Modern RPN vs Greyline FT8
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Modern RPN
A minimalist reverse Polish notation calculator for iOS devices. It offers Standard, Binary, and Hex modes for quick calculations and programmer-friendly conversions, featuring a clean interface and a 4-level stack.
- Reverse Polish Notation (RPN) input
- Standard, Binary, and Hex modes
- 4-level visible stack
- Calculation history
- Saved session state
- Clean dark interface
Read full descriptionHide full description
Modern RPN is a minimalist reverse polish notation calculator for iPhone and iPad, with Standard, Binary, and Hex modes for fast everyday math and programmer-friendly conversions. Use a clean 4-level stack, instant mode switching, calculation history, and saved session state to move quickly without clutter. Features: • True RPN input with ENTER to push or duplicate values • Standard, Binary, Financial, and Hex calculator modes • Mode-aware entry and display formatting • 4-level visible stack: T, Z, Y, X • Core operations: add, subtract, multiply, divide • Stack tools: POP, X/Y swap, sign toggle, backspace, and all clear • Calculation history with timestamps • History filtering by All, Standard, Binary, Financial, or Hex • Saved session state for your current mode, stack, and in-progress input • Clean dark interface designed for focus and readability • No accounts, no ads, no data collection Modern RPN is designed for people who want the speed of a classic RPN calculator with a modern iOS interface.
Greyline FT8
This app provides a portable digital ham radio experience for field operations on iOS devices. It automates callsign lookups, displays real-time spot data, and offers automated calling or manual control for QSOs. Features include intelligent frequency selection, audio delay adjustment, and direct logging to QRZ.
- Field-ready digital ham radio
- Automated callsign and DXCC lookups
- Real-time PSK Reporter spot data
- Automated CQ Gatherer and Hunter modes
- Intelligent automatic frequency selection
- Direct-to-QRZ logging and ADI export
Read full descriptionHide full description
Greyline FT8 is a highly portable, capable amateur radio app designed specifically for field operation with an iOS device. I designed this app because I got very used to my full-stack FT8 solution: GridTracker, WSJT-X, PSK Reporter, WRL Desktop, several browser tabs, and more. But I didn't want the bulk and weight of a full Windows PC in the field. At the same time, while there are excellent and lightweight FT8 iOS solutions out there, they were lacking features I really wanted. Greyline is everything you need and nothing you don't. It automatically locates your grid square, performs callsign and calling station DXCC lookups (internet access required), and can even show you real-time spot data from PSK Reporter. Want to adjust your directional antenna? Now you've got the info you need to do it! Greyline also incorporates automated calling features. Gatherer mode calls CQ, responds to the first reply it gets, finishes the QSO and returns to calling CQ all without your input. On the other side of things, Hunter mode listens for CQ calls and pounces on them, finishing a QSO then returning to the live band to find the next. Or, take control of the conversation yourself with standard mode. That's the experience you're already used to from WSJT-X and other digital mode apps. Some other noteworthy features are: - Intelligent automatic free frequency selection - Dynamically adjusted audio delay for virtually drift-free message timing - PSK Reporter integrated Live Spots - Direct-to-QRZ, WRL and private Cloudlog logging and ADI export - Configurable waterfall settings - CQ addendums - CQ filtering for contesting and general courteous operation - Configurable retransmissions - Intelligent log recovery (didn't get that last 73 but want to log the contact anyway? Now you can!) - Log import and export - Antenna tuning - POTA Autospotting - One touch POTA activation and POTA.app-compatible ADIF export - Multiple POTA activation support - And so much more! Greyline uses audio VOX and not serial PTT. Most radios support this with simple cabling or an audio interface like a Digirig. For helpful tips on cabling and configuring popular radios, visit the Support URL below. Built by a ham, for hams, I'm very open to your feedback and hope Greyline can be your field companion. Want to share your own Field Notes (https://greylineft8.com/fieldnotes.html)? Email me at support@greylineft8.com!
Screenshots
Verdict
The clearest difference is ratings volume: Greyline FT8 at 15 against Modern RPN's 1. Greyline FT8 also leads on chart position (#78 vs unranked). Modern RPN's advantage is review sentiment (100% vs 90%) and price ($2.99 vs $3.99). On rating, update cadence, ads and in-app purchases 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
Modern RPN costs $2.99 and Greyline FT8 $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 5.0 for Modern RPN against 4.9 for Greyline FT8. That said, the two scores are not equally well evidenced: Greyline FT8 has 15 ratings behind it against 1, so its average is the more settled of the two. Written reviews are what separate them: 100% of Modern RPN's written reviews are positive against 90% of Greyline FT8's.
Modern RPN ships an update every 5 days, Greyline FT8 every 4 days. Both last shipped on October 31, 2026.
| Parameter | Modern RPN | Greyline FT8 |
|---|---|---|
| Price | $2.99 — better | $3.99 |
| Rating | 5.0 (1 ratings) — better | 4.9 (15 ratings) |
| Positive reviews | 100.0% of reviews — better | 90.0% of reviews |
| Number of ratings | 1 | 15 — better |
| Update frequency | Every 5 days | Every 4 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Best chart rank | — | #78 — better |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 26.2 — better | 26.5 |
| Further details — not scored | ||
| Size | 2 MB | 18 MB |
| Age rating | 4+ | 4+ |
| Developer | Kevin Flathers | JONATHAN MARK SCHULMAN |
Customer experience
Modern RPN
Greyline FT8
In-app purchases
Modern RPN
No in-app purchases
Greyline FT8
No in-app purchases









