Recordings that prove themselves.
HearSeal seals your recording and has external services sign it. Any later change is always detected, so anyone who receives it can check, for free, that it has not been edited.
How it works
Harassment, violence, disputes over what was said. A recording helps a lot, but it can be challenged as “edited”. HearSeal attaches proof to the recording itself.
Sealed as you record
Just record as usual; it is sealed as you record. Removing, reordering or adding any part is detected. If the app stops, everything up to that point is kept.
Signed by external services
External services — not you, not us — sign the seal. Rewriting it later, or faking when it was recorded, is caught by verification. The audio itself is never sent.
Stored only in your own cloud
Recordings stay on your phone and in your own Google Drive or Dropbox; in evidence mode they upload even while recording. The developer never receives them.
Anyone can verify, for free
Police or lawyers just drop the files on the verification page. Everything happens in the browser; nothing is uploaded. No need to trust the developer.
What is proven — and what is not
HearSeal is not “perfect tamper-proofing”. We are honest about what it can and cannot prove.
Proven
- The audio and its records have not changed since they were made on the device
- It was recorded within the time range vouched for by external services
- Where it was interrupted (calls, the system, the app stopping)
Not proven
- That the sound was a real conversation (audio played from a speaker cannot be told apart)
- That the phone's clock itself was right
- That the location is more accurate than the OS reported
- That transcripts and AI summaries are correct (they are reference only)
Whether you may record depends on local law. HearSeal does not give legal advice. Using it to secretly record or spread sexual acts is prohibited.
How to use
Getting started.
- Connect your storageIn Settings → Storage, connect Google Drive or Dropbox so recordings survive losing your phone.
- RecordJust tap. You can also start without looking from a home-screen shortcut, a Quick Settings tile or a widget. Recording continues when you leave the app.
- Use “evidence mode” when it mattersRecords continuously with the built-in mic only, gets signatures frequently while people talk, and uploads right away.
- Listen and searchSearch the on-device transcripts and play from that point. Mark important moments and add notes.
- Hand overOpen a recording, tap “Export”, save the range you need as an evidence package (.zip), and give it directly to the police or a lawyer. Location and notes are included only if you choose.
- Have it verifiedThe recipient just drops the files on the verification page. Files from the HearSeal storage folder can be checked as they are, too.
Privacy
We never receive your recordings
Audio, transcripts and notes stay on your phone and in your cloud. Only a value that reveals nothing about the recording is sent to external services for signing.
No hiding features
The OS microphone indicator and the recording notification stay. You can choose a discreet icon and notification, but the app is never hidden (so it cannot become stalkerware).
Open verification
The verification method and verifiers are published. Anyone can check independently, without trusting the developer.
Getting help
You are not alone. If you are in danger, call your local emergency number.
Outside Japan, please contact your local police or victim support services.
FAQ
Does it use a blockchain?
No. No cryptocurrency is involved either.
Can it record phone calls?
No. Because of OS restrictions it pauses during calls (including internet calls). The paused time is recorded and shown in the verification result.
Google Drive shows the recording as 0 seconds
Evidence audio is stored in a format that survives interruptions, so some previews show no length. Open the “.play.m4a” playback copy next to it. Verification uses the original file.
Are files sent anywhere when I use the verification page?
No. Verification runs only in your browser, and the page is configured to block all outgoing connections. It also works offline.
Is there an iPhone version?
It is in preparation. The Android version comes first.