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2M+ learners, the Lumi tutoring agent, LLM-graded code evaluation, 387 merged PRs
Apps2022–2026- Problem
- Joined a pre-revenue learn-to-code startup as its first engineer, with the platform still to build.
- Decision
- Built it from scratch in Next.js and TypeScript on Firestore, with one component system for every surface and Braintrust tracing on the LLM features.
- Outcome
- Used by 2M+ learners at $100k MRR; about 65% of the code in production is his, across 387 merged PRs.
- Built with
- Next.js, TypeScript, Firestore, Firebase, Google Cloud, Styled Components, Design systems, Vercel AI SDK, Genkit, Gemini, Vertex AI, RAG, Tool calling, Streaming responses, Structured outputs, Braintrust, LLM evals, Stripe, PayPal, GitHub Actions, MDX, WebSockets
Guardrails, a 500-case eval suite in CI, prompt tokens cut by over 50%, WebMCP tool calling
AI2026–now- Problem
- Non-engineers ask it about data from 70+ Rakuten Group businesses, and every answer has to stay on scope and keep PII out.
- Decision
- Built a guardrails layer on what goes into the model and what comes out, and brought in LangSmith for versioned prompts, a 500-case eval suite in CI and tracing.
- Outcome
- Passes the team’s full red-team set, with system prompt tokens cut by over 50% and the eval suite as the regression gate, all in the first month.
- Built with
- LLM guardrails, LangSmith, LLM evals, Golden-set regression testing, Natural language to query, WebMCP, Tool calling, Chrome Built-in AI
AI form checker for lifters, on the App Store since 22 October 2026
MobileLive- Problem
- A lifter who films a set wants every rep scored, and to know what to fix next session.
- Decision
- Cloud Functions send each clip to Gemini via Genkit for a score out of 100, rep grades and timestamped pointers; RevenueCat subscriptions are checked on the server.
- Outcome
- On the App Store since 22 October 2026, with version 1.1.0 out on 28 October; 225 of its 233 commits are his.
- Built with
- TypeScript, React Native, Expo, Expo Router, Tamagui, Zustand, Firebase, Firestore, Cloud Functions for Firebase, Genkit, Gemini, RevenueCat, Jest, Next.js, Tailwind CSS, Playwright, Vercel, GitHub Actions
Public TestFlight beta; tone accuracy evaluated per Monk Skin Tone group
MobileBeta- Problem
- One selfie has to become a morning and night face-care routine that holds up across skin tones.
- Decision
- Gemini on Vertex AI reads the selfie, tested rules pick every routine step, and the model only writes the wording, screened by a term blocklist.
- Outcome
- In public TestFlight beta for adults 18+; a model change ships only after the Monk Skin Tone eval passes.
- Built with
- TypeScript, React Native, Expo, Expo Router, Tamagui, Zustand, Firebase, Firestore, Cloud Functions for Firebase, Gemini, Vertex AI, Vercel AI SDK, Zod, RevenueCat, Jest, Next.js, Tailwind CSS, Playwright, Vercel, GitHub Actions
Study-pack builder: Claude on AWS, RAG over S3 Vectors, a pass@k eval harness
AILive- Problem
- Claude turns a PDF, a photo of notes or a text file into flashcards, a quiz and a summary, in calls that outlive API Gateway’s 30-second cap.
- Decision
- A presigned S3 upload fires an event to a processor Lambda; /ask runs RAG on Titan V2 embeddings in S3 Vectors, filtered to the caller’s user id.
- Outcome
- Live, with a public repo and a pass@k prompt eval harness that includes a prompt-injection canary.
- Built with
- TypeScript, Next.js, React, CSS, Node.js, AWS, AWS CDK, AWS Lambda, Amazon S3, Amazon S3 Vectors, DynamoDB, Amazon API Gateway, Amazon Cognito, Amazon Bedrock, AWS Systems Manager, AWS Amplify, Claude API, Vercel AI SDK, Zod, Vitest, Vercel
2018
1 contribution · one dot
The GitHub account Goku-kun opens on 4 November 2018.
He opens the GitHub account Goku-kun on 4 November 2018, while studying Information & Communication Technology at Pandit Deendayal Energy University. One contribution that year.
2019
47 contributions · one dot each
Top 25 of 16,000 at TCS EnginX, and a first merged open-source PR.
- 1000 Ways to Print Hello WorldFirst-timers repo: 111 merged PRs from 86 authorsOpen SourceRepo
2020
444 contributions · one dot each
Learning in public: contributions jump from 47 to 444.
- Merged PRs into argonautica/sorting-algorithms (recursive bubble sort in Python) and Hacktoberfest2020-Expert (4 October)
- AQI classifier for India's National Air Quality Index bands across 8 pollutants
- Ajia Bunker Bot: a Python Discord bot with quotes, dad jokes and encouragement for sad messages
- Silly Hacks 2020: his part of a team's co-op game concept, Lavish
- 18 learning repos: Python, data science, CTFs, Project Euler and web basics
2021
1,078 contributions · one dot each
A BTech with a CGPA of 8.91, and the first shipped apps.
- boilerplatenodeZero-dependency Node.js CLI, published on npmToolsLive
- JavaScript PresentationsSlides for a 2021 series of JavaScript talksTeachingRepo
- Cell Characterization ApplicationFinal-year project: Keras classifies cells in micrographsAIRepo
- SendifyFile sharing with Google sign-in, around Discord’s 8 MB capAppsLive
- E-commerce Product PageTeam build in React, Redux Toolkit and FirebaseAppsLive
2022
1,462 contributions · one dot each
First engineering hire at Codédex, after a summer teaching at BloomTech.
- Web Development Instructor, Bloom Institute of TechnologyMay–Aug 2022
- Founding Software Engineer, CodédexJun 2022–Jul 2026
- Merged PR into styled-components (February)
- Codecademy article: An Introduction to Abstract Data Types in JavaScript (May)
2023
2,514 contributions · one dot each
The busiest year: 2,514 contributions and 169 merged platform PRs.
- Codédex Chat AppCodédex tutorial: real-time chat with Express and Socket.IOTeachingRepo
- Intro to Git and GitHubDemo repo for a Codédex Git and GitHub workshopTeachingRepo
2024
2,026 contributions · one dot each
Codédex wins Phenomenal Education Partner at the GitHub Awards 2024.
- Retro WebsiteHoliday hackathon workshop: script a 90s-style web pageTeachingLive
2025
2,335 contributions · one dot each
Two Codédex tutorials, an npm 1.0.0 and a game that rewinds.
- AI Agent TemplateTypeScript CLI agent with Zod-typed tool callsAIPrivate
- Air JugglerCodédex tutorial: keep a ball in the air with your webcamTeachingLive
- next-url-rewriteRule-based URL rewriting for Next.js middleware, on npmToolsLive
- Route Optimization SystemPlans delivery routes with OSRM, nearest-neighbor and 2-optAppsPrivate
- Text-to-Speech AppCodédex tutorial: a text-to-speech app on the Web Speech APITeachingLive
- RewinD FlappyFlappy Bird in Flutter and Flame, with a five-second rewindMobilePrivate
2026
1,809 contributions · one dot each
Applied AI Engineer at Rakuten, Tokyo, and co-founder of DA App Ventures.
- File OrganizerGo CLI that sorts files by extension, month or sizeToolsRepo
- fahhhGo CLI that plays the ‘fahhh’ sound when a command failsToolsRepo
- Pixel Art MakerCodédex tutorial: a pixel-art editor on HTML CanvasTeachingLive
- Build Your First AI AgentWorkshop code: build a TypeScript CLI agent in 60 minutesTeachingRepo
- Steel Ball SpinWebcam toy: open your palm and a steel ball spins over itFunLive
- Intro to Claude CodeSlides for a 60-minute hands-on Claude Code workshopTeachingPrivate
- Canvas Typography with PretextCanvas text that reflows around draggable imagesTeachingRepo
- AtlasMulti-persona AI chat on Next.js and GeminiAIRepo
- EngramClaude turns a PDF, photo or text file into a study packAILive
- HeadHuntRecruiting SaaS where Claude scores candidates, with evidenceAIPrivate
- Prompt Engineering 101Slides for a 60-minute Codédex prompt engineering workshopTeachingLive
- SpotterGemini scores a filmed lift rep by rep, on the App StoreMobileLive
- GlowSelfie face-care app on Gemini, in public TestFlight betaMobileBeta
Toolbox
, , , , , , , , and . In 2026, the AI layer: , , and LangSmith at Rakuten.