Senior Mobile SDK Engineer (Swift & Kotlin)

About the role

Typhoon Signal makes an observability SDK for teams whose users are on genuinely bad networks — commuters in Jakarta, users behind aggressive middleboxes, ferry passengers between the outlying islands. Our value is that we report what a real user experienced, which means our SDK has to keep working exactly when everything else does not.

You would own the mobile side of that: the iOS and Android SDKs, the retry and buffering behaviour, the on-device sampling, and the binary size budget that customers absolutely will complain about if we exceed it. Around six hundred engineering teams have our code inside their apps, so a bad release is not something we can quietly roll back.

We are twenty-three people, bootstrapped and profitable, with no sales team and no board. The four-day week is real: Fridays are off, not flexible. The trade is that cash sits a little under what a large company would pay, and we say so in the first conversation rather than the fifth.

What you'll do

• Own the iOS and Android SDKs end to end — API design, implementation, release and deprecation policy.
• Engineer for hostile networks: offline buffering, exponential backoff, delivery guarantees and battery-aware scheduling.
• Hold the line on binary size and startup cost; every kilobyte is somebody else's app launch time.
• Instrument and test against real device fleets, including the low-end Android hardware most of our users are on.
• Write the SDK documentation and sample apps yourself — we have no separate docs team and it shows when we try.
• Support customer engineers directly in our shared channels, because there is nobody else to hand it to.

What we're looking for

• Six or more years in mobile engineering with production ownership on both iOS and Android.
• Strong Swift and Kotlin, plus an understanding of what happens beneath them — threading, memory, app lifecycle.
• Experience building libraries or SDKs consumed by other engineering teams, including versioning and backward compatibility.
• Networking depth: HTTP/2, TLS, connection reuse, and how all of it degrades on a poor mobile link.
• Business-level English; the whole company works in English and this role has no Chinese-language requirement.

Nice to have

• Kotlin Multiplatform or another shared-core approach.
• OpenTelemetry or observability instrumentation work.
• Open-source library maintenance where you had to say no to a feature request in public.

What you get

• Four-day week — 32 hours at full pay, Fridays off
• Profit share paid twice a year
• Remote-friendly across Hong Kong time zones, with the Sheung Wan office open whenever you want it
• 20 days annual leave on top of the four-day week
• Medical insurance and MPF employer top-up to 8%
• Hardware of your choice, replaced when you ask