Fairfield County, CT

Charlie Petch

Engineer & Inventor

I build open-source tools, AI systems, and optimization engines.

About

The through-line in my work is building things people actually use: a Markdown typesetting studio, a browser-based optimization workbench, an NLP platform adopted by 5,000+ employees. By day I'm a senior software engineer in Fortune 50 healthcare, working on GenAI and modern data platforms. Three U.S. patents in NLP and optimization along the way.

Projects

Cipher Station

Self-hosted, distributed storage protocol built on IPFS — quantum-safe encryption and pinning across the network for resiliency. The foundation beneath CipherVault and CipherFrame. Free and open source.

PythonIPFSEncryption

cipherstation.io →GitHub →

CipherVault

Self-hosted, post-quantum encrypted file store for iOS, built on Cipher Station. Files are encrypted on-device before upload, paired across stations, shared with followers, and locked behind Face ID. Free and open source.

SwiftiOSPost-Quantum Crypto

GitHub →

CipherFrame

Self-hosted, post-quantum photo and video network for iOS, built on Cipher Station — an Instagram-style feed with no company in the middle and everything encrypted before it leaves your control. Free and open source.

SwiftiOSPost-Quantum Crypto

GitHub →

mdstud.io

Turn Markdown into typeset, print-ready documents in the browser — themes, editable charts, Mermaid diagrams, and PDF export that matches the preview exactly. Local-first: no account, no server. Free and open source.

TypeScriptMarkdownLocal-first

mdstud.io →GitHub →

EPICAC

Excel Solver, rebuilt for the browser: HiGHS LP/MIP plus custom high-performance Rust GRG and evolutionary engines compiled to WebAssembly — with live telemetry, run history, and solution insights. Free and open source.

RustWebAssemblyOptimization

epicac.app →GitHub →

Patents

Skills

AI & Machine Learning

LLMs / GenAIRAG & GraphRAGAgentic Engineering (Claude Code, Cursor)NLPKnowledge GraphsExplainable AI (SHAP)PyTorchXGBoostMLflow

Data & Platforms

PythonSQLDatabricks (Medallion, Genie)Neo4jVector Search

Analytics & Leadership

Causal InferenceExperimentation DesignNon-linear OptimizationMeasurement FrameworksTeam Leadership

Experience

Senior Software Engineer
Jan 2025 – Present
The Cigna Group
- Ship RAG systems for classification and chat, from vector search to GraphRAG.
- Architect a Neo4j knowledge graph unifying Workday, Jira, Confluence, and ServiceNow — with people as the central node.
- Migrate legacy SQL platforms to Databricks medallion architecture, curating metadata for Genie.
Market Insight Senior Manager
May 2023 – Dec 2024
The Cigna Group
- Built and led a 9-person data science team across go-to-market segments.
- Unified first- and third-party data into one measurement framework — 15% campaign lift.
- Modeled MDLive engagement propensity with XGBoost to prioritize ad spend, explained with SHAP.
- Ran A/B and holdout experiments that shaped leadership decisions.
Product Strategy Senior Advisor
Jul 2021 – Apr 2023
The Cigna Group
- Replaced vanity metrics with causal outcome attribution.
- Product Strategy for MDLive site of care steerage, saving nearly $2M/year.
- Built analytics infrastructure reused across the enterprise.
IT Senior Advisor
Apr 2020 – Jun 2021
The Cigna Group
- Built Pathfinder, an NLP + optimization platform used by 5,000+ employees to route project demand.
- Optimized project portfolios for value within IT Finance constraints.
- Earned three U.S. patents; advised the CIO with simulation-driven recommendations.
IT Project Manager
Jun 2016 – Mar 2020
Express Scripts
- Delivered 18 cross-functional projects totaling $7.5M.
- Built the proof of concept for PMO centralization — adopted by Accredo, then enterprise-wide.
- Automated weekly reporting, lifting team throughput 20%.

Education

BA, Business Administration & Economics

Principia College

Contact

Email charliepetch@gmail.com or connect on LinkedIn.