Comparison

Blue Box vs Frequency

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

Head to head
About

Blue Box

Encode and decode DTMF signals using your device's microphone or keypad. Play back tone sequences with adjustable settings, and save them for easy recall. Explore various tone systems, including trunk control and coin signals, for educational and utility purposes.

Highlights
  • Encode/decode DTMF signals
  • Adjustable tone, delay, and volume
  • US, UK, and European tone systems
  • Multi-frequency and trunk control tones
  • Coin tone sequences (Red Box mode)
  • Custom tone creation
  • Save and organize sequences
Features
Currently charting
Read full description

Blue Box is utility for encoding and decoding DTMF (Dual-Tone Multi-Frequency) or Touch Tone signals. Generate tones by using the phone style keypad or decipher tones using the device’s microphone. Tone combinations can be played back with adjustable tone, delay and pause lengths and volume. Choose from US, UK and Europe based systems. Enable Multi-frequency tones, which were a precursor to DTMF. Additional trunk control signals will be available including KP, ST1, ST2, ST3, KP/ST2. Additional tones include the Dial Tone, Ring Back Tone, Busy Signal and 2600Hz. A comma can be used as a pause character to provide extra time between tones during playback. Save and organize any number of sequences for easy recall using the Favorites feature. Choose numbers from your contacts to display and play back tones. Share an encoded or decoded number with the Phone, FaceTime or Messages app. Use Red Box mode to play coin tone sequences, including 5¢, 10¢ and 25¢ for the US system and 10p and 50p for European systems. Create a custom tone with control over individual frequencies and volumes. The custom tone can consist of any number of on and off pulses and can optionally be continuous. Record interactions with the encoder and play them back with the same timing. The recording feature works with all tones, including the dial tone, busy signal, ring back tone, 2600Hz and coins and trunk control tones. A help manual is including, with step-by-step instructions for all features. When the app is first run, pop-ups will be displayed indicating what the controls are used for. Warning: Blue Box is designed as an educational tool and utility. Do not attempt to use Blue for any illegal or malicious purposes. Blue Box can be used to assist in dialing numbers, but can not be used to manipulate digital telephone utility services. Limitations: Blue Box is software based decoding and is processor intensive. Performance may vary between devices. Tones that are less than 100 ms with pauses that are less than 100 ms are difficult to process in software. Future versions and processors may increase the reliability of faster tone sequences. If you need touch tone decoding for higher speeds, a hardware solution is recommended. Blue Box can not play tones into the iPhone phone feature while in a call. Blue Box is useful for entering numbers into touch tone operated systems such as an answering machine passcode or a dial-up service that requires the entering of several touch tones to navigate a menu system. Simply enter the numbers once and then play back the numbers into the phone's microphone with a touch.

About

Frequency

Generate precise audio frequencies for various purposes, from tuning instruments to cleaning water from speakers. Explore different waveforms and customize sound generation for unique audio experiences. Elevate your audio quality and functionality.

Highlights
  • Generate frequencies from 1 Hz to 40,000 Hz
  • Clean water/moisture from speakers
  • Produce sine, triangle, sawtooth, and square waveforms
  • Tune musical instruments
  • Select notes and octaves for specific pitches
  • Play multiple frequencies simultaneously
Features
Read full description

# GENERATE ANY TONE, FROM 1 HZ TO 40 KHZ Frequency is a tone generator. Set a pitch by hertz or by note and octave, choose a waveform, and play it. It also plays the low sweep that pushes water out of a blocked speaker. # PLAY A TONE AT ANY FREQUENCY Enter a value in hertz, or pick a note and an octave and let the app work it out. The range runs from 1 Hz to 40,000 Hz, past the top of human hearing. # CHOOSE YOUR WAVEFORM Sine, triangle, sawtooth, and square. Each has its own character, and switching between them at the same pitch is the quickest way to hear the difference. # PLAY SEVERAL TONES AT ONCE Run more than one tone together, each with its own frequency, waveform, and volume, and listen to how they interact. # CLEAN YOUR SPEAKER Water trapped in a speaker muffles it. Playing a low-frequency tone at full volume vibrates the driver and pushes the water out — the same technique a smartwatch uses to eject water after a swim. # A REFERENCE PITCH TO TUNE AGAINST Play a note at a known frequency and tune your instrument to it by ear. Frequency plays the reference; it does not listen, so nothing you play reaches the app. # TUTORIALS INCLUDED Step-by-step guides for generating tones, working with waveforms, running several at once, and cleaning a speaker. # SUBSCRIPTIONS AND AUTOMATIC RENEWAL - Your subscription includes access to the features listed above. - Payment will be charged to your Apple ID Account at confirmation of purchase. - Subscription automatically renews unless auto-renewal is turned off at least 24 hours before the end of the current period. - Your account will be charged for renewal within 24 hours prior to the end of your selected subscription period. - Subscriptions can be managed and auto-renewal turned off in your App Store Account Settings. # LEGAL Terms of Service: https://cooptimizeit.com/terms-of-service Privacy Policy: https://cooptimizeit.com/privacy-policy # SUPPORT Contact us at info@cooptimizeit.com. We reply within 48 hours.

Screenshots

Blue Box4 screens
Frequency4 screens

Verdict

The call

The clearest difference is review sentiment: Blue Box at 56% against Frequency's 0%. Blue Box also leads on rating (5.0 vs 3.9) and in-app purchases (none vs 10). Frequency's advantage is price (Free vs $4.99) and update cadence (every 10 days vs every 7 months). On ads, device support and iOS requirement 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

Frequency is free to download; Blue Box costs $4.99 up front. Frequency sells 9 in-app purchases, starting at $7.99 per 7 days. Blue Box asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Blue Box holds the better App Store score, 5.0 against 3.9. That said, the two scores are not equally well evidenced: Frequency has 24 ratings behind it against 3, so its average is the more settled of the two. Written reviews point the same way: 56% of Blue Box's written reviews are positive against 0% of Frequency's.

UpkeepUpdate frequency

Blue Box ships an update every 7 months, Frequency every 10 days. The most recent releases landed on September 11, 2026 and September 7, 2026 respectively.

Scorecard8 real differences · 3 level
Blue Box versus Frequency: the parameters behind the verdict, then further details
ParameterBlue BoxFrequency
Price$4.99Free — better
Rating5.0 (3 ratings) — better3.9 (24 ratings)
Positive reviews55.6% of reviews — better0.0% of reviews
Number of ratings324 — better
Update frequencyEvery 7 monthsEvery 10 days — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree with in-app purchases — better
Best chart rank#192 — better
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS15.0 — better16.0
Further details — not scored
Size2 MB16 MB
Age rating4+4+
DeveloperSunshine Valley SystemsOptimize IT

Customer experience

Blue Box

All ratings3 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews18 reviews
Positive55.6%
Neutral0.0%
Negative44.4%

Frequency

All ratings24 ratings
Positive75.0%
Neutral0.0%
Negative25.0%
Written reviews1 reviews
Positive0.0%
Neutral0.0%
Negative100.0%

In-app purchases

None

Blue Box

No in-app purchases

9 purchases

Frequency

Subscriptions9
  • Weekly Premium$7.997 Days
  • Weekly7 Days trial$9.997 Days
  • Weekly VIP3 Days trial$9.997 Days
Show 6 more
  • Monthly Premium$17.991 Month
  • Monthly7 Days trial$19.991 Month
  • Annual VIP$24.991 Year
  • Annual Premium$24.991 Year
  • Annual VIP3 Days trial2 variants$29.991 Year
  • Annual7 Days trial$29.991 Year

Questions

Is Blue Box free?
Blue Box costs $4.99, with no in-app purchases.
Is Frequency free?
Frequency is free to download, with in-app purchases available.
Which has better reviews, Blue Box or Frequency?
Blue Box is rated higher. Blue Box averages 5.0 out of 5 from 3 ratings, while Frequency averages 3.9 from 24 ratings.
Do Blue Box or Frequency have ads?
Neither Blue Box nor Frequency shows ads.
Which is updated more often, Blue Box or Frequency?
Blue Box ships an update every 7 months, and Frequency every 10 days. Most recently, Blue Box was updated on September 11, 2026 and Frequency on September 7, 2026.

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