FLEXKEY
OPTIMIST Health & Fitness In-app purchases
Subscriptions take saunas from entertainment to everyday life. For a monthly fee of 4,980 yen (5,478 yen including tax), you can visit the sauna as many times as you like during off-peak hours. A health habit app that allows you to enter and exit the sauna smartly.
- Downloads
- 100+
- on Google Play
- Price
- Free
- In-app purchases
- Updated
- Mar 14
- 2026 · v1.0.9
Screenshots
About FLEXKEY
Take saunas from a leisure activity to a daily routine with a subscription. For a monthly fee of ¥4,980 (¥5,478 including tax), you can visit affiliated facilities as many times as you like during their off-peak hours. This health habit app allows you to smartly enter and exit the sauna using a QR code.
FLEXKEY was created to make saunas more accessible and easier to maintain. Simply open the app and scan the facility's QR code to enter and exit. No need to go through the reception process, providing a stress-free, smooth experience. Another great feature is that sauna use is limited to affiliated facilities' "off-peak hours (low-occupancy)," allowing you to enjoy the sauna in peace and quiet while avoiding crowds. It's designed for both those who want to go to the sauna every day and those who want to make it a healthy habit.
⸻
[Key Features]
1. Unbeatable Cost Performance
FLEXKEY allows you to visit the sauna once a day for a monthly fee of ¥4,980 (¥5,478 including tax). If you visit every day, the effective usage fee per visit is just ¥183. For less than the cost of a can of coffee, you can enjoy popular saunas. Furthermore, by visiting just twice a month, you can recoup your investment and have some left over, significantly lowering the perceived cost barrier and encouraging a sauna habit.
2. Simple and Easy-to-Understand Subscription
FLEXKEY is designed with the concept of a "simple subscription" that anyone can use without hesitation. It doesn't require a complicated points system or advance reservations; instead, it offers an easy-to-understand system of unlimited daily visits during low-occupancy hours. There are no facility usage limits, and you can use the sauna once a day for up to 90 minutes during available hours. Unconstrained by conditions or rules, FLEXKEY offers a high degree of freedom, allowing you to enjoy the sauna whenever you want.
3. A Luxurious Facility Lineup
FLEXKEY partners with well-known saunas that everyone has heard of and popular facilities that you'll want to visit regularly. The biggest attraction is the ability to access these "desirable saunas" every day for just a monthly fee. At the time of service launch, affiliated facilities were carefully selected, primarily in Shibuya and Minato Wards, with plans to expand as the number of users grows. We aim to offer a lineup that allows you to continually discover new saunas.
⸻
FLEXKEY is a new sauna-going app that eliminates traditional sauna challenges, such as high prices, crowded, and limited options, by utilizing low-occupancy times. With smart entry and exit, affordable pricing, and an attractive lineup of saunas, FLEXKEY offers the perfect option for making saunas a part of your everyday routine.
FLEXKEY was created to make saunas more accessible and easier to maintain. Simply open the app and scan the facility's QR code to enter and exit. No need to go through the reception process, providing a stress-free, smooth experience. Another great feature is that sauna use is limited to affiliated facilities' "off-peak hours (low-occupancy)," allowing you to enjoy the sauna in peace and quiet while avoiding crowds. It's designed for both those who want to go to the sauna every day and those who want to make it a healthy habit.
⸻
[Key Features]
1. Unbeatable Cost Performance
FLEXKEY allows you to visit the sauna once a day for a monthly fee of ¥4,980 (¥5,478 including tax). If you visit every day, the effective usage fee per visit is just ¥183. For less than the cost of a can of coffee, you can enjoy popular saunas. Furthermore, by visiting just twice a month, you can recoup your investment and have some left over, significantly lowering the perceived cost barrier and encouraging a sauna habit.
2. Simple and Easy-to-Understand Subscription
FLEXKEY is designed with the concept of a "simple subscription" that anyone can use without hesitation. It doesn't require a complicated points system or advance reservations; instead, it offers an easy-to-understand system of unlimited daily visits during low-occupancy hours. There are no facility usage limits, and you can use the sauna once a day for up to 90 minutes during available hours. Unconstrained by conditions or rules, FLEXKEY offers a high degree of freedom, allowing you to enjoy the sauna whenever you want.
3. A Luxurious Facility Lineup
FLEXKEY partners with well-known saunas that everyone has heard of and popular facilities that you'll want to visit regularly. The biggest attraction is the ability to access these "desirable saunas" every day for just a monthly fee. At the time of service launch, affiliated facilities were carefully selected, primarily in Shibuya and Minato Wards, with plans to expand as the number of users grows. We aim to offer a lineup that allows you to continually discover new saunas.
⸻
FLEXKEY is a new sauna-going app that eliminates traditional sauna challenges, such as high prices, crowded, and limited options, by utilizing low-occupancy times. With smart entry and exit, affordable pricing, and an attractive lineup of saunas, FLEXKEY offers the perfect option for making saunas a part of your everyday routine.
Alternatives to FLEXKEY
Looking for apps like FLEXKEY? Here are 6 similar Android apps on Google Play. All of them are free to download.
| App | Rating | Price | Installs | Last updated | Compare |
|---|---|---|---|---|---|
| FLEXKEY | – | Free | 100+ | Mar 14, 2026 | |
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| ActivecareErie | – | Free | 10+ | Mar 11, 2026 | Compare |
| MTS Fit | – | Free | 5+ | – | Compare |
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