FS Francisco Sainz

senior software engineer · cto / rust · go · swift · svelte

I build fast, reliable software.

Senior software engineer and CTO shipping things end to end — from Rust engines and Go backends to native SwiftUI apps and SvelteKit on the edge. I care about speed, correctness, and shipping.

Francisco Sainz

Francisco Sainz

senior software engineer

cto · ships end to end

  • 5 shipped projects
  • 4 languages in prod
  • 100% built end to end
  • 0 fluff

selected work

Five things I actually shipped.

Not demos. Real engines, real apps, real users — each one taken from an empty repo to something running.

DiskClean macOS app dashboard showing reclaimable space

DiskClean

Fast macOS disk cleaner

live

Reclaim every byte. A fast macOS disk cleaner with a Rust scanning engine and a native SwiftUI app — it finds dev caches, build artifacts, and forgotten junk, shows every path before it touches anything, and moves files to Trash first. Nothing leaves your machine.

  • Rust
  • SwiftUI
  • UniFFI
  • macOS
700+ GB reclaimable · 0 bytes uploaded
Camera streaming sources and outputs supported by the engine

Instant Streams

Zero-latency camera streaming

open source

Camera streaming that starts the instant you press play. Built on go2rtc, my fork adds keyframe caching, a ring-buffer time-shift, and RTP sequence rewriting so WebRTC playback never waits for the next I-frame — first frame is already there.

  • Go
  • WebRTC
  • RTSP
  • RTP
  • go2rtc
instant first frame · keyframe cache + time-shift

the toolkit

Whatever the problem actually needs.

I pick the tool that fits the job — systems work in Rust and Go, native UI in SwiftUI, product on SvelteKit. The constant is shipping something solid.

  • Rust
  • Go
  • Swift / SwiftUI
  • TypeScript
  • SvelteKit
  • Postgres
  • Cloudflare Workers
  • WebRTC
  • WASM

about

Engineer who likes the whole stack.

I'm Francisco — a senior software engineer and CTO who likes owning a problem from the metal up to the pixels. I care about software that's fast and correct, and about teams that actually ship.

Lately that's meant content-addressed backup engines in Rust, realtime ingestion pipelines in Go, native macOS and iOS apps in Swift, and slick frontends on SvelteKit + Cloudflare. If it's hard and worth doing well, I'm in.


get in touch

Let's talk shop.

Always happy to trade notes on engineering, products, and hard problems. The fastest way to reach me is email or X.

FSFrancisco Sainz senior software engineer · cto / rust · go · swift · svelte · 2026