Files are encrypted in your browser using AES-GCM before being uploaded. The decryption key never touches the internet - it travels purely as a sound wave. If you're not physically in the room to hear it, you can't decrypt the file.
Does the server see my files?
No. The server is a blind relay - it holds only encrypted ciphertext. The key is transmitted via sound, so the server has no way to read your files.
How long do files persist?
By default, chirpfile is burn-after-read. The encrypted blob is deleted immediately after the first download. Unclaimed files expire after 15 minutes regardless.
Connectivity & Hardware
Do I need to be on the same WiFi?
No. Unlike AirDrop or LocalSend, chirpfile doesn't rely on local network discovery. Your laptop can be on corporate WiFi and your phone on cellular - as long as both devices have internet and can hear each other, it works.
What if the room is noisy?
Switch from the default Silent (ultrasound) mode to Audible mode. It uses a faint audible chirp that's more resilient to background noise.
What range does it need?
Under 1 meter in Ultrasound mode, a few meters in Audible mode. Both devices need to be in the same room with speakers and mic unobstructed.
Why does it need microphone access?
The microphone is how the receiving device hears the decryption key. Without it, there's no way to receive the chirp. chirpfile doesn't record or store any audio - the mic input is processed in real-time to decode the key, then discarded.
Limits & Pro
What are the file size limits?
Free tier: up to 15 MB. Pro: up to 1 GB, with batch transfer (auto-zip multiple files).
What is Persistent Mode?
A Pro feature. Instead of deleting after the first download, the file stays available for 15 minutes - useful when multiple devices need to receive the same file from a single chirp.