OleksandrZavazhenko

A feature is not finished when the code compiles.

Senior iOS Engineer/4+ yrs in production/Remote worldwide

Selected work [email protected]GitHub ↗LinkedIn ↗
Portrait of Oleksandr Zavazhenko
Available · Remote worldwide

How I take a feature to production

  1. Business Need
  2. Product Scope
  3. Architecture
  4. Implementation
  5. Verification
  6. Release
  7. Production Insight
Proof

Part of what I've done in four years.

15% → 0%

Crash rate on a live health product. It stayed at zero across releases.

Crashes only → every failure

I introduced structured non-fatal reporting on a large travel platform, so failures that never crash still surface in telemetry.

85%

Automated test coverage on the key flows of a regulated telecom app.

Signing pain → shared tool

Xcode signing kept breaking our pipeline, so we built a CLI that does it. Open source, still in use.

126 → 0

All 126 storyboards moved into code. Merge conflicts went with them.

Mentee → teammate

Two juniors I mentored now work as iOS developers on their own teams.

Shipped → measured

New features went out behind A/B tests. The winning variants raised the app's conversion.

Bug → real incident

In telecom, payments and health a bug is not a bad review in the store. It involves money or regulators. I am used to that level of responsibility.

1 → 10+

I have shipped both ways: alone with everything on me, and inside teams of ten plus.

Business brief → production

Some apps I started from zero, some I maintained long term, and many business features I carried from the first call to release.

Manual builds → one command

CI/CD I have set up more than once and with different stacks: Fastlane, GitHub Actions, signing, tests, TestFlight delivery.

UIKit → SwiftUI

Migrated legacy screens in a large telecom app and fixed the performance and memory issues on the way.

Selected work

Products I helped build and ship.

01 / 08

01 · Travel commerce · multi-market Europe

A new purchase flow for a travel app with millions of downloads.

The consumer app of a European travel operator, live in multiple markets with millions of downloads. The business wanted a new way to sell products inside it. I turned that into technical scope, coordinated product, design, backend and QA, and owned the iOS side through release, with structured non-fatal reporting so failures that never crash still show up in telemetry.

  • Turned the brief into a shippable scope with the product team
  • Owned the module architecture and reviewed every change going in
  • Ran the release and watched production after it
Feature ownershipCross-team deliveryNon-fatal reportingSwift

02 · Energy · EV charging & fleet

The charging app for a 1,300-point EV network, built from zero.

A fuel-and-energy group with one of Poland's largest EV charging networks, over 1,300 public points. I helped build its charging app from zero and a second app for fleet transactions. Chargers go offline, sessions drop, payments hang, and the app has to handle it without lying to the user: charger and connector states in SwiftUI, geolocation and QR scanning, live session state over WebSockets.

  • Designed the charging-session state machine and its recovery paths
  • Built the map, QR and payment flows end to end
  • Extracted the shared Swift package both products depend on
SwiftUIGeolocationWebSocketsSwift PackageGreenfield

03 · Open source · Swift CLI

MQSwiftSign: iOS code signing rebuilt as a Swift CLI.

Signing was the slowest and least reliable part of our pipeline, so we built a replacement from scratch: temporary keychains, certificates, provisioning profiles, export configuration, cleanup, builds and TestFlight delivery. It works as a Swift package or a standalone universal binary for Intel and Apple Silicon, and covers native iOS, Flutter and React Native projects.

  • Co-authored the tool and its signing workflow in Swift
  • Rolled it out across native, Flutter and React Native teams
  • Maintain it in the open: docs, issues, releases
Swift CLICode signingCI/CDFlutterReact NativeView on GitHub ↗

04 · Telecom · self-service, KYC & payments

Self-service for a telecom with 15+ million customers.

The consumer app of one of Poland's largest mobile operators, serving over 15 million customers: account services, offers, and the business-critical KYC, document-upload and payment flows. Every step has to survive a regulator's audit and still be something a user can finish on a phone.

  • Delivered the KYC, document-upload and payment flows
  • Translated legal requirements into concrete screen states
  • Migrated UIKit screens to SwiftUI and fixed performance and memory issues
  • Helped bring automated test coverage on key flows to 85%
SwiftKYC & paymentsCompliance flows

05 · Martech · mobile SDK

An analytics SDK that ships inside other companies' apps.

For a marketing-automation platform used by thousands of businesses, we built the iOS SDK that tracks in-app events and behaviour. SDK work flips the usual rules: your bugs ship inside someone else's app and you cannot hotfix them, so the public API, versioning and backwards compatibility matter as much as the features.

  • Co-built the iOS analytics SDK, from event tracking to app-usage monitoring
  • Kept the public API stable for the apps embedding it
Swift SDKAnalyticsAPI design

06 · Sports tech · BLE hardware · Greek startup

The app behind a smart reaction-training system.

A sports-tech startup makes smart light cells for reaction, coordination and speed training. I worked on the SwiftUI app that drives them: pairing, live telemetry and reconnection over BLE. The signal drops, the device sleeps, and the app has to recover without the user noticing.

  • Wrote the BLE layer: pairing, streaming, reconnect
  • Tested against real devices with the hardware team
  • Collaborated on feature planning and device-interaction reliability
CoreBluetoothTelemetry

07 · Health & wellness · iOS + watchOS

Fixing a 15% crash rate in a breathing app with millions of downloads.

A breathing, meditation and cold-exposure product with millions of downloads, where a crash interrupts something people genuinely rely on. I found and fixed the critical stability issues: the crash rate went from 15% to zero and stayed there across releases.

  • Triaged the crash backlog and fixed the root causes
  • Moved storyboard UI into code: all 126 storyboards, down to zero
  • Set up the Fastlane and GitHub Actions pipeline the team released with
CrashlyticsXCTest

08 · Mentoring · team growth

Two juniors, from zero iOS to their first developer roles.

Two people started with no iOS experience. I mentored both until they were hired into professional iOS roles, and today they ship on their own teams. On the team side I review code, screen candidates and check take-home assignments.

  • Mentored two beginners from zero to hired iOS developers
  • Review code and take-home tasks, help screen candidates
MentoringCode reviewHiring support

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Also shipped
  • release pipelineFastlane and GitHub Actions, from build to TestFlight
  • watchOSthe health product ran on the watch too
  • hybridJavaScript bridges between native and web, in production
  • languagesUkrainian, English and Polish, all working languages
  • side projecta café-discovery site for remote workers cuply.app ↗
  • this sitedesigned, built and deployed it myself

Beyond the code

How I actually work.

I do not start from code. I start from the system: what the feature has to do, where it can fail, what the architecture has to protect. The critical parts I design and write myself. The routine I delegate to tools, then review it like any other code.

  • Feature ownership & releases
  • Architecture & planning
  • Estimates & client calls
  • Code review & mentoring
  • Candidate screening & take-home review

AI-native

AI writes a lot of my code. The judgment stays mine.

  • Claude
  • Codex
  • Cursor
  • MCP
  • reviewed · tested · profiled

Need someone to own a feature end to end?

Open to senior and lead contract roles, remote.

[email protected] ↗Back to top ↑