Common questions about security, connectivity, and Pro features.
How secure is the transfer?
Files are encrypted in your browser using AES-GCM (Web Crypto API) before being uploaded. The decryption key never touches the internet — it is transmitted purely as a physical sound wave. If an attacker isn't physically present to hear the chirp, they cannot unlock your data.
Does the server see my files?
No. The server acts as a blind relay — it receives only encrypted ciphertext. Because the decryption key is only transmitted via sound, the server has no way to read your files.
How long do files persist?
By default chirpfile is burn-after-reading. Encrypted blobs are deleted from the relay immediately after the first successful download. All data expires after 15 minutes regardless of download status.
Do I need to be on the same Wi-Fi?
No. Unlike AirDrop or Snapdrop, we don't rely on local network discovery. Your laptop can be on corporate Wi-Fi and your phone on 5G — as long as the devices can hear each other, the transfer works.
What if the room is noisy?
If the default Silent (ultrasound) mode fails, switch to Audible mode in the settings. It uses a standard audible data-chirp that is more resilient to background noise and echo.
What range does it need?
Practical decode range is under 1 meter in Ultrasound mode, and a few meters in Audible mode. Both devices need to be in the same room with speakers and mic unobstructed.
What are the file size limits?
The Free tier supports files up to 15 MB. Pro increases this to 1 GB, suitable for large documents, videos, and archives.
What is Persistent Mode?
Available for Pro users. Instead of deleting after the first download, Persistent Mode keeps the file available for 15 minutes — useful when multiple devices in a room need to receive the same file after a single chirp.