Badminton training app — privacy, terms, medical disclaimer and support.
The short version.
Vakka is fully usable without an account. If you do not sign in, your training log, test results and notes stay on your device only.
If you choose to sign in, they are backed up to a server so you do not lose them when you change phones — and you can delete that entire copy from inside the app.
The only thing that leaves your device without you choosing it is an anonymous crash report when the app fails — with no name, no email and none of your training data.
Vakka requires no registration. Install it and every feature works: prescribed sessions, level testing, the log, the knowledge library. We ask for no name, phone number or other personal detail to get you started.
The app stores the following in its own private storage, on your device:
If you do not sign in, none of this leaves your device. There is no cloud copy, and nobody — including us — can read it.
The consequence worth knowing: uninstalling the app deletes everything. There is no way to recover it, because no copy exists anywhere else. Data does not follow you to a new phone. That is exactly why the next section exists.
Signing in is optional, and it does exactly one thing: it keeps your data when you change or lose a phone. No feature is locked behind it.
We do not receive your name, profile photo, contacts or anything else from your Apple/Google account.
Exactly the five groups listed above: sessions, test results, commitments, situation answers, and your settings and level profile. Nothing more.
On Supabase infrastructure hosted in Singapore. Each account can read and write only its own rows — enforced in the database itself through row level security, not by software running on your phone.
In the app: Settings → Account & sync → Delete account. This permanently removes the account and the entire server-side copy. The copy on your phone is untouched, and the app keeps working in full.
If you only want to stop backing up while keeping the account, tap Sign out — no new data is sent from that point on.
When the app hits an error and stops unexpectedly, a technical report is sent to Sentry so we can fix it. It is the only thing that leaves your device without you choosing it.
| The report DOES contain | The report does NOT contain |
|---|---|
|
The line of code where the failure occurred Device model and operating system version App version Which screens you passed through before the failure |
Name, email, phone number Training log or test results Personal identifiers or an IP address tied to you Anything you typed into the app |
We enable sendDefaultPii: false, which means Sentry does not attach personally identifying information to reports. Sentry is operated by Functional Software, Inc. (United States), so crash reports are processed outside Vietnam. Reports are used only to fix defects — never for advertising or behavioural analytics.
Two companies come into technical contact with the data, and each does exactly one job on our behalf — neither may use it for their own purposes: Supabase stores the backup if you sign in, and Sentry receives crash reports. Beyond those two names, nobody.
If you have not signed in: the data lives on your device and you control it completely — delete it inside the app, or uninstall the app to remove all of it. We hold no copy to hand over or erase on your behalf.
If you have signed in:
All three work inside the app and do not depend on us answering an email. For anything else, write to us at the address in the Support section.
For crash reports: if you want one deleted, write to us with the date, time and device model and we will locate and remove the corresponding record.
Vakka is not directed at children under 13 and does not knowingly collect data from them. Minors should use the app under adult supervision, particularly the physical conditioning exercises.
If this policy changes, the date at the foot of this page changes with it. Material changes will be noted in the release notes on the app stores.
Vakka is provided free of charge for personal use. You may use the app and its content to train yourself and to guide the people you play with.
The exercises, programmes, diagrams, images and knowledge content in the app belong to the author. You may not copy, redistribute, sell or incorporate them into another commercial product without written permission.
The content was written in the author's own words, drawing on coaching experience and publicly available sources. Training ideas and methods belong to nobody; the particular expression of them in this app belongs to the author.
The app is provided “as is”. We try to get it right, but we do not warrant that it will run without defects or interruption, or that it suits your particular purpose.
Specifically and importantly: the timer and audio cues depend on the operating system. iOS and Android may suspend a backgrounded app or withhold notifications depending on your device settings, battery-saving mode and the permissions you granted. Do not rely on Vakka as your only timing device where a missed cue would matter.
To the extent permitted by law, we are not liable for damages arising from use of the app — including training injuries, data loss, or a cue that fails to sound at the right moment.
These terms are governed by the laws of Vietnam.
Vakka prescribes physical exercise and discusses injuries. It is not medical advice.
The app is not a substitute for a doctor, a physiotherapist or a qualified coach. Do not use it to diagnose or treat any health condition.
Sharp pain, dizziness, nausea, breathlessness, chest tightness, or joint pain that worsens during a session. Pain that builds in the days after a session is also a signal to stop and seek medical advice.
Vakka lets you mark a current injury and will avoid exercises that load that area. This is a convenience for filtering exercises, not a medical assessment. It does not know your specific condition, does not replace a diagnosis, and does not guarantee that the remaining exercises are safe for you.
The level thresholds in the app are currently provisional figures, drawn from coaching experience rather than validated against a large sample. Treat an assessment result as a starting point for comparing yourself against yourself over time, not as an accurate measure of your standard.
You train at your own risk. When in doubt, ask a qualified professional first.
Found a bug, have a suggestion, or want to ask about the app — write to:
The app is built by one person, so a reply may take a few days. Vietnamese or English are both fine.