Comparison

CW Decoder vs Hotaru

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

Head to head
About

CW Decoder

This application uses AI for high-accuracy Morse code decoding. It offers real-time signal processing for steady performance in noisy conditions. A free version allows for short decoding sessions, while a paid upgrade provides unlimited use and advanced features.

Highlights
  • AI-driven decoding
  • Real-time signal processing
  • Adjustable speed and thresholds
  • Decodes letters, numerals, and prosigns
  • Built-in microphone input
  • USB-C audio input (full version)
  • Scrollable decoded text
Features
Read full description

A high-accuracy Morse code decoder An AI model now drives the decoding, raising the hit rate on real on-air signals. Sample-by-sample signal processing keeps it steady in noise. Try the free version first and hear what it can pull out of the band. ■ Free version vs. Full Version The decoding engine itself is free for everyone to try. [Free version] • Each decoding session runs up to 2 minutes (restart as often as you like) • Standard font • Audio input from the built-in microphone only → Ideal for trying the app out or checking a short QSO. [Full Version (paid add-on)] • No time limit — built for long ragchews and for leaving it running while you monitor • Font settings — pick the typeface and size that read best for you • USB-C audio input — wire it straight to your rig and decode without the room getting in the way → Recommended if you want it on the desk for real operating, or a study setup you never have to babysit. ■ Features and technology (Real-time decoding) • Speed range: 5–50 WPM (speed and thresholds adjust themselves) • Detection range: 400 Hz – 900 Hz (locks onto the strongest signal) (What it decodes) • Letters, numerals and punctuation • Prosigns, and characters run together the way operators actually send them (Audio input: built-in microphone or USB-C) • Built-in microphone: no cable, nothing to set up. Point it at the speaker and go. • USB-C input (Full Version): connect any USB Audio Class device with a cable and it is recognised on the spot. No driver, no settings screen to find. • Plugging in switches the input over automatically; unplugging hands it back to the built-in microphone. • Taking audio straight from your rig's headphone output or an audio interface keeps conversation, traffic and household noise out of the decode. (Input source indicator) • The icon at the top left of the screen shows which input is in use at a glance: Microphone icon — the built-in microphone Connector icon — a USB-C device (shown in blue) • Plug or unplug the cable and the icon follows along on its own. • Connect a USB device before purchasing and a small lock appears. Tap it for details about the Full Version. • In landscape the icon moves to the button row at the bottom. (Signal processing) • Band-pass filter: a narrow window that cuts everything you did not tune for • AGC: tracks changes in signal strength and rides out fading • Noise blanker: removes spike noise using median absolute deviation • State stabilisation: multi-sample buffering so noise does not trip a false element ■ Built for operating, not just demos • Scrollable text, so anything you missed is still there to go back to • Locks firmly onto the 400 Hz – 900 Hz range where CW actually lives • A visual read-out that backs up what your ears are doing • A direct USB-C connection to the rig gives you the same steady copy in the shack or out portable ■ Who it is for (New to Morse) For anyone curious about Morse who is not sure where to start. Hearing it and reading it at the same time means you can check yourself as you go, which makes the learning stick far faster. (Licensed amateurs) • Practice: compare the decode against your own copy and find the characters you keep missing • Contests: a second pair of ears on fast CW, and a way to check a log entry • Portable: leave the laptop at home. A phone is the whole receiving setup. • Direct connection: over USB-C the copy stays solid even somewhere noisy (Returning and experienced operators) As a backstop for ears that are not what they were, or simply to make a long watch less tiring. Strong filtering keeps weak and crowded signals readable. Note: USB-C audio input requires a device with a USB-C port (iPhone 15 or later, USB-C iPad models) and a USB Audio Class compatible device. Note: Microphone access is used only to analyse the signal. Nothing is recorded, stored or transmitted. Audio arriving over USB-C uses the same permission.

About

Hotaru

Features
Read full description

Hotaru is a virtual penlight app that lights up both your iPhone and Apple Watch — for concerts, festivals, sports games, and any moment that calls for cheering. Keep your phone in your pocket and change colors right from your wrist. Just rotate the Digital Crown to cycle through 16 colors. Even in the darkest venue, every control happens at your fingertip. 【 Features 】 ■ Apple Watch as the main control Raise your wrist and rotate the crown to switch colors. The Apple Watch screen itself glows in your chosen color, working as a small penlight on its own. Single-tap to light up, double-tap to turn off, long-press for an immediate blackout. ■ 16 curated colors Snow, Crimson, Coral, Tangerine, and more — 16 refined colors that shine at the venue, cycling smoothly with the crown. ■ Show your message inside the penlight Display the name of your favorite, a heartfelt message, or any text you love — right inside the penlight. Short messages appear large and centered; longer messages scroll smoothly like an LED message board. Mix Latin letters, kanji, hiragana, katakana, and emoji in any combination. Beautiful LINE Seed JP Bold typography. Tap any of your 8 most recent entries to reuse them instantly. ■ Vertical / Horizontal text (v1.4 new) Toggle between Japanese-style vertical writing and Western-style horizontal layout right from the input sheet. Match the style to your show — a traditional Japanese live atmosphere or a clean, social-media-ready look. ■ Landscape LED ticker mode (v1.4 new) Set your phone down sideways and the penlight transforms into a horizontal LED ticker. Perfect for stadiums, festivals, and marathon cheering — anywhere you want your message to be seen from a distance. 【 Beyond concerts — sports & cheering 】 Hotaru is not just for live music. The 16-color palette and LED ticker mode shine just as bright at: · Baseball stadiums — pick your team's color and rally with chants · Soccer / football matches — display your player's name or number · Marathons — cheer your runner with their name from the roadside · Festivals & school events — light up the crowd in your team's color Whatever you want to cheer for, Hotaru turns your phone into a personal cheering tool. ■ Brightness lock In fullscreen mode, the app overrides iOS auto-brightness and locks at a fixed value. Match the brightness of other penlights in the venue. Adjust the maximum from the Settings tab. ■ Dark UI Bright white screens can be distracting in a venue. Switch to Dark in Settings and the entire UI goes low-light, while the glow color in fullscreen mode stays unaffected. ■ Built-for-the-dark haptics Every action provides tactile feedback so you never need to look down. ■ Safety reminders A drop-prevention modal appears on first launch, and a wrist-strap reminder pops up before entering fullscreen mode. 【 Privacy 】 · No ads · No signup (no email, no social login) · All data stays on your device · Zero third-party SDKs, zero analytics 【 Before you use 】 Please check your venue's smartphone usage rules before use. Always attach a wrist strap (or similar drop-prevention accessory) and slip it onto your wrist before swinging. The developer assumes no responsibility for any accidents or damages resulting from the use of this app. 【 About 】 KARABINA LLC (Tokyo, Japan) A small studio building utilities for live show fans.

Screenshots

CW Decoder3 screens
Hotaru4 screens

Verdict

The call

The clearest difference is in-app purchases: Hotaru at none against CW Decoder's 1. On price, update cadence, ads 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

Both are free to download. CW Decoder sells 1 one-off in-app purchase. Hotaru asks for nothing beyond the download.

UpkeepUpdate frequency

CW Decoder ships an update every 8 days, Hotaru every 6 days. Both last shipped on October 11, 2026.

Scorecard1 real difference · 9 level
CW Decoder versus Hotaru: the parameters behind the verdict, then further details
ParameterCW DecoderHotaru
PriceFreeFree
Rating2.0 (1 ratings) — better—
Positive reviews0.0% of reviews—
Number of ratings1 — better—
Update frequencyEvery 8 daysEvery 6 days — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases—
DevicesiPhone, iPadiPhone, Apple Watch
Requires iOS17.217.0 — better
Further details — not scored
Size12 MB8 MB
Age rating4+4+
DeveloperKeiya ChibaKARABINA, LLC

In-app purchases

1 purchases

CW Decoder

One-time1
  • Unlock Full Version$2.99
None

Hotaru

No in-app purchases

Questions

Is CW Decoder free?
CW Decoder is free to download, with in-app purchases available.
Is Hotaru free?
Hotaru is free to download, with no in-app purchases.
Do CW Decoder or Hotaru have ads?
Neither CW Decoder nor Hotaru shows ads.
Which is updated more often, CW Decoder or Hotaru?
CW Decoder ships an update every 8 days, and Hotaru every 6 days. Most recently, CW Decoder was updated on October 11, 2026 and Hotaru on October 11, 2026.

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