Comparison

Silent Observer vs DOCS II

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

Head to head
About

Silent Observer

Features
Read full description

Silent Observer provides citizens in Kent County, Michigan a safe and anonymous way to report a crime. Silent Observer is most interested in information about serious crimes that affect the safety and well-being of your neighborhood, community and school. Tips on serious crimes like murder, assault, rape, robbery, weapons, felony warrants, drug dealing, and burglary as well as code of conduct infractions occurring on school grounds is information Silent Observer would like to receive. That information is then sent to police for follow-up and if your tip leads to the arrest, you may be eligible for a reward.

About

DOCS II

This app automates the capture and reporting of visible emission observations for air quality compliance. It uses location data, weather, and sun angles to document opacity levels, helping users avoid costly fines. The tool generates compliance archives for regulated sources.

Highlights
  • Automated Visible Emission Observation (VEO) capture
  • Integration with Google Maps, compass, and inclinometers
  • Real-time weather and sun angle data
  • Opacity level documentation
  • Automated VEO report generation
  • Compliance archive creation
Features
Read full description

DOCS II is developed by Virtual Technology, LLC, located in Rio Rico, Arizona. Air Quality has been driven by Opacity Emission standards since the 1800s, with Opacity percentages used to determine airflow requirements for various coal-fired boilers. Every locality in the USA has a standing Visible Emission Opacity limit of no more than 40% Opacity over any six minutes. Visible Emission Standards lowering this opacity limit to 20% / 5% / Zero are not uncommon in the USA, with enforcement of air pollution regulations at the federal, state, and local levels. Failure to adhere to these regulations is very costly, as violations of opacity limits can result in fines of $25,000 per source per day. The most common methods to monitor opacity levels are EPA Method 9, EPA Alternative Method 082, ASTM D7520-16, Digital Camera Opacity Technique, using EPA Method 22. The methods are a visible emission indicator of smoke or no smoke, followed by a Visible Emission Observation (VEO) to determine Opacity. A Visible Emissions Manager completely automates the entire capture of information needed for a Visible Emission Observation. Using Google Maps, compass, inclinometers, distance calculations, online weather, and sun angle data, the VEO is documented with populated data. With the local data captured, the VEO is uploaded to the Virtual Technology LLC servers, and a completed VEO report is generated to create the compliance archive. Nuisance ‘visible’ emissions accounted for over 85% of Air Quality complaints until today are still monitored exclusively by the highly subjective human observation method 9. Visible Emissions Manager is the solution for measuring Opacity and managing complaints of Nuisance Visible Emissions and regulated sources.

Screenshots

Silent Observer4 screens
DOCS II4 screens

Verdict

The call

The clearest difference is iOS requirement: Silent Observer at 9.0 against DOCS II's 15.0. On price, 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Silent Observer ships an update every 34 months, DOCS II every 58 months. The most recent releases landed on September 17, 2026 and October 2, 2026 respectively.

Scorecard1 real difference · 8 level
Silent Observer versus DOCS II: the parameters behind the verdict, then further details
ParameterSilent ObserverDOCS II
PriceFreeFree
Rating—5.0 (1 ratings) — better
Number of ratings—1 — better
Update frequencyEvery 34 months — betterEvery 58 months
AdsNoNo
In-app purchasesNoNo
Monetization—Free
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS9.0 — better15.0
Further details — not scored
Size30 MB91 MB
Age rating4+4+
DeveloperNavigate360, LLCVirtual Technology LLC

In-app purchases

None

Silent Observer

No in-app purchases

None

DOCS II

No in-app purchases

Questions

Is Silent Observer free?
Silent Observer is free to download, with no in-app purchases.
Is DOCS II free?
DOCS II is free to download, with no in-app purchases.
Do Silent Observer or DOCS II have ads?
Neither Silent Observer nor DOCS II shows ads.
Which is updated more often, Silent Observer or DOCS II?
Silent Observer ships an update every 34 months, and DOCS II every 58 months. Most recently, Silent Observer was updated on September 17, 2026 and DOCS II on October 2, 2026.

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