MADRID, SPAIN · OPEN TO WORK

Prateek Chachra

Senior Software Engineer, React · React Native / Expo · TypeScript · Node.js

Senior engineer with 10+ years in React Native, React and TypeScript. I cut app startup time by 79% (from 608 ms to 127 ms) and built Datadog tracing that pinpoints bugs to the exact line, on apps for enterprise clients including Pfizer and Moderna.

Right now I'm building react-native-audio-effects , a TurboModule bringing real-time DSP and plugin-style controls to React Native's New Architecture, with 17 effects and 7 generators running on AudioKit and Oboe.

I'm also an independent artist, Darzini , releasing music independently, and a speaker at Primavera Pro 2026 on AI and music. Based in Madrid, relocating to Amsterdam; requires visa sponsorship.

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79%

faster cold start

608 ms → 127 ms at AILY Labs

10+

years in production

React Native, React, TypeScript

~2,000

enterprise users

Pfizer and Moderna apps

80%

faster feature work

Design system at Taxfix

Experience

Melboss Music · Madrid

Jul 2026 to Present

Performance Marketing

Ran Meta and Google performance ad campaigns for artists and for Melboss itself, and recommended product changes for SEO and GEO to attract more B2C and B2B clients.
Grew my own artist project (Darzini) to 20k monthly listeners using Spotify and Meta marketing.

Meta AdsGoogle AdsSEOGEO

AILY Labs · Madrid

Dec 2023 to Jun 2026

Senior Software Engineer (Full Stack, React Native)

Cut app startup time from 608 ms to 127 ms (about 79%) through feature-flag caching, state invalidation and a dimension-filter fix.
Part of an 8-person senior mobile core team building 3 React Native apps for enterprise clients including Pfizer and Moderna (~2,000 users), shipping security fixes on a deadline.
Led architectural decisions (GraphQL schema design, SOLID, screaming architecture) for inter-domain communication, and added app-wide caching and failure handling that improved resilience and supported key enterprise sales.
Set up Datadog end to end (tracing, logging, source maps, Session Replay, source code integration) through GitHub Actions, so the team could trace a broken step to the exact line of code.
Fixed a FlashList bug where sticky headers stopped responding to touch events because views were recycled. Shipped an internal patch in a day and raised it with the maintainers, who agreed and fixed it upstream.
Built AI-driven Highcharts visualizations, including prediction sliders, to support end users' decision-making.
Built Claude skills documenting the mobile core's contexts and what each provides (e.g. bookmarks), used by other teams so AI-assisted tasks start with exact context.

React NativeGraphQLTypeScriptDatadogHighcharts

Taxfix · Madrid

Mar 2022 to Aug 2023

Full Stack Engineer

Part of the team that migrated support from Intercom to Zendesk across 4 apps and tens of thousands of users in 4 months, integrating chat and subscription services.
Owned the end-to-end native chat integration with Zendesk using Native Modules.
Bootstrapped and led the Taxfix Support Center in Next.js, with Auth0 authentication and Framer Motion.
Contributed to the Design System by adding new components and tests (Atomic Design, Jest, Storybook), speeding up development by 80%.

React NativeNext.jsNative ModulesStorybookAuth0

Guru.com · Pittsburgh

Apr 2021 to Oct 2021

Senior React Native Engineer

Cut screen load times by 21% via SVG optimization and lazy loading, measured with the React Native Profiler flame graph.
Upgraded Expo 39 to 42 with native module support.

React NativeExpoRN Profiler

Ayu Health · Bangalore

Apr 2020 to Dec 2020

Lead Mobile Engineer

Led 2 developers to launch the AyuMitra iOS and Android app, with Twilio video calling and Firebase real-time messaging.

React NativeTwilioFirebase

Earlier experience · India

2016 to 2020

MyScoot · Nucleus Software

MyScoot (Full Stack, 2019 to 2020): Django/React website plus a mobile app with Firebase notifications and deep linking.
Nucleus Software (Senior Engineer, 2016 to 2018): 3x faster enterprise login via SPNEGO and REST-based SSO.

DjangoReactFirebaseSPNEGO / SSO

Personal projects

Currently buildingv1.0.1 on npm · v2 in development

Real-time audio effects, generators and plugin-style controls for React Native

A native audio library for React Native's New Architecture. Load a sound, build an effect chain, and tweak it while it plays, with controls generated from the same parameter definitions the DSP reads, so a knob can never disagree with the effect behind it.

17 real-time effects: delay, reverb, chorus, flanger, phaser, tremolo, compressor, limiter, noise gate, 4-band parametric EQ, low/high/band-pass filters, gain, pan, distortion and bit crusher, chained in the order you add them.
7 generators: sine, square, saw, triangle and white/pink/brown noise, each with an ADSR envelope, plus a PolySynth that gets chords and unison from a pool of sources rather than a native voice pool.
A control kit built for audio: rotary knobs, taper-aware sliders, XY pads, level meters, a waveform view with scrub-to-seek, an 88-key MIDI keyboard, A/B preset compare, and an effect rack that lays itself out from the schema.
Knob drags run on the UI thread through a Gesture Handler worklet, so a control keeps tracking your finger even while JS is busy decoding a file.
TurboModule on RN 0.88, with Swift and AudioKit on iOS and Kotlin plus Klarinet (Oboe) on Android, working around AudioKit's SPM-only distribution and a Kotlin metadata clash on Android.
Controls ship from a separate entry point, so an app using only the audio API never pulls in Reanimated, Gesture Handler or SVG.

TurboModuleSwift / AudioKitKotlin / OboeC++TypeScriptReanimated

View on GitHub API reference npm

CueSync

Two-sided sync licensing app with an AI music supervisor

View source

A sync licensing marketplace connecting musicians with music supervisors. Musicians keep a catalog with posters, platform links and sync-rights metadata; supervisors post briefs and review submissions anonymously. Built with Expo and Supabase.

Agentic sync search: a supervisor describes a scene and the agent returns a ranked, playable shortlist, running a tool loop over search_catalog, get_track, check_clearance and draft_license_request.
The agent runs server-side in a Supabase Edge Function that rejects non-supervisors, so no model API key ever ships inside the app bundle.
Provider-agnostic model layer (Gemini, Claude, or any OpenAI-compatible endpoint) behind one interface, with a CLI, an eval set and tests sharing a single copy of the agent code with the app.
Anonymous submissions (each musician appears as e.g. Artist 877C), role-locked auth, clearance checks on every pick, and silent blocking so supervisors can stop accepting without signalling it.

React Native (Expo)SupabasePostgreSQLEdge FunctionsTypeScript

Technical skills

MOBILE & FRONTEND

React Native (Expo)Swift / Kotlin (Native Modules)ReactNext.jsTypeScriptRedux Toolkit

BACKEND & DATA

Node.js (Express / Fastify)GraphQLPostgreSQLPython / Django

TOOLING

DatadogGitHub ActionsJestPlaywrightCypressDetoxStorybookDockerGCP

AI TOOLING

ClaudeClaude CodeMCP serversClaude skills

Open source

callstack/react-native-bottom-tabs

Android tab badge colours

doublesymmetry/react-native-track-player

Bug fixes

Writing

20 October 2026·9 min read

Finding samples in plain English, and why the model is the easy part

Splice just shipped an MCP server that lets Claude search their catalog. I was building the same idea into a React Native audio library at the same time, without an API key. The language model turned out to be the least interesting part of it.

All writing

Education & languages

EDUCATION

B.Tech, Electronics & Communications Engineering

Delhi Technological University

2012 to 2016

LANGUAGES

EnglishFluent
SpanishB2
HindiNative

Let's build something

Open to senior and lead engineering roles. The full résumé has the detail, or just send me a note.

Download résumé prateekchachra@live.com