• 50 pull requests merged into 31 open-source repositories totalling 479,000+ stars, including Astro, pandas, Black, raylib and Prefect.
• 15,200+ sales and 344k Robux (~$1.3k at the DevEx rate) in the past year from 3D accessories made on my own local-GPU generation pipeline.
• 1.57x faster LLM decoding at 16k context on an RTX 4090, found with a roofline built from measured hardware ceilings.
• ~120 AWS resources provisioned with Terraform to deploy a multi-provider GenAI gateway end to end.
• A Redis-compatible database engine from scratch in Java 21: ~100K writes/s and ~130K reads/s single-threaded.

A measurement framework for Qwen2.5-7B-Instruct on an RTX 4090. It finds where inference time goes, fixes the bottleneck, and tests how refusal works inside the network.

• Built a roofline from measured ceilings (947 GB/s, 157.5 TFLOP/s) with no fitted parameters. It showed the attention path copying the KV cache seven times per layer.
• Wrote a grouped-query decode path that reads each cached key and value once: 1.57x faster at 16k context, 1.65x at batch 32, with no measurable fidelity loss against an FP32 reference.
• Removing one residual-stream direction takes refusal on harmful prompts from 95% to 0-2.5%. Random directions of the same size do nothing.
• Paired ABBA benchmarks, and every headline number is a recorded run stored with its hardware, versions and commit. 173 tests.

Python · PyTorch · Transformers · CUDA

An LSM-tree key-value store written from scratch in Java 21. redis-cli, redis-py and Jedis connect to it unmodified.

• Storage engine shaped like LevelDB/RocksDB: write-ahead log, memtable, sorted SSTables, leveled compaction and bloom filters.
• ~100K writes/s and ~130K reads/s single-threaded (JMH, 100K keys). Bloom filters answer missing keys ~90x faster by skipping the disk.
• Speaks Redis's RESP protocol over TCP, with TLS, multi-user auth, pub/sub and snapshots.
• 209 tests, about 3,800 lines of Java plus 3,300 of tests.

Java 21 · LSM-Tree · RESP · Concurrency

A physics engine and a reinforcement-learning algorithm, both written from scratch. There's no physics library, no animation and no scripted trajectory.

• A 2D sequential-impulse constraint solver in C++: warm starting, speculative contacts, a Coulomb friction cone.
• PPO from scratch in PyTorch: clipped objective, GAE, advantage normalisation, KL early stop.
• The trained policy lands 24 of 24 backflips, and still lands 83% when shoved with 200 N·s mid-flight.
• 64 environments share one UDP datagram per control step. 313 tests (216 C++, 97 Python).

C++ · Python · PyTorch · OpenGL

Point one Rust binary at a folder of CT or MRI files and get a browser viewer with 2D slices and 3D GPU volume rendering.

• Slice order comes from each file's position in patient coordinates, never InstanceNumber, which lies in real data. A regression test shuffles instance numbers to prove it.
• Indexes headers only, never pixel data: a 1,026-slice study indexes in ~90 ms.
• Hand-written WebGL2 raymarching with a resolution pyramid, so a modest laptop loads 1 MB instead of 64 MB.
• 127 tests (67 Rust, 60 browser), plus 7 that run against real CT studies from the public NCI archive. MIT.

Rust · WebGL2 · axum · SQLite · TypeScript

Traces the Kaggle Heart Failure Prediction CSV back to its four UCI hospital sources and measures what that changes.

• Found that the filled-in missing values encode the diagnosis: every filled ST_Slope is Flat for heart disease (111 of 111) and Up without it (191 of 191).
• Undoing the fill drops the typical pipeline's median accuracy from 86.4% to 79.3% over 1,000 paired splits.
• A pre-registered survey of 30 public notebooks found 0 of 30 mention it. Every prediction was committed before its experiment ran, and 14 of 15 held up.
• Leave-one-hospital-out AUC is about 0.83. 77 tests, and all five notebooks run in CI.

Python · pandas · scikit-learn · pytest

Paste a TCGplayer link and get a whole-dollar sticker price for every condition, matched to what a buyer would pay online including shipping. I'm the sole engineer.

• Full stack on Cloudflare Workers, D1 and KV, with an hourly cron keeping prices current.
• Pricing engine written twice on purpose: a Python reference and the production TypeScript port, with golden tests asserting they match byte for byte.
• 371 automated tests. Deployed but not yet in service: Clerk auth and Stripe billing are wired in test mode.

TypeScript · Cloudflare Workers · D1 · Stripe · Python

Deployed AWS's multi-provider GenAI gateway reference design from an empty repository to a working, TLS-secured endpoint, as a task set by Cisco professionals at Riffyx Labs. The architecture is AWS's; the deployment was mine. It was stood up end to end and then torn down.

• ~120 AWS resources in Terraform: VPC, ECS Fargate, ALB, RDS, ElastiCache, WAF, Secrets Manager, Route 53 + ACM, remote S3 state.
• LiteLLM in front of Amazon Bedrock behind one OpenAI-compatible endpoint, with least-privilege IAM and per-key cost tracking.
• Traced a PII-masking defect in the Presidio sidecar to a dependency version, and fixed it with a controlled upgrade and regression tests.

AWS · Terraform · ECS Fargate · Bedrock · LiteLLM

50 pull requests merged into 31 repositories totalling 479,000+ stars. These are fixes in codebases I don't maintain, found by reading unfamiliar code, diagnosed by measurement and defended in review. The ten largest repositories:

Plus 35 more merges across OpenLayers, kornia, Unciv, node-gyp, Terser, SwiftFormat, Luau, MockK, OpenBot and 12 other repositories: full list on ethanstoner.dev.

Two worth reading in full: rakazo #322, where the reporter wrote "I cannot explain the root cause" and I narrowed it down by elimination, and trueforge #464, where a reviewer asked whether an abort was needed and I measured it instead of arguing: Promise.race frees the caller but leaves the socket open.

Landed, Founder & Solo Engineer · 2026 – Present
Built and deployed a card-pricing tool as sole engineer across product, infrastructure and testing. 371 automated tests; billing wired in test mode, not yet in service.

Roblox UGC, Independent Creator · 2025 – Present
Design and sell 3D avatar accessories made with a local-GPU generation pipeline: 15,200+ sales and 344k Robux (~$1.3k at the DevEx rate) in the past year.

Riffyx Labs, Engineering Mentee · 2025 – 2026
Deployed a multi-provider GenAI gateway on AWS end to end, provisioning ~120 resources with Terraform across ECS Fargate, RDS, ALB, WAF and Bedrock, with Guardrails and PII masking.

• Cal State San Marcos, B.S. Computer Science · Fall 2026 – 2030 (expected)
• Anthropic: Claude API, Amazon Bedrock, Vertex AI, Model Context Protocol (Advanced), Claude Code (all certificates)
• OpenAI Academy: Agents & Workflows, AI Foundations, Applied AI Foundations
• AWS Certified Cloud Practitioner (CLF-C02): exam in progress