Comparison

Prometheus Mobile STO vs Arrk

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

Head to head
About

Prometheus Mobile STO

Features
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Prometheus STO Mobile is a Prometheus Group Platform that is an easy-to-use interface and framework to address shut-down, turn-around, and outages of heavy assets in various industries. Prometheus Group is the leading enterprise asset management software solution provider, covering your plant maintenance, operations, and safety needs from planning to execution and beyond.

About

Arrk

Features
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Arrk is a native iPhone app for your Radarr and Sonarr servers. Browse your library, add missing titles, choose releases and track downloads without opening a browser. • Connect directly to your servers over local Wi-Fi or a VPN such as Tailscale. No Arrk account and no cloud relay. • Server addresses and API keys stay securely in your iPhone keychain. • Automatic discovery finds Radarr and Sonarr on your network, so you do not need to look up IP addresses or ports. • See upcoming movies and episodes from every server in one calendar, grouped by date, with premieres and finales highlighted. • Browse each library as a fast poster grid or compact list, with search, sorting and filters for available, missing and monitored titles. • See artwork, cast, ratings, seasons and files together on clear, detailed pages. • Add titles using your existing quality profiles and root folders, or search releases manually and compare quality, size and seeders. • View both queues on one screen, follow progress in real time and get notified when a download finishes. Server health and free disk space are always close at hand. • Search your history of grabs, imports and failures, with the tools you need to deal with anything that gets stuck. • Make it yours with an accent colour, light or dark mode, haptics and animations. Available in English, Italian, Spanish, German and French. Arrk requires a Radarr and/or Sonarr installation that your iPhone can reach over local Wi-Fi or VPN.

Screenshots

Prometheus Mobile STO4 screens
Arrk4 screens

Verdict

The call

The clearest difference is update cadence: Arrk at every 3 days against Prometheus Mobile STO's every 2 months. Prometheus Mobile STO's advantage is device support (3 vs 1) and iOS requirement (13.0 vs 16.4). On price, ads and in-app purchases there is nothing between them.

Scored on Price Ā· Rating Ā· Positive reviews Ā· Number of ratings Ā· Update frequency Ā· Ads Ā· In-app purchases Ā· Monetization Ā· Best chart rank Ā· Devices Ā· Requires iOS

CostPrice Ā· In-app purchases Ā· Ads Ā· Monetization

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

UpkeepUpdate frequency

Prometheus Mobile STO ships an update every 2 months, Arrk every 3 days. The most recent releases landed on October 19, 2026 and October 16, 2026 respectively.

Scorecard3 real differences Ā· 3 level
Prometheus Mobile STO versus Arrk: the parameters behind the verdict, then further details
ParameterPrometheus Mobile STOArrk
PriceFreeFree
Update frequencyEvery 2 monthsEvery 3 days — better
AdsNoNo
In-app purchasesNoNo
DevicesiPhone, iPad, iPod — betteriPhone
Requires iOS13.0 — better16.4
Further details — not scored
Size34 MB49 MB
Age rating17+4+
DeveloperPrometheus Group, IncAlessandro Mazzon

In-app purchases

None

Prometheus Mobile STO

No in-app purchases

None

Arrk

No in-app purchases

Questions

Is Prometheus Mobile STO free?
Prometheus Mobile STO is free to download, with no in-app purchases.
Is Arrk free?
Arrk is free to download, with no in-app purchases.
Do Prometheus Mobile STO or Arrk have ads?
Neither Prometheus Mobile STO nor Arrk shows ads.
Which is updated more often, Prometheus Mobile STO or Arrk?
Prometheus Mobile STO ships an update every 2 months, and Arrk every 3 days. Most recently, Prometheus Mobile STO was updated on October 19, 2026 and Arrk on October 16, 2026.

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