?? Orka!


README is not correct. WIP Orka is renewal version of Localdrop!

LocalDrop is peer to peer LAN(Local Area Network) data sharing service.


link : https://localdrop.me

Mobile version

(You can scroll horizontally)


? In home and office, sometimes I need to transfer data (text or file) from device1 to device2. It would be easy if sharing app (google drive, dropbox, etc) is installed in both devices. But most of time, it is not. So I decided to make my own sharing service. The reason to make this by myself is because it would be fun and I can customize whatever I want. Plus, I haven’t used webRTC and webSocket before, it’s good chance to practice those apis! That’s why I made LocalDrop.

How to use

? Each browser has its own UUID. If other peer joined then, it will be appeared in PEERS: tab.

Important!: To use download feature, Turn off Update on reload in chrome devTools – Application – Service Workers section. To avoid memory issue for large file transfer, LocalDrop uses StreamSaver.js. It ingeniously solves memory issue using iframe + service worker. Because it utilizes service worker heavily, we need to turn Update on reload option off.

Sending data

You can send text or any kind of data.

Sending Text

? To send Text, you need to click other peer to send and type text. Then click send button!

Sending File

? To send File, click red cross button then select files to transfer. Important!: After you select files, it does not transfer immediately. It just gives download link to other peer. When other peer requests download, then transfer starts.

Check system message

When there is something to notify to user, system message is created. You can check system message by clicking toggle switch!

Change color theme

? Change color theme as you want! Click Change Color theme button to change color! Default is MaterialThemeOcean. Why? I like this ? Currently (13:32 Wed 01 Jul 2020) it support 13 color themes. Here is the list

  • MaterialThemeOceanic
  • MaterialThemePalenight
  • MaterialThemeDarker
  • MaterialThemeDeepOcean
  • ThemeOneLight
  • ThemeMonoKaiPro
  • MaterialThemeLighter
  • SolarizedLight
  • ThemeDracula
  • ThemeArcDark
  • ThemeOneDark
  • ThemeNightOwl
  • ThemeLightOwl

Self Hosting

?️ Because webRTC needs to transfer offer and answer between peers, there is signaling server outside of LAN. If you want to host signaling server by yourself. Follow these steps.

  • clone this repository

client side

// in the repository,
$ cd client
$ npm run dev

signal server side

// in the repository,
$ cd signaling-server
$ npm run dev

Change url as you want!

Many urls are from .env.development file. Customize yourself

// File: .env.development



? Current version is v0.1.0. There are lots of things to do. Here’s TODO list

  • Remove chunk header (It causes slow down download speed)
  • Create dataChannel everytime download request (to support parallel download)
  • Better UX for mobile view..
  • Notify system message via toast or notification
  • Display download progress for transfer side
  • Handle peerConnection recreate
  • Handle webSocket recreate
  • Make docker image to support cross flatform self hosting
  • Make Logo icons
  • Handle ping/pong based on visibility change


? Because I use chromium, chrome and samsung browser, I tested those and it seems LocalDrop runs smoothly.

Self QnA

? This section is self QnA.

Why Browser Compatibility is limited?

Because I made this to use by myself, I haven’t tested on Opera and Firefox. One thing for sure is that Localdrop can not support ios Safari and Safari.

LocalDrop not works in my environment X(

Sadly, there are several reasons I guess. In my case, I have experienced this situation in StarBucks. I guess if router blocks sending data to local peer, this could be happened.

? About download speed

Why LocalDrop sends chunk with header?

Currently, LocalDrop sends chunk with header to classify where does chunk from. Putting and parsing header has some overhead. If header is removed, then speed would be faster 2 times (I’ve tested).

Why do we care about BufferControl?

Depends on your device (pc or mobile) and network environment, buffer control is needed. In chromium, buffer size is 16 Mb for now, 14:07 Wed 01 Jul 2020. (https://chromium.googlesource.com/external/webrtc/+/master/pc/data_channel.cc) If buffer is overflowed in sending side, dataChannel got error Unable to queue data for sending.

So I set buffer limit as half of chromium limitation (8 Mb). Hence, because of buffer control, download speed varies a bit.

? Why DataChannel Chunk size is 16k?

RTCDataChannel.send() has some limitation. Some people recommends to send around 16kiB at most. I referred these links

? Memory Issue about Transfer Large file: Why does LocalDrop use StreamSaver.js?

When transferring large file, we need to care about memory in receiver side. If we just accumulate chunks in memory, device would be crashed easily. I’ve tested and if you have enough swap space, then accumulated chunks are goes into swap area. It’s okay for desktop, but not for mobile.

We can use filesystem API but it is deprecated. That’s why I use StreamSaver.js to avoid memory issue.




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