Backtest Now vs GEM
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Backtest Now
Analyze investment strategies with historical market data. Test portfolios, including synthetic leveraged ETFs, and view results offline. Offers comprehensive performance analytics for data-driven investing.
- Synthetic Leveraged ETF Backtesting
- Offline Access to Results
- Backtesting Engine (1928-present)
- Comprehensive Performance Analytics
- Supports Stocks, ETFs, Mutual Funds
- CAGR and Sharpe Ratio Analysis
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Analyze your investment approach with Backtest Now, the portfolio analysis app that lets you test investment strategies using decades of historical market data. While internet is required to fetch market data and run new backtests, all calculated results are stored locally on your device - review your portfolio performance anytime, anywhere, even without an internet connection. Key Features: Synthetic Leveraged ETF Backtesting • Backtest leveraged ETFs before they existed! • Analyze portfolio performance during historical crises • SPX 3X/2X/-2X/-3X data since 1928 • NDX 3X/2X/-2X/-3X data since 1985 • DJI 3X/2X/-2X/-3X data since 1992 • Test how 3X ETFs would have performed during Dot-com bubble & 2008 crisis Offline Access to Your Results • View all saved backtest results without internet • Access portfolio performance metrics anytime offline • Your calculated data stays on your device, always available • Internet only needed for running new backtests Backtesting Engine • Test portfolios from 1928 to present with real market data • Compare against S&P 500 (VFINX) benchmark automatically • Support for stocks, ETFs, mutual funds, and synthetic leveraged ETFs Comprehensive Performance Analytics • CAGR (Compound Annual Growth Rate) analysis • Sharpe Ratio for risk-adjusted returns • Annual returns breakdown • All metrics viewable offline once calculated All data is stored locally on your device for offline accessibility. No account required, just powerful investment analysis at your fingertips - online or offline. Start testing your investment strategies today and invest with confidence! Download now and take control of your financial future with data-driven insights.
GEM
This app provides a data-driven monthly signal for investment decisions based on a dual-momentum strategy. It helps users choose between US stocks, international stocks, and safe assets like Treasury bills, offering backtesting and performance tracking.
- Monthly investment signal
- Dual-momentum strategy implementation
- Backtesting and performance tracking
- Customizable ETF selection
- Smart notifications
- Pro subscription for advanced features
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GEM Calculator is a free investment signal app that implements the Global Equity Momentum (GEM) strategy — a proven dual-momentum approach developed by Gary Antonacci to help investors decide between US stocks, international stocks, and safe assets like Treasury bills. Stop guessing. Get a clear, data-driven monthly signal telling you exactly what to hold. HOW IT WORKS The GEM strategy uses two simple rules every month: 1. Safety Check - Is the US stock market trending up or down? If down, move to safe assets. 2. Pick the Winner - If markets are trending up, compare US vs international stocks and hold whichever has stronger 12-month momentum. That's it. One decision per month. No day trading, no complex analysis. MONTHLY INVESTMENT SIGNAL Open the app and instantly see this month's signal: - LONG SPY — Hold US equities - LONG VEU — Hold international equities - CASH BIL — Move to Treasury bills (risk-off) The signal includes a buffer indicator showing how far the market is from a trend reversal, plus a countdown to the next monthly update. BACKTEST & PERFORMANCE TRACKING Don't just trust the strategy - verify it: - Full historical backtest with Dollar-Cost Averaging (DCA) simulation - Compare GEM returns vs Buy & Hold across 1, 2, 3, and 5-year periods - Maximum drawdown analysis for both strategies - Month-by-month detailed log of every signal and portfolio change - Interactive performance charts for all three asset classes CUSTOMIZABLE ETF SELECTION Tailor the strategy to your broker and region: • Choose from 30+ ETFs for each asset slot • US Equities: SPY, VOO, IVV, QQQ, and more • International Equities: VEU, VXUS, EFA, EIMI.L, AMUN.PA • Safe Assets: BIL, SHV, SGOV • Non-US listed ETFs supported for European and global investors SMART NOTIFICATIONS Never miss a signal change. Enable monthly reminders on the 1st of each month so you always know when to check your portfolio allocation. GEM PRO Upgrade to Pro for the full experience: • Monthly signal alerts pushed to your device • Extended backtest history up to 5 years • Custom ETF watchlist • Priority updates and new features WHO IS THIS FOR? • Passive investors who want a systematic, rules-based approach • Index fund investors looking to reduce drawdowns • Momentum strategy enthusiasts • Anyone tired of emotional investing decisions GEM Calculator is an educational tool. Past performance does not guarantee future results. Always do your own research before making investment decisions. You may purchase an auto-renewing subscription through an In-App Purchase. • Auto-renewable subscription • Weekly ($3.99), 3 months ($27.99) and 1 year ($79.99) durations • Your subscription will be charged to your iTunes account at confirmation of purchase and will automatically renew (at the duration selected) unless auto-renew is turned off at least 24 hours before the end of the current period. • Current subscription may not be cancelled during the active subscription period; however, you can manage your subscription and/or turn off auto-renewal by visiting your iTunes Account Settings after purchase • Privacy policy and terms of use: Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ GEM Calculator Terms of Use: https://flymate.io/terms_of_use.html GEM Calculator Privacy Policy: http://flymate.io/privacy_policy.html
Screenshots
Verdict
The clearest difference is in-app purchases: Backtest Now at none against GEM's 3. GEM's advantage is device support (3 vs 1) and iOS requirement (13.0 vs 16.4). On price, rating, ratings volume and update cadence there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. GEM sells 3 in-app purchases, starting at $0.99 per 7 days. Backtest Now asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 5.0 for Backtest Now against 5.0 for GEM. Both are backed by a comparable volume of ratings — 1 and 1 respectively.
Both ship on a similar rhythm, roughly weekly. The most recent releases landed on October 30, 2026 and October 31, 2026 respectively.
| Parameter | Backtest Now | GEM |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) | 5.0 (1 ratings) |
| Number of ratings | 1 | 1 |
| Update frequency | Weekly | Weekly |
| Ads | Yes | Yes |
| In-app purchases | No — better | Yes |
| Monetization | Ad-supported — better | Free with in-app purchases |
| Devices | iPhone | iPhone, iPad, iPod — better |
| Requires iOS | 16.4 | 13.0 — better |
| Further details — not scored | ||
| Size | 58 MB | 58 MB |
| Age rating | 17+ | 12+ |
| Developer | AVOHUB | Airemes |
In-app purchases
Backtest Now
No in-app purchases
GEM
- Weekly Plan$0.997 Days
- 3-Month Plan$10.993 Months
- Yearly Plan$39.991 Year









