I build evaluated AI systems and financial research tools: cited retrieval over SEC filings, financial QA evaluation, and risk analytics with inspectable inputs and calculations.
Computer Science + Quantitative Finance at NUS. Based in Singapore.
Site: johan-vaz-site.vercel.app — several projects below are deployed and clickable, not just readable.
Currently: looking for internships or junior roles in AI agents, LLM evaluation, fintech, or quant research tooling — ideally on a small team that ships.
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Apache Arrow — more reliable numerical data imports. Fixed CSV values such as
+1and+1.5being mistaken for text; added tests for valid numbers, overflow, and malformed input. Reviewed and merged into the official Rust implementation on 17 September 2026. -
Apache Arrow — faster selection for fragmented masks. Added adaptive dispatch to the existing interleave kernels while preserving null handling and the contiguous-mask path. The PR's 8,192-row i32 benchmark recorded 76.889 µs → 33.676 µs, a 56.2% reduction in execution time for that workload.
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bt — integer allocation with nonlinear commissions. Fixed a search that skipped an affordable share quantity and raised an error; added a regression for minimum, per-share, and capped commissions.
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ffn — multi-period annualization. Corrected frequency inference that inflated annualized ratios for 30-minute data, with coverage of the resulting Sharpe calculation.
The linked PRs contain the implementation, review discussion, validation, and any AI-assistance disclosures. Benchmark results apply to the recorded workloads and environment.
| Project | What it is |
|---|---|
| AI Equity Research Copilot | Document-grounded research over SEC filings: EDGAR ingestion, chunk-level cited retrieval, structured memos — plus a finance QA eval set so citation precision, refusals, and hallucination risk are measured, not assumed. |
| Financial LLM Eval Harness | 50-case evaluation suite for financial QA systems: factual extraction, multi-document synthesis, refusal behavior, adversarial prompts, scoring, and regression reports. |
| Curio | Learning-by-teaching, instrumented: teach an AI novice by voice, reasoning agents map your claims against a curriculum, then the novice teaches it back using only what it learned from you. |
| FluentAI | Agentic language tutor with adaptive lessons, evaluator/memory agents, real-time speech, and spaced repetition driven by actual conversation mistakes. |
| finance-labs | A toolkit of small, offline, test-covered risk and market-structure diagnostics: margin cascades, ETF liquidity stress, option skew, factor crowding, covenant headroom, and more. Live results gallery → |
| US Market Regime Dashboard | Macro/risk context dashboard with transparent regime rules, data-freshness checks, and exports. FastAPI + React. Live → |
| Portfolio Risk Copilot | API-first portfolio risk: VaR, expected shortfall, correlations, concentration flags, stress tests, plain-English commentary. Live → |
- Email: v.johan2234@gmail.com
- LinkedIn: sg.linkedin.com/in/johan-vaz