipping nine releases over seven months by making deliberate tradeoffs between purity and capability.
GEO Audit: Building a Paid AI-Visibility Scoring Service in Swift
A solo developer designed and shipped a three-layer Vapor application that scrapes websites, delegates scoring to a remote MCP server, and sells per-audit and subscription monitoring plans — all in under eight months.
SwiftMCPServer: Owning the Protocol So Consumers Don't Have To
A production-grade Swift implementation of the Model Context Protocol server with HTTP transport, designed so that the engineers building on top of it never have to think about framing, authentication, or the wire.
SwiftCLIKit: A Pure Swift Terminal UI Framework Built for the Modern Concurrency Era
From zero to 23 releases in six months, jpurnell built a production-grade terminal UI library — with an embedded SSH server — that makes no compromises on Swift 6 strict concurrency and zero C dependencies.
SearchOperatorCore: Making Google's Advanced Search Syntax Accessible to Humans and AI Agents
A Swift CLI tool and MCP server that abstracts the complexity of Google's advanced search operators into a structured, programmable interface — built for power users, researchers, and the AI agents working on their behalf.
A Personal Site That Fails at Compile Time, Not at Midnight
Justin Purnell rebuilt his personal website as a Swift package — turning broken pages into compiler errors and publishing into a single terminal command.
The Living Archive: Building a Portfolio-Wide Quality Telemetry Corpus
jpurnell designed and maintains org-judgement-corpus as the persistent, append-only data backbone for a portfolio-wide Institutional Judgment System — a structured record of every quality-gate run across dozens of Swift projects, stretching from April to November 2026.
Potrace in Pure Swift: Building the Algorithm from the Paper Up
A faithful, MIT-licensed Swift port of Peter Selinger's Potrace bitmap-tracing algorithm — derived from the original research paper rather than the GPL C source, making it the first permissively licensed, native Swift path from raster to Bézier.
IJSCore: Encoding Institutional Judgment as Enforceable Tooling
A Swift library that transforms quality gate telemetry and manual overrides into a self-reinforcing organizational memory, preventing AI-assisted development teams from repeatedly rediscovering the same hard lessons.
IconquerGameKit: The Single Integration Point That Keeps Every iConquer App Honest
A shared game brain that wraps three independent packages into one observable interface, ensuring every iConquer platform shell runs an identical turn loop with no reimplementation required.
Bridging the Transport Gap: IconquerClient's Transparent Remote Play Architecture
A SwiftNIO-backed WebSocket client library that makes a remote iConquer game session indistinguishable from a local one — and refuses to be less secure than its URL implies.
IconquerMCP: Giving AI Agents a Game to Play
An MCP server that wraps a deterministic turn-based strategy engine, letting AI agents create, join, and compete in full multiplayer games through standard Model Context Protocol tools and resources.
IconquerServer: Building a Server-Authoritative Multiplayer Backend in Swift 6
A SwiftNIO WebSocket server that acts as the canonical referee for iConquer, a turn-based territory-conquest game — validating every move, brokering lobbies, and serving humans and AI agents over the same wire protocol.
IconquerAI: Building a Measured, In-Process AI Opponent Engine in Pure Swift
In six months and 98 commits, one developer took IconquerAI from a blank repository to a versioned, multi-platform Swift package shipping trained model weights, a self-play training pipeline, and statistically rigorous benchmarking — all without a single unsound performance claim.
One UI to Rule Every Platform: Building IconquerUI as a Cross-Platform SwiftUI Library
A single SwiftUI presentation layer that powers a Risk-style strategy game across iOS, macOS, tvOS, and visionOS — without duplicating a line of UI code.
Resurrecting iConquer: A Design-First Swift Port of a Classic Mac Strategy Game
Justin Purnell is rebuilding a beloved 2002 Mac strategy game from scratch in modern Swift — using a TypeScript reference implementation as a behavioral specification and targeting iOS 26's Liquid Glass aesthetic as the finish line.
Applesoft BASIC Lives Again: A Faithful Interpreter for Modern Swift
A ground-up reimplementation of Applesoft BASIC in Swift 6.2 that treats historical fidelity as a hard requirement, not an aspiration — built to celebrate Apple's 50th birthday.
ApplesoftBASICAppCore: Bringing the Apple II Back to Life on Modern Hardware
A native Swift package powering a faithful Applesoft BASIC runtime across iPad, Mac, and Vision Pro — complete with graphics, sound, and period-accurate presentation.