DropLink LocalSend
LocalSend is a popular open-source LAN file-sharing app. DropLink covers the same ground — fast, encrypted local transfer — and adds internet P2P with NAT traversal, a built-in Web UI, and QUIC transport.
Quick answer
DropLink and LocalSend both deliver fast LAN transfers, but DropLink adds three things LocalSend cannot do: internet P2P with NAT traversal (via iroh), a built-in Web UI so the receiver does not need any app, and QUIC transport with BBR congestion control (vs LocalSend's HTTP over TCP). On a gigabit LAN both are fast; on lossy Wi-Fi or cross-network scenarios DropLink is significantly more robust. LocalSend is fully open source; DropLink's transport protocols (QUIC, Noise, BLAKE3) are open but the app itself is not yet open-sourced.
Feature matrix
| Feature | DropLink | LocalSend |
|---|---|---|
| Local network (LAN) transfer | ||
| Internet P2P transfer | ||
| NAT traversal | ||
| Web UI — receive via browser | ||
| Native macOS app | ||
| Native iOS app | Coming soon | |
| Native Windows app | ||
| QUIC transport | ||
| End-to-end encryption | ||
| Password protection | ||
| AirDrop-style requests | ||
| Open source | ||
| Price | Free | Free |
Should you switch to DropLink?
LocalSend is an excellent open-source choice if your use case is strictly local network. DropLink is the better pick if you need internet transfers, want receivers to use just a browser, or value QUIC's performance on modern networks.
Common questions
What does DropLink offer that LocalSend does not?
DropLink supports internet transfers with NAT traversal — LocalSend only works on the same local network. DropLink also has a built-in Web UI, so the receiver does not need any app installed. And it uses QUIC for faster, more reliable transfers on modern networks.
Is LocalSend faster than DropLink?
On the same local network, speeds are comparable. However, DropLink uses QUIC which has a 1-RTT handshake vs HTTP/TCP used by LocalSend. For small files and high-latency networks, DropLink is noticeably faster.
Can I use DropLink offline like LocalSend?
Yes. DropLink works on local networks without an internet connection — the same as LocalSend. The internet is only used when transferring files between devices on different networks.
DropLink vs LocalSend — what is actually different
Transport: QUIC vs HTTP over TCP
LocalSend uses plain HTTP over TCP for file transfer. TCP suffers from head-of-line blocking (one lost packet stalls the whole stream) and needs separate TLS handshakes (2-3 RTT). DropLink uses QUIC (RFC 9000) via quinn 0.11: built-in TLS 1.3, stream multiplexing without HOL blocking, 1-RTT handshake (0-RTT on resume). On Wi-Fi with occasional packet loss, QUIC is noticeably more resilient.
Internet P2P with NAT traversal
LocalSend only works between devices on the same local network. DropLink adds a second path: when devices are on different networks, it uses iroh 0.96 for NAT hole-punching, with a DERP (Designated Encrypted Relay for Packets) relay as fallback. The iroh public DNS discovery is explicitly disabled — only the DropLink-operated relay is used, so the device IP is not published to third-party DNS servers.
Web UI — receiver without any app
DropLink includes an embedded HTTP server (axum on the Rust core) that exposes a local Web UI. The receiver opens a link in any browser and downloads files — no app, no account. For remote receivers, the relay server runs a gateway that proxies iroh blobs as HTTP responses. LocalSend requires both sides to have the LocalSend app installed.
Discovery and performance details
Both apps use mDNS for discovery, but DropLink publishes the QUIC certificate fingerprint in the TXT record for TOFU verification. DropLink's LAN transport uses 8 MB UDP socket buffers, initial MTU 1472 with 1200 fallback, 64 MB stream receive window, BBR congestion control with 1 MB initial window, and ACK frequency reduced to every 10 packets or 5 ms — tuned specifically for Wi-Fi 6. Typical LAN speed is 50+ MB/s.
Security differences
Both apps use TLS for transport security. LocalSend uses self-signed certificates with a visual trust prompt. DropLink uses TLS 1.3 (TLS 1.2 rejected) over QUIC with ECDSA P-256 certificates and Trust On First Use via mDNS fingerprint — no prompts after the first pairing on a given network. Cipher suites are architecture-optimized (AES-NI on x86, ChaCha20-Poly1305 on ARM). For internet transfers, DropLink adds the Noise protocol (IK handshake, ed25519 identity) and BLAKE3 verified streaming: even a malicious relay cannot alter bytes without detection.
Performance comparison
- DropLink LAN speed
- 50+ MB/s on Wi-Fi 5/6
- DropLink handshake
- 1 RTT (0-RTT resume)
- LocalSend handshake
- TCP + TLS (2-3 RTT)
- Congestion control
- BBR vs stock TCP
- Head-of-line blocking
- No (QUIC) vs Yes (TCP)
- Internet transfer
- DropLink: yes (iroh + DERP). LocalSend: no.
Technical FAQ
Is DropLink open source like LocalSend?
The underlying protocols DropLink uses (QUIC, TLS 1.3, Noise, BLAKE3, mDNS) are all open standards. The app itself is not yet open source — DropLink is currently distributed as a free, closed-source app on the App Store and Microsoft Store. LocalSend, in contrast, is fully open source under an MIT-like license.
Why use QUIC instead of HTTP for file transfer?
QUIC eliminates head-of-line blocking (a lost packet does not stall the whole stream), reduces handshake time to 1 RTT (0-RTT on resume), and integrates TLS 1.3 natively. On a LAN with occasional Wi-Fi drops, QUIC is visibly more resilient than HTTP over TCP. DropLink tunes QUIC specifically for LAN: 8 MB UDP buffers, 64 MB stream window, BBR with 1 MB initial window, ACK frequency reduced to every 10 packets.
Can I use DropLink without installing anything on the receiver?
Yes. The Web UI is the killer feature here. The sender runs DropLink, which starts a local HTTP server and a signaling session on the relay. The receiver opens the generated link in any browser (iPhone, Android, Linux, anything) — no app needed. LocalSend always needs its app on both sides.
What happens when I leave the local network?
LocalSend cannot transfer anymore. DropLink transitions to internet P2P via iroh: it first attempts NAT hole-punching to establish a direct QUIC connection between the two devices, and only if that fails does it fall back to the DERP relay. Either way, the transfer is end-to-end encrypted and the relay never sees the file content.