Comparison

RPN vs DarkReader Web

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

RPN

This app simulates a vintage programmable calculator from the mid-70s, offering enhanced features beyond the original. It allows users to run existing programs, manage virtual cards, and utilize advanced functions for scientific and engineering tasks.

Highlights
  • Virtual program and data cards
  • Virtual paper tape printer
  • Database-driven card manager
  • Create, label, and organize unlimited cards
  • Share cards via email, AirDrop, Dropbox
  • Editable program listings
  • Enhanced features for more program steps and registers
Features
Read full description

A dream calculator of the mid-70's, priced at $2,500 in today's dollars (2025), right on your iPhone! RPN-67 SD is the iPhone version of RPN-67 Pro, the first complete simulation of Hewlett-Packard's legendary HP-67 programmable calculator for the iPad. Produced from 1976 to 1982, the HP-67 was a huge success among scientists, engineers and other professionals. Thousands of programs were written for it. Now you can run them right on your iPhone, with more ease and faster than ever before. To get you started quickly, run the built-in program cards, or choose from the large number of programs available as free downloads from our website. What users said: “This version permits you to use your virtual HP-67 just as you could the original – hand-held and highly portable. Congratulations to the developer for providing such an excellent and aesthetically pleasing software product." "This was my first scientific calculator in real life. It is great to have the simulator on my iPhone. The special features added make it into a HP-41 or 42S! It comes packaged with some great samples. Am having great fun with it." Features: • Virtual program and data cards • Virtual paper tape printer supports all HP-97 printer modes • Powerful database-driven card manager • Create, label, and organize a virtually unlimited number of cards • Use iTunes to effortlessly save entire card collections on your Mac/PC • Sharing: e-mail, AirDrop, Dropbox, copy, paste, print • Editable listing shows labels, targets of branches, and errors • E-mail listings and let the recipient paste the text right into RPN-67 • Print listings on any AirPrint-compatible printer • Program listing on paper tape shows subroutine nesting • Edit paper tape • E-mail paper tape, or print it via AirPrint • Cut/copy/paste displayed value or program steps • Paste existing HP-67 listings into RPN-67 SD and run them • "Live" display of stack, memory registers, flags • Show and edit program instructions • Fast: 1.5 seconds vs. 6 minutes (program HM-05, determinant of 5x5 matrix) • Low-battery indicator (iPhone charge 10% or less) • Optional high-contrast mode for working in bright ambient light • Compatible with RPN-67 Pro and RPN-97 Pro While RPN-67 SD works like a real HP-67, changing a simple setting will turn the app into a super-charged HP-67: • Up to 999 program steps, 8 subroutine levels, 6 additional flags (F4...F9) • 100 additional registers • 100 additional labels • 100 built-in constants and conversions • More than 150 additional powerful operations and functions Plus: • 15 commands to print and manipulate any range of extended registers • Unrestricted register arithmetic • Exchange x with any register • Complex numbers, hyperbolic functions • Non-volatile memory - stack, registers, program, flags, paper tape • Status indicators for prefix keys (f, g, h, STO, RCL, etc.) • Display showing thousands separators (optional) • Text output on simulated paper tape in 10 colors, even simple plotting • Stack-of-stack: push/pop the entire stack on internal stack (4 levels) • Single-step into subroutines (optional) • Powerful debugging aids, including 10 breakpoints with counters • Keycodes translated to command names while entering or single-stepping a program • Change the duration of the PAUSE command • Compress constants in programs into a single step (reversible) RPN-67 SD comes with more than 130 programs pre-installed, including HP Standard Pac, HP Business Decisions Pac, HP Math Pac I, HP Stat Pac I, and HP Surveying Pac I. The simulator has been verified to correctly run the examples given in HP Civil Engineering Pac I, HP Clinical Lab Pac, HP E.E. Pac I, HP Games Pac I, HP M.E. Pac I, HP Navigation Pac I, as well as large number of programs published in Users' Library Solutions. For more information and free program downloads visit the RPN-67 website: cuveesoft.ch/rpn67

About

DarkReader Web

Features
Read full description

Night Browsing, Reimagined Tired of being blinded by bright websites at night? DarkReader Web transforms every site into a comfortable dark mode instantly. - Enjoy easy-on-the-eyes browsing, day or night - Intelligent design preserves transparency and layout - Smooth, modern dark theme with softer light gray text for effortless reading - Works seamlessly across your favorite websites - Fast, efficient, and battery-friendly for OLED screens Why choose DarkReader Web? Because your eyes deserve comfort, your sleep deserves protection, and your browsing deserves elegance. Privacy first: We never collect any data. Browse freely and safely. Download DarkReader Web today and experience the web in a way your eyes will thank you for.

Screenshots

RPN4 screens
DarkReader Web3 screens

Verdict

The call

The clearest difference is update cadence: RPN at every 3 months against DarkReader Web's every 22 months. RPN also leads on iOS requirement (12.0 vs 17.6). DarkReader Web's advantage is price ($2.99 vs $3.99). On ads, in-app purchases and device support 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

CostPrice · In-app purchases · Ads · Monetization

RPN costs $3.99 and DarkReader Web $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

RPN ships an update every 3 months, DarkReader Web every 22 months. The most recent releases landed on October 24, 2026 and October 20, 2026 respectively.

Scorecard3 real differences · 7 level
RPN versus DarkReader Web: the parameters behind the verdict, then further details
ParameterRPNDarkReader Web
Price$3.99$2.99 — better
Rating4.6 (17 ratings) — better—
Positive reviews92.9% of reviews—
Number of ratings17 — better—
Update frequencyEvery 3 months — betterEvery 22 months
AdsNoNo
In-app purchasesNoNo
MonetizationPaid—
DevicesiPhone, iPodiPhone, iPad
Requires iOS12.0 — better17.6
Further details — not scored
Size63 MB2 MB
Age rating4+4+
DeveloperCuVee SoftwareJorge Lucioni Charalla

In-app purchases

None

RPN

No in-app purchases

None

DarkReader Web

No in-app purchases

Questions

Is RPN free?
RPN costs $3.99, with no in-app purchases.
Is DarkReader Web free?
DarkReader Web costs $2.99, with no in-app purchases.
Do RPN or DarkReader Web have ads?
Neither RPN nor DarkReader Web shows ads.
Which is updated more often, RPN or DarkReader Web?
RPN ships an update every 3 months, and DarkReader Web every 22 months. Most recently, RPN was updated on October 24, 2026 and DarkReader Web on October 20, 2026.

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