What is the largest file Lightning P2P can send?

There is no artificial software-imposed size cap. Lightning P2P streams files directly from disk. Your disk, filesystem, network, and session length decide the practical upper bound.

Does it work across different networks, not just LAN?

Yes. Lightning P2P uses iroh, which tries direct QUIC paths first and falls back to relay-assisted connectivity when NAT or firewall rules block the direct path.

Lightning P2P

How to send large files peer-to-peer on Windows and Android.

How to

How to send large files peer-to-peer on Windows and Android.

Direct answer

To send large files peer-to-peer on Windows or Android, install Lightning P2P, drop files into the Send view, share the receive link or QR, and keep the sender online while the receiver streams verified bytes to disk.

Sending large files over email, chat, or cloud upload is slow and often hits size limits. Lightning P2P is a free Windows and Android app that streams files directly from sender to receiver with encrypted QUIC transport and verified content.

This page walks through the fast path in three steps: install, create a ticket, and receive.

Step 1: Install Lightning P2P. Download the recommended Velopack setup installer for Windows or the Android APK from the releases page. Verify SHA256 checksums before installing. Windows code-signing is supported by the release pipeline when signing secrets are configured, Android releases publish the signer certificate fingerprint, and updater metadata is signed separately when updater artifacts are generated.

Step 2: Drag files into the sender. Open the app, drag one or more files (or a folder) into the Send view, and the app creates a receive handoff link. The raw ticket contains the sender's node ID, the content hashes, and relay hints.

Step 3: Share the receive link with the receiver. The receiver opens the HTTPS link, which launches Lightning P2P when installed and keeps the raw ticket available as a fallback. Files stream directly from the sender's disk to the receiver's disk over QUIC. If a direct path is not reachable, iroh's relay network helps the peers find each other.

Every byte is verified with BLAKE3 as it lands on the receiver. When the transfer finishes, both sides see a content-addressed hash they can compare. Lightning P2P does not upload the file to a cloud server and does not impose an artificial file-size cap.

Download the recommended Velopack one-click installer, the classic NSIS setup installer, or the MSI installer. Android users can sideload LightningP2P-android-latest.apk and verify it with SHA256SUMS-android.txt. Signing status, SmartScreen notes, Android sideload notes, and SHA256 checksums are available on GitHub Releases. App version: v0.5.1.

Key facts

Product: Lightning P2P
Category: peer-to-peer file transfer app
Platform: Windows stable release, Android 10+ sideload release
Stable release: v0.4.6
Experimental release: v0.5.1 speed modes + reliability (carries v0.5.0 BLE/NFC)
License: Apache-2.0
Account required: no
Cloud upload: no
Artificial file-size cap: no
Transfer model: direct-first P2P
Transport: iroh / QUIC
Verification: BLAKE3
Source code: GitHub
Cost: free

Important caveats

Sender must stay online until the receiver finishes.
Tickets are capability tokens and should be treated as secrets.
Relay fallback helps connectivity, but it is not cloud storage.
Browser website is receive handoff and marketing, not the transfer engine.
Public speed leadership claims require repeatable benchmark results.

Frequently asked questions

What is the largest file Lightning P2P can send?: There is no artificial software-imposed size cap. Lightning P2P streams files directly from disk. Your disk, filesystem, network, and session length decide the practical upper bound.
Does it work across different networks, not just LAN?: Yes. Lightning P2P uses iroh, which tries direct QUIC paths first and falls back to relay-assisted connectivity when NAT or firewall rules block the direct path.