Sarthak Kalpasi

Software Engineer

I build backend systems and self-hosted infrastructure, focusing on Linux systems, networking, and low-level performance.

Interests: Cycling, Mountaineering, Urbanism, Linguistics, and Reading.

Currently building: Wortel, a closed-loop language learning ecosystem for active recall and production.

Writing

Jun 2026 A Multi-Node k3s Cluster, Load Tested to Saturation Mar 2026 Hiding Downtime Behind a Proxy Mar 2025 Self-Hosting on a Raspberry Pi Feb 2024 Firewalls and NAT on Linux Oct 2023 Encrypting Files and Connections Aug 2023 An IPsec VPN with LibreSwan Apr 2022 A Reverse Shell from an Online Compiler

Projects

JustTalk P2P secure voice/text protocol in Rust & Electron

BitChess Chess engine in C using bitboards & alpha-beta

Userland ACLs Linux access control using extended attributes in C

Encrypted File Copy File encryption utility using OpenSSL & HMAC in C

Authenticated IRC Secure IRC protocol with Needham-Schroeder handshake in C