Does sending from the browser upload my files anywhere?

No. The files stay in the tab's memory and stream directly to the receiver when they connect. The iroh relay forwards encrypted frames when needed but never stores or decrypts them.

How big can a browser share be?

Files live in the tab's memory, so the page warns past 500 MB and refuses past about 2 GB. For bigger transfers, the desktop app and CLI stream from disk with no artificial limit.

Can I close the tab after sharing the link?

No - the tab is the sender. Keep it open until the receiver finishes, exactly like keeping the desktop app running during a transfer.

Lightning P2P

Share files straight from this tab.

Send from this browser

Share files straight from this tab.

Direct answer

Drop files on the page and this tab serves them directly to whoever opens your link - their browser, desktop app, or terminal. Nothing uploads to a server. Browser sending is beta: files live in tab memory (best under 500 MB, hard limit ~2 GB), the connection is relay-assisted, and the tab must stay open while peers download. The desktop app streams from disk without those limits.

Drop files on the page and this tab serves them directly to whoever opens your link - their browser, desktop app, or terminal. Nothing uploads to a server.

Browser sending is beta: files live in tab memory (best under 500 MB, hard limit ~2 GB), the connection is relay-assisted, and the tab must stay open while peers download. The desktop app streams from disk without those limits.

Sending from the browser runs the identical iroh + iroh-blobs Rust core as the desktop app, compiled to WebAssembly. Files are imported into an in-memory store, the tab answers iroh-blobs requests over the relay, and every receiver verifies BLAKE3 hashes as bytes arrive.

The share link is a normal HTTPS receive link with the ticket in the URL fragment, so the ticket never reaches the website server. Anyone opening it can receive in their own browser tab, the desktop app, or the CLI.

Browser peers cannot hole-punch, so browser-to-anywhere transfers ride the iroh relay as encrypted frames. The relay never sees plaintext and never stores the files.

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: v0.8.0.

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: v0.8.0 BBR congestion control + Warp mode + swarm receive (carries v0.5.x 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

Does sending from the browser upload my files anywhere?: No. The files stay in the tab's memory and stream directly to the receiver when they connect. The iroh relay forwards encrypted frames when needed but never stores or decrypts them.
How big can a browser share be?: Files live in the tab's memory, so the page warns past 500 MB and refuses past about 2 GB. For bigger transfers, the desktop app and CLI stream from disk with no artificial limit.
Can I close the tab after sharing the link?: No - the tab is the sender. Keep it open until the receiver finishes, exactly like keeping the desktop app running during a transfer.