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Jonathan Tollefson
Design Engineer
jtollefson123@gmail.com · (614) 403-4845 · uxjon.com · linkedin.com/in/jtollefson123 · Minneapolis, MN

Summary

Design engineer working the seam between interface design, front-end, and applied AI. Sole designer, builder, and shipper of an agentic audio-mastering system, and of the blind evaluation harness that gates it, built after hitting the known failure mode of these systems: the evaluator, not the model, sets the ceiling on quality. Before that, enterprise AI at a Fortune 500 cooperative, a B2B SaaS AI platform, and a bilingual banking launch that cut onboarding bounce from 40% to 25%, designing with engineers rather than handing off.

Selected Builds

Finishable — the Engineer · AI mastering agent
2026 – Present
  • Built an AI mastering system that works as an agent, not a button: it takes actions and carries state across a multi-step run, rendering several masters, running a blind, loudness-matched A/B (ITU-R BS.1770, true-peak controlled), and composing a final master from the strongest takes.
  • Built an active-learning model of my own taste, then shelved it: blind A/B results showed it overfitting a biased evaluator, the known reward-model overoptimization failure.
  • Moved the work into the judge instead: a blind, loudness-matched harness that gates every change against a baseline of doing nothing. Single-rater so far; a multi-rater blind run is the next gate.
  • Designed and shipped end to end, no handoffs: Astro, React, TypeScript, Python, FastAPI.
Interactive case study: uxjon.com/case-studies/the-console
Finishable — the Catalog · audio catalog and search
2026 – Present
  • Built a searchable catalog of roughly 20,000 audio files, read by sound, fingerprinted, deduplicated, and auto-classified through a Whisper, Claude, and librosa pipeline. Sole engineer across ingestion, classification, and interface.
SIGNAL · browser instrument
2026 – Present
  • Built a playable instrument that runs in a browser tab: Web Audio synthesis, sequencing, and a performance layer, with the sound engine and the interface designed as one system. It lives on my homepage; press power.
Play it: uxjon.com/#play

Experience

CHS Inc. · Business Analyst, AI & BI Engineering
Aug 2023 – Present
  • Designed and prototyped interfaces for enterprise AI and BI products at a Fortune 500 agricultural cooperative, embedded with engineering on consumer agri-tech tools and internal AI tooling.
  • Designed a FigJam-based documentation and alignment system adopted as the cross-team default across product, engineering, and business.
  • Built and shipped a Python tool that parses the dbt manifest and fans model lineage into Excel, Power BI, and stakeholder briefs in one pass; owned it end to end for business users, engineers, and the AI team.
Raylu, Inc. · Product Designer (Freelance)
Jan – Oct 2023
  • Designed the interface, component set, and interaction model for a B2B SaaS AI chat platform, specified so the patterns mapped 1:1 to the React implementation.
  • Ran the roadmap for a distributed team shipping prototype releases on a tight cycle.
Crediverso · UX Design Lead
Feb 2021 – Jan 2023
  • Designed the primitives, patterns, and onboarding flows for a bilingual mobile banking V1, shipped on iOS.
  • Ran usability testing with 50+ participants; the iterated primary flow cut bounce from 40% to 25%.
  • Grew the pre-launch channel from 700 to 2,100 followers on A/B-tested messaging.

Education

Harvard University
2022
A.B., Sociology
Dean's List (6×) · Rosenkrantz Discovery Grant
University of Minnesota
2016 – 2018
Product Design, Business Marketing Education

Skills

Build: TypeScript, React, Astro, Python, FastAPI · Design: Figma, Framer, Adobe Creative Suite
Models & Audio: Web Audio API, Claude, Whisper, librosa, demucs · Data: SQL, dbt, Power BI
OutsideDiary of a Soundbender, a Substack on sound and product design. Track and field record holder, University of Minnesota.