Sahil Singh
Available for collaborations

I build AI products that ship - from zero to one, and to scale.

Software engineer currently building at Bolto (YC S23). Previously architected the Swarm engine at Spine AI (YC S23) and was a founding engineer at Sigiq.AI. I work on agent orchestration, LLM routing across 400+ models, real-time consumer backends, and multi-cloud infrastructure.

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Users reached
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LLMs routed
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Agents orchestrated
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Products shipped
Trajectory
Bolto · YC S23/ Spine AI · YC S23/ Sigiq.AI · Founding Engineer/ IIT Kanpur · B.Tech '24/ Google AI4SG · $30K Grant/ GDSC IITK · Founder/ Inter-IIT · Bronze/ Google Code Jam · Rank 794/
Selected work

Products I shipped end to end.

Each card opens a full deep dive - what I owned, what I built, and what's running in production. The external link goes to the live product.

By the numbers

Production systems, not vanity metrics.

Every figure is from a live system I owned end to end - users who paid, agents that executed, and exams that got predicted.

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Active students on Padhai.ai
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AI tutor interactions served
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Concurrent WebSocket connections
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Live canvas environments on Spine
$30K
Google AI4SG grant · top 1 of 1000+
99.9%
Uptime · zero-downtime blue–green deploys
Experience

Where I've shipped.

Software Engineer · Bolto (YC S23)

May 2026 - Present · New York / Remote
Current

Bolto is the AI-powered hiring and HR stack for engineering teams - sourcing, AI vetting, scheduling, payroll, and compliance in one place.

  • Building AI-driven engineer sourcing & vetting pipelines that ingest signal from public code and match candidates to companies at scale.
  • Owning full-stack slices across sourcing, technical assessment, scheduling, and the recruiter experience.
  • Bringing the agent-orchestration and LLM-routing playbook from Spine into recruiting workflows.

Software Engineer · Spine AI (YC S23)

Aug 2025 - Apr 2026 · Remote

Spine ships an AI research platform whose deep-research engine ranked #1 on Google DeepMind's DeepSearchQA benchmark. I owned the orchestration engine, model router, and large parts of the canvas runtime.

  • Architected the backend orchestration engine for Spine Swarm - 1–10 specialized agents per task, 500+ concurrent, parallel non-sequential execution at production scale.
  • Built the intelligent model router - 400+ LLMs selected dynamically per step, optimizing for quality, latency, and cost. Cumulatively processed 106k+ intelligence nodes.
  • Powered 6,400+ active canvas environments with collaborative agent execution, artifact persistence, branching, and full inspectability.
  • Shipped APIs that produce client-ready outputs - decks, PDFs, Excel models with formulas - and the React canvas frontend.
  • Owned multi-cloud DevOps (AWS / GCP / Azure) with zero-downtime blue–green deploys; took Spine 0→1 to 10k+ users · 151 paying · 2.5% conversion.

Founding Engineer · Sigiq.AI

Jun 2024 - Jul 2025 · Gurgaon

Founding-member SDE for the company behind Padhai.ai (UPSC, 175k+ users), EverTutor (K-12 + GRE), and a portfolio of AI tutoring products. Owned backend, infra, and reliability across the entire stack.

  • Owned the AI webserver behind Padhai.ai - comprehensive refactor and error-handling overhaul, with major stability gains under peak exam-season load.
  • Owned EverTutor's backend & infra end-to-end - integrated Stripe for international + domestic payments and unlocked the entire revenue path.
  • Led migration from PM2 processes to a containerized ecosystem; designed blue–green deploys with Docker for zero-downtime updates.
  • Built a 10,000-concurrent WebSocket microservice for real-time AI interactions, plus a separate CPU-intensive recordkeeping service to keep latency low.
  • Architected Datadog APM + centralized logging; shipped a Redis sorted-set leaderboard and a React Native markdown + LaTeX renderer for every tutor response.
  • Managed containerized microservices across AWS / GCP / Azure; led and mentored a team of interns.

SDE Intern · Sigiq.AI · PPO offered

Oct 2023 - May 2024 · Remote

Shipped React Native + Redux app features and Django APIs/websockets for AI chat; built a Redis cache leaderboard, an FCM notification panel (bulk send, CSV upload, Celery delivery), a deeplink-driven sharing pipeline with dynamic image generation, and a D3.js chat-graph visualization for conversation inspection.

SDE Intern · GIVA · PPO offered

May 2023 - Jul 2023 · Bangalore

Built mission-critical POS flows in Next.js + Node used in production across stores. Shopify order sync via APIs/webhooks, Razorpay payments, SearchTap reindexing. Discovered and fixed an indefinite-OTP verification flaw, hardening the mobile auth flow.

Cybersecurity Intern · Vaticinari & C3iHub IITK

Apr 2023 - Sep 2023

Built an Incident Response GUI from scratch using Volatility, Log2Timeline, and RegRipper for forensic timelines. Mapped adversary tactics with MITRE ATT&CK CASCADE, built an ETL log parser for Windows pktmon/tracerpt, and reverse-engineered WannaCry on Remnux to identify its kill-switch.

Earlier · Basta Neural & Centre for Teacher Accreditation

2021 - 2023

Full-stack dev at Basta (Razorpay integration, REST APIs in Node). At CTA, built a scoring + self-assessment web tool used by 400,000+ teachers across India - Pandas/NumPy scoring, Flask backend, Google Sheets integration via oauth2/gspread.

Projects & side quests

Funded research, awards, and experiments.

Full-stack experiments, security work, game dev, and published apps. Most link to source.

Google AI4SG · $30K2022

AI Labor-Room Smart Assistant

ASR-driven assistant for nurses in low-resource Bihar - timely documentation and complication detection. Funded with $30,000 from Google AI for Social Good (top picks from 1000+ global applications). Led a Flutter + Flask + ASR stack with custom KV-pair extraction.

Inter-IIT · Bronze2022

Solar Burst Identifier (ISRO)

Web tool for ISRO to identify solar bursts in X-Ray light curves at Inter IIT Tech Meet 10.0. ReactJS + ChartJS frontend, Flask REST APIs to a Python detection backend, downloadable CSV reports. Bronze medal.

Private repo · demo on request
GDSC IITK · Founder2023 - 24

Founded GDSC at IIT Kanpur

Founded and led the Google Developer Student Club at IITK - 1,000+ members, 9-member core, 50 volunteers. Ran ideathons (228 teams), GenAI workshops, Cloud Jam, and Winter Projects. 5,000+ event participants over the year.

Google Solutions Challenge2024

FeedHarmony

GDSC IITK's Solutions Challenge entry for global hunger - Flutter app + predictive ML. Managed Product, Dev, and ML teams to a working prototype in a 3-week deadline.

National scale2021

CTA Self-Assessment Tool

Scoring + self-assessment web tool used by 400,000+ teachers across India. Pandas + NumPy scoring algorithm on a Flask backend.

SPEC · IITK2021 - 22

IITK Sports Booking Portal

Online sports facility booking for IIT Kanpur post-COVID, scaled for 3,000+ campus residents. Flutter + Firebase Auth + Cloud Firestore.

CLI · DX toolingSide

Comet

AI-driven commit-message CLI in Python. OpenAI for context-rich messages, TextBlob NLP fallback when no API key, optional Jira ticket linking.

C3iHub · VAPT2023

WannaCry RE + Ransomware Lab

Reverse-engineered WannaCry with Remnux and identified the kill-switch. Wrote a basic Python ransomware to study lifecycle internals, in a Windows + Ubuntu malware lab.

Columbia research2021 - 22

US States Debt Structures

Database build for Prof. Oliver Giesecke (Columbia) - extracted maturity-structure data from US-state financial reports. Pandas/NumPy + AWS pipeline.

ML · IME6722022

Loan Default Classification

Predictive ML pipeline on a ~200k-row loan dataset - Random Forest, AdaBoost, Logistic Regression, and ANN benchmarked side by side with full EDA.

Unity · C#2021

The Lost Prince + Haunted 3D

Unity 2D & 3D games with the IITK Gamedev Society - C# for enemy AI, movement, scene transitions, health systems, plus ShaderLab work on the 3D horror experiment.

Play Store · published2021

Noted, TicTacToe & Number Magic

Three cross-platform apps published on Google Play. Noted is a Flutter + Node + MongoDB note app; the others are mobile-first games with clean state management.

Award
Google Code Jam 2021
Global rank 794 of 37,000+
Award
Google Kick Start 2021
Best rank 1,544 · 19,000+ globally
Published
3 apps on Play Store
Noted · TicTacToe · Number Magic
Writing

Notes from the field.

Occasional writing on systems quirks, model behaviour, and learning curves.

All posts on Medium
Stack

Tools I reach for.

AI / LLM systems
Agent orchestrationLLM routing · 400+RAG / Vector DBPrompt engineeringOpenAI · AnthropicGemini · FathomASR / SpeechEvals · DeepSearchQAMCP
Languages
PythonTypeScriptJavaScriptC / C++DartJavaC#SQLBash
Backend
Django / DRFFastAPI / FlaskNode / ExpressWebSockets · 10kCelery / QueuesREST + GraphQLMicroservicesWebhooks
Frontend
ReactNext.jsReact NativeFlutterTailwindRedux / ZustandD3.jsChart.js
Infra / DevOps
AWSGCPAzureDockerNginx / PM2Blue–greenCI/CDLinux
Data, observability & more
PostgresMongoDBRedisFirebasePandas / NumPyDatadogSentryStripe · RazorpayVAPT · OWASPUnity · C#
Get in touch

Building AI products at Bolto. Always up for a good problem.

If you're working on agent platforms, applied AI, real-time consumer products, or hard infra problems and want to compare notes - reach out. Allergic to architecture astronautics; biased toward shipping.

Current
Bolto (YC S23)
Previously
Spine AI · Sigiq.AI
Degree
B.Tech · IIT Kanpur '24
Location
Remote · India