Comparison

Project Monarch Science vs Stolpersteine.app

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

Head to head
About

Project Monarch Science

This app transforms your smartphone into a receiver for tiny tracking devices attached to monarch butterflies. By crowdsourcing data, it helps scientists monitor butterfly migration patterns in unprecedented detail, aiding conservation efforts.

Highlights
  • Crowdsourced tracking network
  • Monarch butterfly migration monitoring
  • Detailed movement data
  • Habitat conservation insights
  • Utilizes Bluetooth frequency
  • Citizen science participation
Features
Read full description

Project Monarch is an effort to leverage recent advances in tracking technology, that have enabled the development of the world’s smallest tracking devices, to track Monarch migration. The tracking devices on the monarch butterflies transmit at the same frequency as Bluetooth which means that everyone with a smartphone is carrying around a receiver in their pocket! This revolutionary approach can potentially create the largest wildlife tracking receiver network in the world, but only if members of the public download and use the free Project Monarch app. These data will allow scientists to track the movements of monarch butterflies in detail never previously imagined. We will see how monarchs utilize key stopping points along migratory routes and learn more about the speed and direction of migration, helping identify the most important sites for habitat conservation and restoration. Ultimately, this technology can help guide conservation planning and lead to increases in monarch populations.

About

Stolpersteine.app

Features
Read full description

Stolpersteine (stumbling stones) are small brass memorial stones in the pavement, in front of the house where someone lived who was persecuted, deported or murdered by the Nazis. Each stone gives a name, a year of birth and what happened to that person. With this app you find the stones near you and read who lived there. The app knows more than 100,000 stones at over 42,000 addresses in more than 30 countries, from Germany and the Netherlands to Italy, Belgium and Norway. What you can do with the app: • Map: see all stones on the map and search by name, street or town. • Stories: many addresses have the life story of the people who lived there, with photos of the stones and portraits. The app can also read the story out loud. • Walking route: choose how long you want to walk (30 to 120 minutes) and the app makes a route past the stones nearby. At each stop you see who lived there. • On this day: see every day who is remembered today. • Help out: is a photo missing, or is a stone hard to read? Take a photo and send it in. • 44 languages, including English, German, French and Dutch. The app is free and has no advertising. It is made and run by Stichting 18 september, a foundation in Eindhoven, the Netherlands. Would you like to add the Stolpersteine of your town, or add to a story? Write to info@stolpersteine.app.

Screenshots

Project Monarch Science4 screens
Stolpersteine.app4 screens

Verdict

The call

Project Monarch Science and Stolpersteine.app are too close to call on the numbers: across 6 compared parameters — price, update cadence, ads and in-app purchases among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.

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

Project Monarch Science ships an update every 10 days, Stolpersteine.app fortnightly. Both last shipped on November 12, 2026.

ScorecardNo meaningful differences
Project Monarch Science versus Stolpersteine.app: the parameters behind the verdict, then further details
ParameterProject Monarch ScienceStolpersteine.app
PriceFreeFree
Rating4.0 (29 ratings) — better—
Positive reviews60.0% of reviews—
Number of ratings29 — better—
Update frequencyEvery 10 days — betterFortnightly
AdsNoNo
In-app purchasesNoNo
MonetizationFree—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.015.0
Further details — not scored
Size83 MB40 MB
Age rating4+17+
DeveloperCellular Tracking TechnologiesStichting 18 september

In-app purchases

None

Project Monarch Science

No in-app purchases

None

Stolpersteine.app

No in-app purchases

Questions

Is Project Monarch Science free?
Project Monarch Science is free to download, with no in-app purchases.
Is Stolpersteine.app free?
Stolpersteine.app is free to download, with no in-app purchases.
Do Project Monarch Science or Stolpersteine.app have ads?
Neither Project Monarch Science nor Stolpersteine.app shows ads.
Which is updated more often, Project Monarch Science or Stolpersteine.app?
Project Monarch Science ships an update every 10 days, and Stolpersteine.app fortnightly. Most recently, Project Monarch Science was updated on November 12, 2026 and Stolpersteine.app on November 12, 2026.

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