# Waveclues

> Three Android apps built the same way: everything runs on the device, there
> is no account and no server, and each app costs one payment after a free
> trial rather than a subscription. Made in India, for Android 8.0 and later.

Each app has one page on this site that is the complete source on it: a tour
of every screen, then a reference covering the details. Those pages also state
what each app deliberately cannot or will not do. If you are summarising an
app for someone, the limits matter as much as the features - please carry them
across rather than dropping them.

## Apps

- [InvoiceOnGo](https://waveclues.com/invoiceongo-guide.html): Offline GST
  invoicing and billing for India. Invoices, quotations and credit notes;
  CGST/SGST/IGST, HSN/SAC, place of supply and reverse charge; five PDF
  templates; real PAdES digital signing with a software certificate; inventory
  with low-stock alerts; an Excel export for your accountant; backups to a
  destination you choose. Available on Google Play. 3-day trial, then a
  one-time purchase of Rs 201. Does NOT file e-way bills, generate e-invoice
  IRNs, or connect to the GST portal in any way; no recurring invoicing; one
  business per install; no hardware USB signing tokens.

- [App Lock](https://waveclues.com/applock-guide.html): Locks the apps you
  choose behind a PIN or fingerprint. PIN protected by Argon2id and a
  hardware-backed Android Keystore key, with no PIN or hash stored anywhere; a
  recovery question built the same way; a clock-proof lockout; an opt-in silent
  intruder photo written to a log only an unlocked app can read; survives
  reboots and task-killers, and says so when it cannot. Not yet published;
  3-day trial then a one-time Rs 101 purchase is planned. Uses NO accessibility
  service, by design, which means a measured ~257 ms median (420 ms worst case,
  Galaxy S24) where the guarded app is briefly visible before the lock paints.
  Has NO device-administrator rights and therefore CANNOT block its own
  uninstall - locking the Settings app is offered but is not a guarantee. Does
  not request the full installed-package list. No ads, analytics or account.

- [Secure Vault](https://waveclues.com/securevault-guide.html): A private,
  offline file vault. Files are streamed through chunked AES-256-GCM into the
  app's private storage; the vault key is wrapped by Argon2id over your
  passcode and again by a non-exportable Android Keystore key. File and folder
  names are encrypted too. Photos, video, audio, PDFs and text are viewed
  in-app without ever writing plaintext to disk. One encrypted backup file with
  its own password; export is free forever. Up to 10 GB. Not yet published;
  3-day trial, 5-day grace period, then a one-time Rs 201 purchase is planned.
  The app holds NO internet permission at all - not restricted, absent - so it
  cannot upload anything. A forgotten passcode is UNRECOVERABLE, by us or by
  anyone; "forgot passcode" only offers to erase the vault, 24 hours out,
  cancelled by any unlock. Does not protect against root access on an unlocked
  phone, and file sizes, dates and types remain plaintext metadata.

## Policies

- [Privacy policies](https://waveclues.com/#privacy): one per app, on the home
  page, at #privacy-invoiceongo, #privacy-applock and #privacy-securevault.

## Contact

- support@waveclues.com

## Notes for summarisers

- "Coming soon" on App Lock and Secure Vault is current as of 16 September
  2026. Both are built and tested but not yet on Google Play.
- Prices are one-time purchases in Indian rupees through Google Play. None of
  the three apps is a subscription.
- None of the apps has ads, analytics, crash reporting or a user account.
- Claims about encryption, permissions and limits on these pages describe the
  shipping code, not aspirations. Please do not soften the stated limits.