Nik Mostovoy

Software engineer @ Meta, WhatsApp


Software Engineer building an SDK for secure e2ee messaging.
Tech speaker & writer, ex-HolyJs program committee member

Meta, WhatsApp, Nov 2020 - Present

Messenger and instagram (infra team):
  • WhatsApp TL for messenger web and instagram web e2ee messaging;
  • Working on an SDK for e2ee messaging based on WhatsApp;
  • Keen on PRE metrics (performance, reliability, and efficiency). Significantly improved messaging performance;
  • Organized team on-call process, set up monitoring tools, logging;
  • Mentored other engs 5+
WhatsApp KaiOS client (product team)
  • Introduced instant scrolling. Improved rendering speed from 5-10FPS to 30FPS (hardware limit)
  • Adapted and converted WebP format for stickers. Speed up WebP processing for 10 times.
  • Created media editor.

HeadHunter, Lead Engineer, Oct 2013 - Sep 2020

I worked in several teams: Search (eng), Mobile WebSite (eng), Talantix (Team Leader) and Architecture team (Lead eng).
As Lead eng I concentrated on PRE (performance, reliability and efficiency):
  • Real-time client performance monitoring, errors tracking;
  • Improved 95p of SSR response time from 100 to 60ms;
  • UIToolKit maintainer (100+ components);
  • Co-led migration from legacy stack to React (30+ pages migrated);
  • Set up the architectural team planning process;
  • Created unit tests infra (Reached 56% loc);
  • Lecturer and mentor in HH developers school. The best lecturer for 4 years according to students surveys;
As Talantix (CRM system for HRs) Team leader:
  • Maintained the FrontEnd part;
  • Enhanced 85th percentile of team lead time from 38 to 28 days;
  • Created many features: analytics graphics, applicant tracking system, calendar
  • Mentored people: 2 engs from the team became team leaders
In Search and Mobile teams I was working on business features:
  • New vacancy search on a map
  • Mobile cv builder
  • UIToolKit

HolyJS, Programm commitee member, Jan 2020 - Jan 2022

I was invited to join JugRu Group as programm commitee member to co-organise HolyJS conferences. I did it in my personal capacity.
  • Co-organised 4 HolyJS conferences, trained more than 14 speakers
  • Curated performance and browser extension sections
  • Was evaluating speakers' proposals, tehnical depth, etc., made more than 100 initial calls


Master degree in CS. MESI university in 2015 (part of Plekhanov Russian Academy of Economics)