Copy-trading means that a master trader's deals are automatically copied to subscribers' accounts. Imagine: you find a trader with a 30% monthly return. You subscribe, but the signal arrives 10 seconds late — the price has already moved, the trade didn't happen. A mobile app must solve two fundamentally different tasks: for the master — publishing trades and managing subscribers, for the copier — receiving signals, setting copy parameters, and monitoring results. Our team, with 5+ years of experience in trading apps, has implemented over 20 copy-trading projects, and we know how to avoid such issues. Our experience guarantees deadlines and high quality.
How is a signal structured for copy-trading?
A signal is not just a notification "buy BTC". It's a structured object with enough context for automatic execution:
struct TradingSignal: Codable {
let id: UUID
let masterId: String
let pair: String // "BTC/USDT"
let side: TradeSide // .long, .short
let entryPrice: Decimal? // nil for market orders
let takeProfit: [Decimal] // multiple TP levels
let stopLoss: Decimal
let leverage: Int? // for futures
let riskPercent: Decimal // % of subscriber's deposit
let comment: String?
let publishedAt: Date
let validUntil: Date? // signal expires
}
riskPercent instead of a fixed amount — because subscribers have different deposits. 2% of $1,000 and 2% of $50,000 are different amounts but identical risk.
Signal delivery: latency matters
A signal to enter a position is time-critical. The price moves while the signal travels. Latency requirements depend on the master's strategy: for swing trading (positions held for days), push with a 5-10 second delay is sufficient. For scalping, WebSocket is mandatory — push is too slow. WebSocket, standardized protocol per RFC 6455, ensures latency <1 second, which is 10 times faster than push notifications — this is the key comparison for choosing the stack.
WebSocket for active users in the app. The backend broadcasts the signal to all connected subscribers of the master simultaneously.
FCM/APNs push for background notifications. An important nuance: push is not guaranteed delivery — FCM may buffer. For trading signals this is unacceptable. Therefore, when opening the app, always synchronize missed signals via GET /signals?since={lastReceivedAt}.
// Android — receiving and processing a signal
class SignalReceiver @Inject constructor(
private val signalRepository: SignalRepository,
private val orderExecutor: OrderExecutor,
private val notificationManager: AppNotificationManager,
) {
suspend fun handle(signal: TradingSignal) {
signalRepository.save(signal)
val subscription = signalRepository.getSubscription(signal.masterId) ?: return
if (!subscription.autoExecute) {
// Notification only, user decides manually
notificationManager.showSignal(signal)
return
}
// Auto-execution with checks
val account = accountRepository.getCurrent()
val orderSize = account.balance * subscription.riskPercent / 100
if (orderSize < exchange.minimumOrderSize(signal.pair)) {
notificationManager.showError("Insufficient balance to execute signal")
return
}
val result = orderExecutor.execute(signal, orderSize)
notificationManager.showExecutionResult(signal, result)
}
}
How to configure copying parameters?
Each subscriber configures parameters separately for each master:
Position size:
- Fixed % of deposit (follow master's risk)
- Fixed amount in USDT
- Multiplier of master's size (e.g., 0.5x if the master's volume is too large)
Signal filters:
- Long only / Short only / Both directions
- Pairs (allow only BTC, ETH; ignore altcoins)
- Maximum leverage (do not copy if master uses > 10x)
- Maximum number of simultaneous positions
Execution mode:
- Auto (immediately upon signal receipt)
- With confirmation (push → user taps "Execute")
- Notifications only (no execution, monitoring master's strategy)
The settings form is a key UX element. The user must understand the consequences of each parameter. For % of deposit — show calculation: "With a deposit of $2,000 and risk of 2% — $40 per trade."
Step-by-step guide to setting up copying:
- Select a master in the catalog.
- Set the risk percentage of deposit.
- Configure filters by pairs and leverage.
- Choose execution mode: auto, with confirmation, or notifications only.
- Confirm subscription.
Master screen: what the subscriber sees
The master's profile contains their trading metrics, not marketing text:
| Metric | Value |
|---|---|
| Win Rate | 64% |
| Profit Factor | 1.87 |
| Max Drawdown | −18.4% |
| Sharpe Ratio | 1.31 |
| Trades (30d) | 142 |
| Subscribers | 2,840 |
| Monthly PnL | +12.3% |
The master's equity curve is mandatory. Subscribers must see not just "+30% per year" but details: the presence of a prolonged drawdown plateau, a sharp rise at the beginning and stagnation afterward.
My results as a copier
A separate screen — PnL from copying a specific master. Data differs from the master's: different execution prices (slippage), different entry times (signal delivery delay), different position sizes.
Comparison: master's equity curve vs. my results on the same chart. If the discrepancy is large — analyze reasons (slippage, missed signals, filter limits).
// iOS, SwiftUI — comparing curves — Apple Documentation
Chart {
ForEach(masterEquity) { point in
LineMark(
x: .value("Date", point.date),
y: .value("PnL", point.pnl),
series: .value("Type", "Master")
)
.foregroundStyle(.blue)
}
ForEach(myEquity) { point in
LineMark(
x: .value("Date", point.date),
y: .value("PnL", point.pnl),
series: .value("Type", "My Results")
)
.foregroundStyle(.green)
}
}
.chartLegend(.visible)
Masters search and rating
Masters catalog with filters: by win rate, by drawdown, by number of trades, by activity period (minimum 3 months of active trading). Default sorting by Sharpe Ratio — the only metric that accounts for both return and risk simultaneously.
Master card in the list — compact: avatar, nickname, 3 key metrics, mini sparkline equity curve, "Subscribe" button.
What's included in the work
- Signal delivery via WebSocket + FCM/APNs with missed signal synchronization
- Copy settings form with filters and position size calculation
- Master profile with metrics and equity curve
- My results screen with comparison to master
- Masters catalog with filtering and rating
- Signal history: received, executed, missed (with reason)
More about signal filtering
Signal filtering allows the subscriber to limit risk. For example, exclude trading altcoins with high volatility or limit maximum leverage. All filters are applied before execution, preventing unwanted trades.Timeline
| Role | Features | Timeline |
|---|---|---|
| Copier (subscriber) | Signals, settings, results | 10–14 days |
| Master | Publishing, subscribers, analytics | 7–10 days |
| Full system | Catalog, ratings, both roles | 20–28 days |
Cost is calculated individually after requirements analysis. Copying profits can reach $500 per month, and savings on slippage up to $200 per year. Contact us to discuss your project — we implement the full cycle of signal system development. Request a demo: we will assess the architecture, timeline, and budget. Get a consultation on your project — we will evaluate the architecture and propose the optimal solution.