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About

Sidharth Singh

Software Engineer at 1buy.ai · Delhi, India

I am a backend engineer with a little over two years of production experience. I have spent that time inside procurement, logistics and supply-chain platforms, where the interesting problems are throughput, correctness under concurrency, and keeping many services in agreement about what just happened.

At 1buy.ai I work on an ultra-small team that owns core platform flows end to end. That has meant MongoDB aggregation pipelines over 100M+ pricing documents, a Rust job scheduler built on Tokio and semaphore-bounded worker pools, shared pricing logic compiled from Rust to WebAssembly, and an order-fulfilment backend on FastAPI, PostgreSQL and Kafka.

Before that I was at RapidShyp, a B2B shipping platform for marketplace and multi-channel sellers, building Rust (Actix Web) microservices, Kafka pipelines and carrier integrations for bulk order processing and order lifecycle orchestration, with MongoDB, MySQL, Redis, TiKV and etcd in the mix.

Outside work I like to go one layer deeper than the job requires: PostgreSQL query planners, async runtimes, HNSW vector indexing, and the ways distributed systems fail. This site is where I keep that learning honest and in public.

Expertise

What I know, and how well

An honest self-rating rather than a wall of logos. Four levels, from tools I use daily to things I am actively learning.

  • Daily driver
  • Shipped in production
  • Working knowledge
  • Actively learning

Languages

Rust and TypeScript for most of what I ship; Python when the data layer calls for it.

  • Rust

    Actix Web, Tokio, serde, rdkafka, wasm-bindgen

    Daily driver
    • Async services on Tokio and Actix Web: Arc<Semaphore>-bounded worker pools, backpressure through bounded channels, atomic job claims and cancellation-safe tasks.
    • Let the type system carry the invariants: serde-typed domain models, Result-based error handling, Send + Sync discipline for multi-instance safety.
    • Rust as the single source of truth: shared crates compiled natively for services and to WebAssembly for TypeScript, with parity tests on both sides.

  • TypeScript

    NestJS, Node, React

    Daily driver

  • Python

    FastAPI, SQLAlchemy 2 async, asyncpg

    Shipped in production

  • Java

    Spring Boot

    Shipped in production

  • SQL

    Shipped in production

  • Go

    Working knowledge

Backend & architecture

Event-driven services with clean boundaries, built to survive more than one instance.

  • Actix Web

    Daily driver

  • NestJS

    Daily driver

  • Hexagonal architecture

    Daily driver

  • Event-driven design

    Daily driver

  • FastAPI

    Shipped in production

  • Concurrency & async runtimes

    Tokio, semaphore-bounded worker pools

    Shipped in production

  • Spring Boot

    Working knowledge

Data & messaging

MongoDB at 100M+ documents, Kafka for everything asynchronous, and Postgres as the current deep dive.

  • MongoDB

    Aggregation pipelines, compound indexes, Decimal128

    Daily driver

  • Apache Kafka

    Plus a self-directed deep dive in Rust

    Shipped in production

  • Redis

    Shipped in production

  • MySQL

    Shipped in production

  • PostgreSQL

    Daily driver at work; internals deep dive in progress

    Shipped in production
    • In production every day: schema design, SQLAlchemy 2 async with Alembic migrations, pgvector similarity search, append-only event tables.
    • Fluent at the usage layer: query design, EXPLAIN ANALYZE, compound and partial indexes, lock-aware DDL on hot tables.
    • Going below the surface: an eight-week internals course on the planner, storage layout, MVCC, WAL and buffer management, tracked on the progress page.

  • etcd / TiKV

    Working knowledge

Infra & cloud

Comfortable shipping containers; levelling up on provisioning infrastructure from scratch.

  • Docker

    Shipped in production

  • Linux

    Shipped in production

  • CI/CD

    Shipped in production

  • AWS

    EC2, S3, Lambda; SAA-C03 on the roadmap

    Working knowledge

  • Kubernetes

    Actively learning

  • Terraform

    Actively learning

AI & search

LLMs as components inside real workflows, not demos.

  • LLM integration (Claude)

    RFQ and trade-document parsing

    Shipped in production

  • RAG pipelines

    Working knowledge

  • Vector search

    Atlas Vector Search, pgvector

    Working knowledge

  • HNSW indexing

    Actively learning

Frontend

Enough to ship the internal tools the backend needs.

  • React

    Shipped in production

  • Next.js

    Shipped in production

Career

Where I have worked

Two companies, three roles, all of them on the backend of platforms that move physical goods.

Full resume

  1. Mar 2026 – Present · Okhla, Delhi

    Software Engineer at 1buy.ai

    AI-powered B2B electronic component intelligence, sourcing and procurement platform.

    • Building the order-fulfilment backend in Python (FastAPI), PostgreSQL and Kafka: purchase order to shipment to customs workflows with DHL carrier API integration, AI parsing of trade documents (packing lists, Bills of Entry) via Claude, and event-driven cross-department messaging.
    • Designed the inbound-mail pipeline: cheapest-first anchoring of every email to its order or shipment, a two-stage classify-then-act flow over a plug-in registry of 16 LLM handlers, per-step model routing, and dispatch through a transactional outbox, with deterministic no-network tests.
    • Python
    • FastAPI
    • PostgreSQL
    • Kafka
    • TypeScript
    • NestJS
    • MongoDB
    • Rust
    • Tokio
    • WebAssembly
    • Claude API

  2. Apr 2025 – Feb 2026 · Gurugram

    Software Engineer at RapidShyp

    B2B logistics and shipping platform.

    • Engineered core backend microservices in Rust (Actix Web on the Tokio runtime) and Java: async handlers, serde-typed domain models and backpressure-aware worker pools, improving API concurrency and throughput while reducing latency under peak shipping loads.
    • Built event-driven pipelines on Apache Kafka for real-time order processing, shipment status synchronisation and multi-seller fulfilment across marketplace and storefront sales channels.
    • Rust
    • Actix Web
    • Java
    • Kafka
    • MongoDB
    • MySQL
    • Redis
    • TiKV
    • etcd

  3. Jul 2024 – Mar 2025 · Gurugram

    Associate Software Engineer at RapidShyp

    • Designed and owned the B2B Bulk Orders and Purchase Requisition flows in the Order Management System: bulk upload and validation, multi-seller shipment creation, approval workflows and order orchestration at scale.
    • Brought marketplace and multi-channel seller orders into one fulfilment pipeline, so every sales channel flows through the same order lifecycle and logistics integrations.
    • Rust
    • Java
    • React
    • Next.js
    • MongoDB
    • MySQL
    • Docker

  4. Sept 2020 – Jun 2024 · Education

    B.Tech, Computer Science & Engineering (Bioinformatics)

    Vellore Institute of Technology (VIT), Vellore · CGPA 8.22 / 10

Beyond work

Learning in public

A resume is a snapshot. These two pages are the moving picture.

RoadmapFuture projects and visions, each with a status and a timeframe, never an exact date.ProgressLearning journeys with honest percentages, milestones and a dated log.