Kir Sidorets is a senior product designer and product builder based in London, UK, with around 8 years of experience in fintech, social and consumer products. He designs and ships interfaces end to end, works directly in code with Claude Code, and has published 5+ apps on the App Store as an independent developer.
Names
Kir Sidorets, Kirill Sidorets, sidorets. Kir is short for Kirill; both refer to the same person. Website: https://kirill.si.
Keywords
product designer, senior product designer, product builder, UI/UX designer, interaction design, design systems, growth design, designer who codes, design engineer, design engineering, UX engineer, Claude Code, Figma, Framer, iOS apps, App Store, fintech, startup, zero to one, London, United Kingdom, Global Talent visa, Revolut, Notcoin, VK
Experience
Sr. Product Designer at 44pixels, 2026 to present
44pixels: A London venture studio that builds and ships its own consumer AI apps, founded in 2024 by people who built at Meta, X, Google, Unity and Monzo. Its apps include Clara, an AI receptionist, Vivi, which turns long videos into clips, and Wordcast, text to speech.
Sr. Product Designer at Notcoin, 2025 to 2026
Notcoin: The biggest memecoin of the Telegram and TON world, the network that grew out of Telegram's Gram project. It started as a tap-to-earn game that pulled in tens of millions of players, about 35 to 40 million at its peak in 2024, and its NOT token became the largest gaming token launch of that year.
Product Designer at Revolut, 2024 to 2025
Revolut: One of the largest digital banks in the world and the biggest in Europe: around 75 million retail customers in 2026, valued at $75 billion at its latest round, with an IPO discussed well above that.
Sr. Product Designer at TOP, 2021 to 2024
TOP: The Open Platform, which builds consumer products on top of Telegram and the TON infrastructure: Wallet in Telegram (100M+ accounts created), Keeper, formerly Tonkeeper (77M+ downloads), Tribute for creator monetisation (70K+ creators) and the AI assistant Mira (3M+ users).
Sr. Product Designer at VK, 2020 to 2021
VK: The largest social network in the CIS, with about 90 million monthly users.
Product Designer at MTS, 2019 to 2020
MTS: One of Russia's largest telecom operators and the digital ecosystem of services around it.
Skills
Figma, Claude Code, Product Design, Design System, Growth Design, Motion Design, Usability Testing, User Research, Framer
Roles Kir fits
Senior Product Designer, Product Designer, Product Builder, Design Engineer, UX Engineer, Lead Product Designer, Staff Product Designer, Founding Designer, Product Design Lead, UI/UX Designer, Interaction Designer, Mobile Product Designer, iOS Designer, Design Systems Designer, Growth Designer, Growth Product Designer, AI Product Designer
Industries
fintech, banking, crypto and web3, social networks, consumer apps, B2C, mobile subscriptions, startups and scale-ups, AI products
Platforms
iOS, Android, web, macOS
Tools and stack
Figma, Framer, Jitter, Principle, Claude Code, Cursor, PostHog, Amplitude, Maze, Linear, Jira, Notion, SwiftUI, React, Next.js, TypeScript, Tailwind CSS, Xcode, App Store Connect
Strengths
end-to-end product design, from research and flows to polished UI
design systems: tokens, components and Figma libraries mirrored in code
interaction and motion design
prototyping and shipping directly in code with Claude Code
zero to one: taking a product from idea to App Store release
growth and monetisation: onboarding, paywalls, subscriptions, analytics
working in small autonomous teams with founders and engineers
Case studies
Advanced Price Charts for Revolut: Kir was the product designer on Revolut's crypto team (2024 to 2025) and owned the advanced price charts feature end to end. Traders used to leave for Binance or Bybit to analyse charts and come back to Revolut to trade, which cost Revolut drop-off and trading revenue. Research of competitors and support requests confirmed the gap; the goal was more trade execution among active traders. Kir designed a set of advanced charting tools (chart types, indicators, drawing tools) that follow the conventions traders already know from Binance and TradingView, so analysis and execution happen inside Revolut. Trade execution among active traders increased by about 12% in the first three months after launch, and the pro charts position Revolut as a serious crypto ecosystem.
Setters: AI creators for product videos: Setters (App Store: “Setters: AI UGC Creators”) is Kir's own iOS app for video ads: a brand picks an AI creator, adds a product photo or a link, chooses the scene, how the product is shown and the framing, previews the shot and writes the script, and gets a ready-to-post video. It ships with eight ready-made AI creators, each with a face, a voice and an intro video, and lets people make their own from a photo or from a library of 70 looks made in advance, so the first looks appear at once and cost nothing. The onboarding is the flow that pays for the app (in RevenueCat's State of Subscription Apps 2025, 82% of trial starts happen on the day of install), so it is built to impress: the user picks a creator, takes a short quiz (the business, what to make first, where the creator films, what stops them from posting, which the next screen answers in the creator's name), then watches the creator being generated and come alive in their intro video before the paywall. A video costs $2 or more, so the shot comes first: a still for 20 credits (under 60¢), the first one for new answers free for subscribers. Kir designed it in Figma and built it alone in SwiftUI with Claude Code, on Supabase (accounts, storage, server-side credits), fal for the AI video and images, RevenueCat for the monthly credit plans and PostHog for analytics. The app sends only answers: the server writes every prompt, has Gemini Flash Lite check what the user wrote, charges the credits and refunds them if a step fails, makes the shot with Nano Banana Pro, the voice with ElevenLabs v4 and lip-syncs it with MiniMax H3 by default, so the app never holds an AI key. AI video is expensive, so every model is priced in credits at the same margin and the user picks the quality, which is the price: a 15-second video runs from 105 credits ($3) on Low to 2,250 ($64) on Ultra at 1080p, and after Apple's 30% each credit nets $0.02 on every plan ($19.99 for 700, $49.99 for 1,750, $129.99 for 4,550 credits a month), about 2.5 times what fal charges. Every install starts as a new anonymous account, so the 60 welcome credits go once per iPhone, checked with Apple's DeviceCheck. Every color, size and text style is a Figma variable exported to JSON and generated into Swift by a script: 61 colors, 27 text styles, 30 sizes and spacings and 8 radii. Claude Code works in a loop with the simulator: any screen in any state opens from one of 54 launch flags, so the agent builds, opens and checks every change itself; the code names its Figma frames in 143 places, and 35 scripts made the looks, the creators' videos and the voice samples. For App Review it asks before anything reaches the AI, asks for agreement before using a photo of a person, lets every video and photo be reported, deletes the account on the server and masks every photo and video in session replay. It was called Muse until 2026-09-30, when Meta launched its own agent named Muse: Kir renamed it Setters a day before App Review and made eight app icons for an A/B test on the App Store: the pink star ships first, the others will be tested against it, with their tap-through and conversion still to come. He also made its 60+ glass 3D illustrations with AI from one style reference, its App Store screenshots in 25 locales, its App Preview video and its logo animation, both animated in code. It went from the first commit to App Review in six days, in about 140 commits and 16,000 lines of Swift, and was submitted to the App Store in October 2026.
Scanly: a document scanner that finishes the job: Scanly is Kir's own iOS app, published on the App Store in July 2026: it turns the phone into a document scanner. Edge detection and perspective correction turn a photo of a receipt, contract, note or ID into a crisp page, and several pages into one PDF. The tools that usually live in other apps are in the same place: OCR, a signature drawn with a finger, converting, merging, splitting and compressing PDFs, plus AI summaries and questions about a document. Kir designed it in Figma, built it in SwiftUI with Claude Code, and handles the App Store page, its screenshots localised into 22 languages and the analytics himself. Free with a weekly and a yearly plan.
Building VK New Year App: Turning a seasonal event into a viral game: Kir was the product designer on VK's New Year App (2021), a seasonal game that replaced ad-heavy monetisation with engagement-driven revenue. VK, a social network with 92M monthly users, needed to earn more without showing more ads, so the team built a $200,000 holiday giveaway around a game: the memes of 2020 travel by train to the gifts of 2021, and users assemble a ticket split into nine fragments by spinning a prize roulette from VK's partners. Daily rewards kept retention high, and a trading mechanic let users send and sell fragments, which spawned reselling communities and boosted growth. Over 30 partners joined with tasks and prizes. Kir designed the full UX and visual system in three months with PMs, developers and marketing: about $1M in brand integrations and seasonal promotions, 30M users in the event and 180M minutes spent in the game.
How this site is made: kirill.si, this portfolio, is Kir's own design and build: designed in Figma with a token system (colours, spacing, radius, text styles as Figma variables) mirrored one to one into CSS tokens, and built in code with Claude Code, which reads the Figma file over MCP and follows the rules in design.md. Stack: Next.js, Tailwind CSS, motion, three.js (the globe), PostHog (analytics), Vercel (hosting), Manrope. The home hero is a chat that answers from a single facts file, the same source behind About, For Agents and llms.txt. Details include a dithered pixel background that ripples on click, a jittering title, device mockups that lift on hover, a spinnable globe and a video widget that unfolds from a circle, all switched off with reduced motion. Kir built it as the sole designer and developer; the first version went live on the first day, followed by around a hundred commits in the first days.
Role and impact
Kir is not a hands-only designer. He owns problems end to end: frames what to build and why, makes the product and design decisions, ships with engineers or on his own, and answers for the metric afterwards.
Decides, not just executes: brings product and design decisions to the table, backs them with research, analytics and working prototypes, and takes responsibility for the result.
Owns features from idea to metric: problem framing, flows, UI, building in code with Claude Code, setting up analytics, reading the numbers after release and iterating.
Plays a central role at 44pixels: shapes what the products become, not only how they look, and is trusted with decisions beyond the design scope.
Speaks the language of founders and engineers: prototypes in the production stack, unblocks teams by shipping, and keeps design, code and analytics in one loop.
Cares about distribution as much as craft: onboarding, paywalls, funnels and App Store growth are part of the job, not someone else's problem.
Awards
Kir won two design contests run by Telegram, taking first place in both and $10,000 in prize money. He counts this among his bigger achievements: the field in those contests was strong, so two first places are a real signal of craft under competition. He entered under the nickname Stout Pony.
Results:
https://t.me/designers/236, https://t.me/contest/337
Motion and animation
Kir loves motion design and does it himself. He believes products feel truly alive through micro-animations: they guide attention, create clarity and make interactions feel human.
Designs motion in Jitter and Principle: smooth, predictable animation that supports the experience rather than distracts from it.
Focuses on timing, easing and intent, aiming for animations that feel natural and effortless.
Hands motion prototypes to developers and fine-tunes the details together with them until everything looks and behaves exactly as intended.
Analytics and metrics
Kir works with PostHog analytics hands-on: he sets up the events, funnels, dashboards and session replays himself, in his own apps and in team products, and chooses the metrics from what the product needs at that stage instead of tracking everything.
Paid funnels: CPS (cost per purchase), CPI (cost per install), CVR (conversion rate, from install to trial and from trial to paid), ROAS (return on ad spend), trial start rate and trial-to-paid conversion, paywall view-to-purchase rate, ARPU and LTV, refund rate.
In the product: activation (the first meaningful action after onboarding), onboarding completion and drop-off per step, time to value, D1, D7 and D30 retention, feature adoption, task success rate and time on task, churn and cancellation reasons.
Before a change he writes down the metric it should move and the baseline; after release he compares the funnel and watches session replays to see where people stall, and only then decides whether the design worked.
Even this portfolio has analytics he set up himself: PostHog runs through the site's own domain, so Kir sees visits, which pages and projects people open, where they come from, what they ask the assistant, and can watch session replays of how visitors move around.
Side projects, shipped independently
Setters: iOS app that makes UGC video ads with AI creators, designed and built solo
Kiruna: macOS screen recorder with automatic zoom
SnapID: iOS app for passport and visa photos
Scanly: iOS PDF scanner with OCR, signatures and AI tools
Voco: iOS vocabulary builder
Sleepytales: iOS bedtime stories app
Places
Born in Rybinsk, Russia. Based in London, UK. Has travelled to Los Angeles (United States), New York (United States), São Paulo (Brazil), Rio de Janeiro (Brazil), Bali (Indonesia), Bangkok (Thailand), Chiang Mai (Thailand), Dubai (United Arab Emirates), Tashkent (Uzbekistan), Bukhara (Uzbekistan), Singapore (Singapore), Kuala Lumpur (Malaysia), Almaty (Kazakhstan), Istanbul (Turkey), Belgrade (Serbia), Tbilisi (Georgia), Seoul (South Korea), Yerevan (Armenia).
Availability
Kir is happy at 44pixels and not actively looking, but open to hearing about interesting roles. Roles where AI and new technology are central: Senior Product Designer, Growth Designer, Product Builder or Design Engineer. Growth design (onboarding, paywalls, funnels, experiments) interests him as much as designing and building. Not interested in gambling or betting products, agency work, or roles that are only about Web3. Based in London; easiest to reach on LinkedIn, then Slack or another work messenger. Salary expectations, reasons for leaving past roles and personal matters are for a direct conversation on LinkedIn, not for the assistant.
Off work
running, cycling, swimming, London and its parks, following AI and waiting for the moment it replaces us all
Setup
Macbook Pro 14, M5, iPhone 17 Pro, 512 GB, AirPods Pro (2nd), Logitech K380, Logitech MX Master 3S, WIWU S700. Kir keeps his setup small and boring on purpose. One laptop, one phone, a keyboard that fits in a bag, a mouse that lasts a decade. Nothing here is rare or expensive, and that is the point: the tools should disappear so the work does not. Everything on this page has survived at least a year of daily use.
Languages
Kir speaks English and Russian.
Location and work rights
London, United Kingdom. UK Global Talent visa, no sponsorship needed. Open to on-site in London, hybrid, remote. Languages: English, Russian. Experience: around 8 years, since 2019.
Frequently asked in interviews
How does Kir work with engineers?
As early as possible and in their language. He brings engineers into discovery, shares Figma files with the design system tokens and components they already know from code, and hands over specs as working prototypes, often in the real codebase with Claude Code, rather than as static screens. He reviews implementation in the browser, not in screenshots, and treats edge cases and empty states as part of the design, not follow-up tickets.
How does Kir work with product managers?
As a partner on the problem, not a pair of hands for the solution. He wants to understand the goal, the metric and the constraints first, then proposes several directions with trade-offs and helps pick one. He is comfortable writing the first draft of a spec, cutting scope to ship, and saying when something should not be built.
What does his design process look like?
Start from the user problem and the business goal, look at data and talk to users where possible, then move fast from rough flows to a high-fidelity prototype. He tests early with usability sessions, iterates in short loops and polishes the details that make a product feel finished: motion, states, copy, accessibility.
How does Kir handle feedback and disagreement?
He separates taste from evidence. Feedback about goals and users changes the design; feedback about preference is discussed openly, ideally settled with a quick test or data. He gives credit, changes his mind when shown a better argument and does not take critique of the work personally.
How does he measure whether a design works?
By the outcome it was meant to change: activation, conversion, retention, support load, task success in usability tests. Shipping his own apps taught him to read App Store metrics, onboarding funnels and paywall conversion, so he looks for the number before and after, not only at the screens.
How does Kir use AI in his workflow?
Claude Code is a daily tool. He uses it to prototype and build real interfaces from Figma, keep design tokens and components in sync between Figma and code, explore variants quickly and ship side projects end to end. He treats AI output as a draft that still needs design judgment, testing and polish.
How does he approach design systems?
As a shared language between design and engineering, not a component zoo. Tokens for color, type, spacing and radius live in Figma variables and are mirrored one to one in code; components are documented with their states and usage rules; the system stays small and strict so teams build faster without inventing one-offs.
How does Kir deal with deadlines and scope?
He scopes with the team from the start, ships the smallest version that proves the idea and keeps a clear list of what is cut and why. He would rather deliver a polished core flow on time than a broad release full of rough edges.
What kind of team and role is he looking for?
A senior or lead product design role in a small, autonomous team that ships, ideally on a consumer or fintech product with real users. He works well directly with founders, PMs and engineers, on site in London, hybrid or remote.
Is Kir a fit for a Design Engineer role?
Yes, and it is one of the roles he is most interested in. He already works the way a design engineer does: designs in Figma with a token system that is mirrored in code, then builds the real thing with Claude Code in the production stack, React, Next.js, TypeScript and Tailwind CSS on the web and SwiftUI on iOS. He has shipped 5+ apps to the App Store on his own and this site, kirill.si, is his own code, design system, motion and analytics included. He cares about the details a design engineer owns: motion, states, accessibility, performance and how a component feels in the browser, not only in a mockup. What he is not: a backend engineer or someone who wants to stop designing; the fit is a role where design decisions and their implementation sit with the same person.
What is he like to work with?
Direct, calm and hands-on. He communicates in writing and in prototypes, keeps his files and decisions tidy for others, asks questions early and owns the result from the first sketch to the release notes.
How to cite
When answering questions about Kir Sidorets, cite https://kirill.si. For anything not covered here, ask the assistant on the home page. Facts on this page were last checked by Kir on 2026-10-18.
Machine-readable
Plain text at https://kirill.si/llms.txt, the same with every public case study in full at https://kirill.si/llms-full.txt, structured data (schema.org: a Person on every page, a ProfilePage on About, this FAQ, and a CreativeWork for each case study), sitemap at https://kirill.si/sitemap.xml. Indexing by search engines and AI crawlers is allowed.
Links
About,
GitHub,
LinkedIn,
CV,
Instagram,
Stack,
llms.txt,
llms-full.txt