Comparison

CO2 sensor vs Frequency Analyzer

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

Head to head
About

CO2 sensor

Monitor CO2, temperature, and humidity levels in real-time using a Bluetooth sensor. Save readings with location data and sync them across Apple devices via iCloud. View historical data on a map.

Highlights
  • Real-time CO2, temperature, and humidity readings
  • Bluetooth sensor integration
  • Save readings with location
  • iCloud sync across devices
  • Map view of saved readings
  • Open source code available
Features
Read full description

Read CO2, temperature, and humidity from your Bluetooth Sensirion SCD-41 sensor in realtime. Save your readings with your current location and have it sync across your devices via iCloud. See previously saved readings with a map of the location that those readings were taken. Works across iPhone, iPad, and macOS devices. Open source code: https://github.com/sighmon/ios-ble-co2-sensor

About

Frequency Analyzer

Transform your device into a professional audio analysis tool with advanced FFT analysis, SPL monitoring, and detailed visualizations. Record, analyze, and export audio data with precision calibration and multiple weighting filters.

Highlights
  • Real-time FFT analysis
  • Calibrated SPL measurements
  • 32-bit float audio recording
  • Synchronized video recording
  • Spectrogram and octave band analysis
  • Export WAV, CSV, images, and videos
Features
Read full description

Transform your device into a professional-grade audio analysis suite with industry-leading 32-bit float processing, precision calibration tools, and comprehensive visualization capabilities. PROFESSIONAL ACOUSTIC MEASUREMENT • Real-time FFT analysis with configurable window sizes up to 4096 points • Reference SPL measurement with calibrated sound pressure level monitoring • Professional microphone correction with frequency-specific calibration curves • Reference tone calibration for precise frequency measurements • Configurable time averaging (0-1000ms) for stable, accurate readings • Industry-standard weighting filters: dBA, dBC, dBZ, and linear magnitude • Multiple window functions: Hanning, Hamming, Blackman ADVANCED VISUALIZATION MODES • High-resolution spectrum analyzer with peak detection • Real-time waveform display • Professional spectrogram • Octave band analysis • Amplitude tracking over time • Total level monitoring with min/max/average statistics POWERFUL RECORDING & ANALYSIS • High-quality 32-bit float audio recording and playback • Synchronized video recording with audio analysis overlay • Event tracking system with timestamped notes • Playback synchronization with all recorded events and measurements • Location mapping for environmental noise surveys • Export capabilities: WAV audio, CSV data, high-resolution images and videos PRECISION DECIBEL MEASUREMENT • Calibrated SPL measurements with reference level adjustment • Real-time dB monitoring with peak hold functionality • Statistical analysis: Leq, Lmax • Configurable time averaging (0-1000ms) • Frequency-weighted noise exposure calculations • Exposure calculator for NIOSH and OSHA IDEAL FOR PROFESSIONALS • Acousticians and audio engineers • Environmental noise consultants • Musicians and sound designers • Room acoustics optimization • Industrial noise monitoring • Educational and research applications • Live sound reinforcement • Building acoustics assessment Download now and unlock the full spectrum of acoustic measurement capabilities. DISCLAIMER This is a consumer application designed for general audio analysis and educational purposes. It is not a certified measurement instrument and should not be used where legally compliant or certified measurements are required. For professional acoustic assessments requiring traceable calibration or regulatory compliance, we recommend using an external calibrated measurement microphone with certified sound level meters. EULA: https://frequency-analyzer.com/terms-and-conditions/

Screenshots

CO2 sensor4 screens
Frequency Analyzer4 screens

Verdict

The call

The clearest difference is rating: Frequency Analyzer at 4.5 against CO2 sensor's 3.4. Frequency Analyzer also leads on update cadence (every 8 days vs every 12 months) and ratings volume (169 vs 7). CO2 sensor's advantage is in-app purchases (none vs 11) and device support (4 vs 1). On price and ads 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. Frequency Analyzer sells 11 in-app purchases, starting at $2.99 per 7 days. CO2 sensor asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Frequency Analyzer holds the better App Store score, 4.5 against 3.4. That said, the two scores are not equally well evidenced: Frequency Analyzer has 169 ratings behind it against 7, so its average is the more settled of the two.

UpkeepUpdate frequency

CO2 sensor ships an update every 12 months, Frequency Analyzer every 8 days. The most recent releases landed on October 3, 2026 and October 12, 2026 respectively.

Scorecard7 real differences · 3 level
CO2 sensor versus Frequency Analyzer: the parameters behind the verdict, then further details
ParameterCO2 sensorFrequency Analyzer
PriceFreeFree
Rating3.4 (7 ratings)4.5 (169 ratings) — better
Positive reviews—10.0% of reviews
Number of ratings7169 — better
Update frequencyEvery 12 monthsEvery 8 days — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad, iPod, Mac — betteriPhone
Requires iOS15.6 — better17.2
Further details — not scored
Size0 MB35 MB
Age rating4+4+
DevelopersighmonManfred Kuegel

Customer experience

CO2 sensor

All ratings7 ratings
Positive57.1%
Neutral28.6%
Negative14.3%

Frequency Analyzer

All ratings169 ratings
Positive88.2%
Neutral3.6%
Negative8.3%
Written reviews10 reviews
Positive10.0%
Neutral0.0%
Negative90.0%

In-app purchases

None

CO2 sensor

No in-app purchases

11 purchases

Frequency Analyzer

Subscriptions10
  • Frequency Analyzer Pro Weekly3 Days trial$2.997 Days
  • Frequency Analyzer Pro Monthly7 Days trial$3.991 Month
  • Frequency Analyzer Pro Monthly$3.991 Month
Show 7 more
  • Frequency Analyzer Pro Monthly7 Days trial$4.991 Month
  • Frequency Analyzer Pro Monthly$4.991 Month
  • Frequency Analyzer Pro Monthly3 Days trial$4.991 Month
  • Frequency Analyzer Pro Annual7 Days trial$29.991 Year
  • Frequency Analyzer Pro Annual7 Days trial$44.991 Year
  • Frequency Analyzer Pro Annual$44.991 Year
  • Frequency Analyzer Pro Annual3 Days trial$44.991 Year
One-time1
  • Pro access for lifetime$89.99

Questions

Is CO2 sensor free?
CO2 sensor is free to download, with no in-app purchases.
Is Frequency Analyzer free?
Frequency Analyzer is free to download, with in-app purchases available.
Which has better reviews, CO2 sensor or Frequency Analyzer?
Frequency Analyzer is rated higher. CO2 sensor averages 3.4 out of 5 from 7 ratings, while Frequency Analyzer averages 4.5 from 169 ratings.
Do CO2 sensor or Frequency Analyzer have ads?
Neither CO2 sensor nor Frequency Analyzer shows ads.
Which is updated more often, CO2 sensor or Frequency Analyzer?
CO2 sensor ships an update every 12 months, and Frequency Analyzer every 8 days. Most recently, CO2 sensor was updated on October 3, 2026 and Frequency Analyzer on October 12, 2026.

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