For concurrency bugs that should be impossible, not just rare
Hire Kotlin Developers
Kotlin's null-safety and structured concurrency only protect a codebase that actually uses them with discipline. A platform type or a leaked coroutine slips through the exact gap the language exists to close, and these engineers are tested on catching it.
- Profiles typically within two business days
- Replacement Assurance: If an engineer is not the right fit, a replacement from our own team starts within ten business days of your request, at no extra cost
- You interview before placement if you want to
- At least four hours a day inside your core working hours. Two hours plus a daily written handover for the US West Coast
- 14-Day Risk-Free Trial: For your first engineer on a time-and-materials engagement. Up to 14 calendar days or 80 logged working hours, whichever comes first. End within the trial and pay nothing for trial hours. Continue beyond it and those hours are billed at the agreed rate. Unpaid trial work remains ours if you stop
How we evaluate a Kotlin engineer
The tasks, the signals and the onboarding, walked through by the people who run them.
90 secSample frame · video pending01Published, not promised
The assessment behind every engineer we send.
The Kotlin bar is published, not assumed: five competencies, the exact task behind each, and the shortcut that ends a candidacy. Most interviews ask about syntax sugar. This one asks whether the concurrency is actually safe.
What we listen forWhether they understand coroutine scope and cancellation, not just the async keyword equivalent.
A coroutine launched from a screen keeps a network call running long after the screen has closed. Diagnose why and fix it.
- What strong sounds like
- Identifies the missing structured scope tied to the screen's lifecycle and proposes a fix that cancels automatically, not manually.
- What gives us pause
- Adds a manual cancellation call at screen exit instead of fixing the coroutine's scope in the first place.
Kotlin · Coroutines · Kotlin Multiplatform
Ktor · Compose Multiplatform · Spring
Kotest · JUnit · MockK
Gradle · IntelliJ · Detekt
02Who you actually meet
The bench, priced by seniority.
Three seniority tiers, priced honestly, and the engineers who fill each one today. Real names and photos take their place as soon as we can share them, and the standard stays exactly the same.
Engineer
Features scoped tightly enough to ship inside your review bar, every time.
The right first hire when your seniors already set the standard.
$2,500–3,200per month
Senior
The hard module nobody else wants to own, taken end to end.
Ownership of a surface, without adding a manager to your headcount.
$3,500–4,400per month
Lead
The workstream's decisions, made daily, so nothing waits on a meeting.
One accountable voice for a pod or initiative that can't afford to drift.
$4,700–5,900per month
Kotlin engineer
3 yrs · US East overlap
Fixed a coroutine leak that kept network calls alive long after screens had closed
- Kotlin
- Coroutines
- Kotest
Senior Kotlin engineer
7 yrs · UK + EU hours
Redesigned a contradictory UI-state model into a sealed class hierarchy that made the bug class disappear
- Kotlin
- Ktor
- MockK
- Multiplatform
Lead Kotlin engineer
10 yrs · EU + US split
Owns the shared Kotlin Multiplatform module two mobile teams now build on
- Kotlin Multiplatform
- Architecture
- Compose Multiplatform
- CI/CD
Indicative ranges, representative profiles. Exact figures and named engineers arrive with your shortlist.
Weighing this against a freelancer, a direct hire or a marketplace? See the honest comparison
03From stated problem to first change
Four steps, each closing on evidence.
The hiring sequence favours evidence over a features checklist. Every step produces an artefact you can inspect, and exiting after any of them costs nothing.
Define the safety problem
We map where your codebase's concurrency or null-safety guarantees are actually under strain. The brief names that problem, not a list of Kotlin keywords.
A brief your leads signMatch against your codebase
Candidates are screened against your actual coroutine patterns, your Java interop surface and your review culture. Three engineers who read your code beat thirty who list Kotlin on a CV.
Three fits, not thirty CVsAssess on the real tasks
Bring your own engineers to the coroutine-leak and sealed-class exercises. Concurrency judgement is visible here, not a rehearsed answer about syntax.
Evaluation you can watchOnboard inside your process
Access, standards and a first bounded fix merged for real. Continuity cover means a departure is handled on our side before your roadmap notices.
A merged change in week one
04Evidence and proof
Engineers who made concurrency actually safe.
Kotlin proof is a leak or a race condition caught before it reaches users, not a clean build alone. Every record here waits for written client approval before production.
Explore case studies
A coroutine leak found before it drained a fleet of devices.
Tern's sync feature quietly kept coroutines alive after screens closed, a slow battery drain nobody had traced. An embedded Kotlin engineer found the leak and fixed the cancellation handling before the next release.
- Battery drain reports
- Eliminated
- Time to root cause
- Under one week
He found a platform-type crash our static analysis had missed for two release cycles.
Sample · pending client approval
Our sealed-class redesign made a bug class that used to recur every quarter simply stop happening.
Sample · pending client approval
05Three shapes, one standard
Add an engineer, a platform pod, or a practice.
Most engagements start small: one engineer working inside your existing coroutine-heavy codebase. Larger needs call for a pod that owns a shared module across your Android and backend targets. A platform genuinely delivered, rather than a seat filled, is a job for the practice instead.
- Team extension
One named engineer
A single Kotlin specialist inside your direction and your reviews. The smallest commitment, and the most common starting point.
- Delivery pods
A platform pod
A pod with its own lead that owns a Kotlin Multiplatform module shared across your apps. You set priorities while the pod carries delivery.
- Mobile app development
The practice, not the person
When the honest need is a mobile platform built end to end, not a role filled, mobile app development takes on that responsibility instead.
06Straight answers
Asked before a Kotlin hire is signed.
01What does a Kotlin engineer actually do day to day?
Writes structured, cancellation-safe coroutines, closes the gaps Java interop reopens in null-safety, and models state with sealed classes instead of loose booleans and flags. The unglamorous majority of the work is discipline the compiler cannot enforce alone.
02Do you hire for Kotlin on Android specifically, or more broadly?
Matched to where your code actually runs. Concurrency and type-safety judgement transfers across Android, backend and multiplatform work, then the evaluation confirms familiarity with your specific runtime.
03Can we run our own interviews as well?
Yes, the published tasks are built to be reused directly. Some clients now run the coroutine-leak exercise themselves in later hiring rounds.
04How fast can a Kotlin engineer start?
A shortlist arrives within days from a continuously evaluated bench. From there, start speed mostly tracks how quickly your side can grant repository access.
05Who manages the engineer day to day?
Your leads set direction and hold the review bar, same as with any hire. We take on what sits behind that instead: continuity, payroll, replacement exposure and the transitions in between.
06What if the engineer is not the right fit?
Tell us as soon as you notice and the swap is funded by us. The next engineer arrives briefed on precisely what missed, so a repeat mismatch is unlikely.
07Do your Kotlin developers use AI coding tools?
Yes, openly. AI drafts boilerplate and test fixtures quickly; the engineer stays accountable for every concurrency decision, null-safety boundary and merge that reaches your codebase.
08How does pricing work for a hired Kotlin engineer?
The bands above frame the honest range; your shortlist arrives with the exact number attached. Monthly billing, no fee before an interview, and notice-period exit only.