William Callahan

CFA Charterholder · CFP® Professional

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San Francisco, Californiawilliamcallahan.comaventure.vc
X (Twitter)@williamcallahanlinkedin.com/in/williamacallahan

Professional Summary

Software engineer and leader experienced in data, search, finance, and AI-powered web applications. Deep background in product development and quantitative research.

Highlighted Technical Projects

aVenture.vc

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AnalyticsData PlatformResearch ToolBusiness IntelligenceSaaSWeb Application

Private-market research platform indexing tens of millions of records across 500+ attributes, with live ETL that ingests news, company data, and investor updates daily. Built with Node.js, Next.js, TypeScript, Zod, PostgreSQL, and supporting services.

williamcallahan.com

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Graph IndexS3 Object StorageInteractive AppTerminal UIMDX BlogSearch

Personal site with a graph index of thousands of JSON documents that crawls external links to fetch logos and OpenGraph images on demand. Built with the Next.js App Router and TypeScript; Dockerized for cloud deployment.

SearchAI

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AIWeb SearchChat AssistantOpenAIGPTRAG

Web app that merges search with an AI chat assistant: select results, then ask GPT/Groq/Gemini using that grounded context. Built with Next.js, TypeScript, Convex Database, and Vercel AI SDK, with heavy server-side scraping/parsing to filter only relevant context.

ComposerAI

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AIEmail ClientLLMProductivityTask AutomationVector Search

AI-native email client that indexes every message in Qdrant for semantic and BM25/BM42 search. Offers full-mailbox search, drafts cited replies, and surfaces follow-up tasks from context. Built with Svelte + Vite and Spring Boot.

Brief

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Terminal UICLIChat ClientOpenAIJavaOpen Source

Terminal ChatGPT client for fast, keyboard-first chat. Includes slash commands, tool execution, and support for OpenAI-compatible providers (OpenRouter, Ollama, LMStudio). Location features powered by Apple Maps Java. Built with TUI4J and available via Homebrew.

TUI4J

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Terminal UITUIJavaOpen SourceDeveloper ToolsFramework

A Java terminal user interface framework inspired by Charm's BubbleTea (Go). Implements The Elm Architecture with Model/init/update/view patterns. Includes ports of bubbles (UI components), lipgloss (styling), and harmonica (spring physics animations). Published on Maven Central.

Apple Maps Java SDK

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JavaSDKApple MapsGeocodingREST APIOpen Source

A lightweight, unofficial Java SDK for the Apple Maps Server API. Provides geocoding, search, autocomplete, directions, ETA, and place lookup for backend/JVM applications. Automatically exchanges long-lived JWT tokens for short-lived access tokens with refresh. Published on Maven Central.

Professional Experience

  • aVenture2023 - Present
    Founder & CEO
    ·San Francisco, California·aventure.vc
    • Building a research platform with data on venture-backed startups and their investors to help founders and investors make better decisions
    • Backed by Techstars
  • TS Bank2021 - 2022
    President, wealth management division
    ·San Francisco, California / Omaha, Nebraska·tsbank.com
    • Led unit following acquisition/sale of Callahan Financial Planning
  • Callahan Financial Planning2010 - 2021
    Founded and led an SEC-registered investment advisor
    ·San Francisco, California / Omaha, Nebraska·tsbank.com
    • Provided comprehensive financial planning and investment advisory services, including proprietary cloud software for managing complex/nuanced data sets in such relationships
    • Managed $225 million in assets on acquisition
  • Mutual First Federal Credit Union2020 - 2021
    Board member
    ·Omaha, Nebraska·mutualfirst.com
    • Served on the board of directors, including as treasurer, overseeing the strategic direction and financial health of the credit union
    • Primary focus on product differentiation and pricing strategy, asset-liability management strategies, and growth strategy
  • Morningstar2015 - 2019
    Advisor to the executive team
    ·Chicago, Illinois·morningstar.com
    • Provided strategic and specific direction to the executive team on the development of new SaaS offerings for advanced investment research and portfolio management

Education

  • Creighton University2016

    Master of Investment Management & Financial Analysis (MIMFA)

    Omaha, Nebraska

  • Creighton University2016

    Master of Business Administration (MBA)

    Omaha, Nebraska

  • University of Nebraska2011

    BSBA in Corporate Finance, Banking & Financial Markets, Investment Science & Portfolio Management

    Omaha, Nebraska

Selected Programming Coursework

  • Programming Methods - Java2025
    College of San Mateo
  • Object-Oriented Programming - Java2025
    College of San Mateo
  • Python Programming2025
    College of San Mateo
  • Unix & Linux Systems2025
    College of San Mateo
  • Data Structures & Algorithms2025
    College of San Mateo
  • Web Development (JavaScript / TypeScript)2025
    University of California Berkeley
  • Machine Learning for Business with Python2024
    Stanford University
  • Large Language Models for Business with Python2024
    Stanford University
  • User-Centered Design for AI Applications2024
    Stanford University

Certifications & Professional Development

  • Executive Education – Venture Capital Decision Making

    Columbia Business School• 2022• New York, New York

  • Certification in Startup Law & Venture Capital Investing

    University of California Berkeley• 2022• Berkeley, California

  • Chartered Financial Analyst (CFA) Charterholder

    CFA Institute• 2016• Charlottesville, Virginia

  • Certified Financial Planner (CFP) Professional Certification

    CFP Board• 2012• Washington, District of Columbia

Technical Focus

Languages & platforms

  • TypeScript (JavaScript)
  • Java
  • Python
  • SQL
  • PostgreSQL
  • Qdrant

Frameworks & runtimes

  • Next.js
  • Node.js
  • React
  • Svelte
  • Spring Boot
  • Vite
  • Docker

AI systems & data

  • Hybrid search (BM25/BM42 + embeddings)
  • Retrieval-augmented generation
  • LLM tool chaining
  • Vector indexing
  • Self-hosted LLM inference
  • Semantic meaning extraction

Investment, finance, & risk analytics

  • Asset-liability management
  • Quantitative research
  • Factor modeling
  • Portfolio optimization
  • Performance attribution

Last updated: November 8, 2025

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