Tutorials · 5 min read

Loom application

Building "Loom" in the browser: record a video with api.video

Building a video recording app like Loom - in the browser! Share your camera and screen, and get a shareable link to your video. Not only is it possible, but we added live streaming as well!

Doug Sillars

March 26, 2021

With the explosive growth of remote working in the past year, we’ve all worked to find different ways of communicating. Slack and Zoom have become major tools for communication as we are all no longer in the same building or office.

Apps like Clubhouse have become ‘places’ to go and hang out and chat with others.

One app that has featured explosive growth over the past year is Loom. Loom is an app that lets you record short video messages - sharing your screen or just using your camera. When you are done, the video is saved on a server, and you are given a link. This link is easy to share: on social media, on Slack etc. It is a great way to communicate an idea, or to express your point - it’s everything that is great about video, packaged in an easy to use interface.

It is no wonder that Loom is so successful. My only issue is that I either have to use an installed app on my Mac (265 MB installed), or a Chrome extension (I did not go this approach, as Chrome eats too much memory already).

Can I build a Loom-like app - in the browser?

I lead developer relations at api.video. We offer a full service API for video transcoding, hosting and delivering video streams. It is incredibly fast, and can be used to share videos in the same way Loom does. So this raised 2 questions:

  1. If I delegate the ‘hard’ bits of the video handling to api.video, can I build a recording app in the browser?

  2. Can I get this app running in all four major modern browsers? Desktop & mobile?


Question 1: Yes - you can build a website to record and share video (screen sharing and camera video). It will even stream live video!

Question 2: Almost all browsers. On the desktop, the full featured app works great in Chrome, Edge Firefox, and Safari 14.0.3 (there are some support issues that will fail below Safari 14).

For Mobile: it works on Android (without screen sharing). Unfortunately, the APIs used are not yet in mobile Webkit, so no iOS support at this time.

Try it out! The application is live at record.a.video. You can also check out our live stream API reference documentation.

How does it work?

record.a.video menu

When you open record.a.video, you'll get a menu as above. (You may not get the available cameras and microphones - press "start capture" and allow camera/microphone permissions, then reload the page).

  • The top bar allows you to switch between Live streaming and recording a video.
  • Choose your camera and mic (if you have more than one).
  • Select the screen layout - do you want to show just the camera or screen, or do you want to overlay the camera on the screen?
  • Live captions: If you are using Chrome, we can add live captions to the video being created. Pick top or bottom for the captions.
  • "Show recording" if you leave this checked, you'll see the video being recorded in the browser. Our CEO dislikes the "vortex effect" you see when sharing the screen, so we added this button for him to disable the view. (👋 Hi Cedric!)

Now that you've chosen all your options, you're ready to start capture!


Once you've started recording, you'll see 3 new views appear:

  • The screen being shared
  • The camera
  • The recording (showing screen, camera or both). (Unless you hid the recording).
recording video

We made a video of the whole process:

record a video demo

Record and stream right from your browser!

So it works! Recording your screen and camera in the browser with live streaming or recording and uploading for asynchronous viewing.

What completely blows my mind about this application is that leveraging web APIs, this site weighs in at just under 300KB. There is a NodeJS backend to handle the streaming (we have to convert the format to RTMP for ingestion into api.video), but if you remove the live streaming component, this app runs with just JavaScript (you can even run it locally on your computer!)

See it in action

Curious about the details

I'm really glad you asked! We've written a series of posts describing the APIs used to collect video streams, how they were cpmbined, and how they are streamed:

  • In post 1, I talked about the getUserMedia API to record the user's camera and microphone.

  • In post 2, I discussed recording the screen, using the Screen Capture API. Using the video streams created in posts 1 & 2, I draw the combined video on a canvas.

  • In post 3, I'll discuss the MediaRecorder API, where I create a video stream from the canvas to create the output video. This output stream feeds into the video upload (for video on demand playback) or the live stream (for immediate and live playback).

  • In post 4, I'll discuss the Web Speech API. This API converts audio into text in near real time, allowing to create 'instant' captions for any video being created in the app. This is an experimental API that only works in Chrome, but was so neat, I included it in record.a.video anyway.


Record.a.video lets you easily record and share video - live or asynchronously!

Go give it a shot record.a.video, and if you want to build your own - the code is on Github. In the coming days, we’ll add some technical posts describing how we built it.

If you have any comments or suggestions, please leave us a note in our community forum.

Try out more than 80 features for free

Access all the features for as long as you need.
No commitment or credit card required

Video API, simplified

Fully customizable API to manage everything video. From encoding to delivery, in minutes.

Built for Speed

The fastest video encoding platform. Serve your users globally with 140+ points of presence. 

Let end-users upload videos

Finally, an API that allows your end-users to upload videos and start live streams in a few clicks.


Volume discounts and usage-based pricing to ensure you don’t exceed your budget.