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Note: This README applies to development branch. See the version for the latest stable release here.

asciinema player

Build status

Web player for terminal sessions (recorded with asciinema) you can use on your website.


asciinema player is an open-source terminal session player written in Javascript and Rust. Unlike other video players asciinema player doesn't play heavy-weight video files (.mp4, .webm etc) and instead plays light-weight terminal session files called asciicasts.

Asciicast is a capture of terminal's raw output, which needs to be interpreted during playback, therefore the player comes with its own interpreter based on Paul Williams' parser for ANSI-compatible video terminals. It's fully compatible with most widely used terminal emulators like xterm, Gnome Terminal, iTerm etc.

You can see the player in action on

If you don't want to depend on and you prefer to host the player and the recordings yourself then read on, it's very simple.


Quick start

The following examples show how to use asciinema player on your own website.

It assumes you have obtained terminal session recording file by either:

Use standalone player bundle in your HTML page

Download latest version of the player bundle from releases page. You only need asciinema-player.min.js and asciinema-player.css files.

First, add asciinema-player.min.js, asciinema-player.cssand the .cast file of your recording to your site's assets. The HTML snippet below assumes they're in the web server's root directory.

Then add necessary includes to your HTML document and initialize the player inside an empty <div> element:

  <link rel="stylesheet" type="text/css" href="/asciinema-player.css" />
  <div id="demo"></div>
  <script src="/asciinema-player.min.js"></script>
    AsciinemaPlayer.create('/demo.cast', document.getElementById('demo'));

Use the player in your own application bundle

Add asciinema-player to your devDependencies:

npm install --save-dev asciinema-player@3.0.1

Add empty <div id="demo"></div> element to your page to contain the player.

Import and use create function from asciinema-player module:

import * as AsciinemaPlayer from 'asciinema-player';
AsciinemaPlayer.create('/demo.cast', document.getElementById('demo'));

Finally, include player's CSS file in your site CSS bundle. You'll find it in the npm package at dist/bundle/asciinema-player.css.

Basic usage

To mount the player on your page use the create function exported by the asciinema-player ES module with 2 arguments: the URL (or path) to the asciicast file and the container DOM element to mount the player in.

AsciinemaPlayer.create(url, containerElement);

You can tweak file fetching by passing { url: "...", fetchOpts: { ... } } as the 1st argument to create. fetchOpts object is then passed to fetch (as its 2nd argument). This can be used to change HTTP method, configure credentials, etc.

If you'd like to inline the recording contents you can do so with Data URLs. For example:


See Source for more ways of loading a recording into the player.

To pass additional options when mounting the player use 3 argument variant:

AsciinemaPlayer.create(url, containerElement, opts);

For example, enable looping and select Solarized Dark theme:

AsciinemaPlayer.create('/demo.cast', document.getElementById('demo'), {
  loop: true,
  theme: 'solarized-dark'

See Options for full list of available options.

If you'd like to control the player programatically then you can use the functions exposed on the object returned from create function:

const player = AsciinemaPlayer.create(url, containerElement);;

See API for details.


In the most common case the recording to be played is fetched from a URL. If you'd like to load it from a different source you can pass it to create as { data: data } where data can be one of:

  • a string containing asciicast in v1 or v2 format
  • an object representing asciicast in v1 format
  • an array representing asciicast in v2 format
  • a function which when invoked returns any of the above (may be async)

For example:

AsciinemaPlayer.create({ data: data }, containerElement);

data value is defined in one of the following ways:

// object representing asciicast in v1 format
{version: 1, width: 80, height: 24, stdout: [[1.0, "hello "], [1.0, "world!"]]};
// string representing asciicast in v1 format (json)
'{"version": 1, "width": 80, "height": 24, "stdout": [[1.0, "hello "], [1.0, "world!"]]}';
// array representing asciicast in v2 format
  {version: 2, width: 80, height: 24},
  [1.0, "o", "hello "],
  [2.0, "o", "world!"]
// string representing asciicast in v2 format (ndjson)
'{"version": 2, "width": 80, "height": 24}\n[1.0, "o", "hello "]\n[2.0, "o", "world!"]';
// function returning a string representing asciicast in v2 format (ndjson)
() => '{"version": 2, "width": 80, "height": 24}\n[1.0, "o", "hello "]\n[2.0, "o", "world!"]';

If data is a function then the player invokes the function when playback is started by a user. If preload: true option is used then the function is invoked during player initialization.


The following options can be used to tweak player's look and feel:


Type: number

Number of columns of player's terminal.

When not set it defaults to 80 (until asciicast gets loaded) and to terminal width saved in the asciicast file (after it gets loaded).

It's recommended to set it to the same value as in asciicast file to prevent player to resize itself from 80x24 to the actual dimensions of the asciicast when it gets loaded.


Type: number

Number of lines of player's terminal.

When not set it defaults to 24 (until asciicast gets loaded) and to terminal height saved in the asciicast file (after it gets loaded).

Same recommendation as for cols applies here.


Type: boolean

Set this option to true if playback should start automatically.

Defaults to false - no auto play.


Type: boolean

Set this option to true if the recording should be preloaded on player's initialization.

Defaults to false - no preload.


Type: boolean or number

Set this option to either true or a number if playback should be looped. When set to a number (e.g. 3) then the recording will be re-played given number of times and stopped after that.

Defaults to false - no looping.


Type: number or string

Start playback at a given time.

Supported formats:

  • 123 (number of seconds)
  • "2:03" ("mm:ss")
  • "1:02:03" ("hh:mm:ss")

Defaults to 0.


Type: number

Playback speed. The value of 2 means 2x faster.

Defaults to 1 - normal speed.


Type: number

Limit terminal inactivity to a given number of seconds.

For example, when set to 2 any inactivity longer than 2 seconds will be "compressed" to 2 seconds.

Defaults to:

  • idle_time_limit from asciicast header (saved when passing -i <sec> to asciinema rec),
  • no limit, when it was not specified at the time of recording.


Type: string

Terminal color theme.

One of:

  • "asciinema"
  • "monokai"
  • "tango"
  • "solarized-dark"
  • "solarized-light"

Defaults to "asciinema".

You can also use a custom theme.


Type: string

Poster (a preview frame) to display until the playback is started.

The following poster specifications are supported:

The easiest way of specifying a poster is to use NPT format. For example, npt:1:23 will preload the recording and display terminal contents at 1 min 23 sec.


AsciinemaPlayer.create('/demo.cast', document.getElementById('demo'), {
  poster: 'npt:1:23'

Alternatively, a poster value of data:text/plain,This will be printed as poster\n\rThis in second line will display arbitrary text. All ANSI escape codes can be used to add color and move the cursor around to produce good looking poster.

Example of using custom text poster with control sequences (aka escape codes):

AsciinemaPlayer.create('/demo.cast', document.getElementById('demo'), {
  poster: "data:text/plain,I'm regular \x1b[1;32mI'm bold green\x1b[3BI'm 3 lines down"

Defaults to blank terminal or, when startAt is specified, to screen contents at time specified by startAt.


Type: string

Controls the player's fitting (sizing) behaviour inside its container element.

Possible values:

  • "width" - scale to full width of the container
  • "height" - scale to full height of the container (requires the container element to have fixed height)
  • "both" - scale to either full width or height, maximizing usage of available space (requires the container element to have fixed height)
  • false / "none" - don't scale, use fixed size font (also see fontSize option below)

Defaults to "width".

Version 2.x of the player supported only the behaviour represented by the false value. If you're upgrading from v2 to v3 and want to preserve the sizing behaviour then include fit: false option.


Type: string

Size of the terminal font.

Possible values:

  • "small"
  • "medium"
  • "big"
  • any valid CSS font-size value, e.g. "15px"

Defaults to "small".

This option is effective only when fit: false option is specified as well (see above).


Type: string

Terminal font-family override.

Use any valid CSS font-family value, e.g "'JetBrains Mono', Consolas, Menlo, 'Bitstream Vera Sans Mono', monospace".


Type: number

Terminal line height override.

The value is relative to the font size (like em unit in CSS). For example a value of 1 makes the line height equal to the font size, leaving no space between lines. A value of 2 makes it double the font size, etc.

Defaults to 1.33333333.


import * as AsciinemaPlayer from 'asciinema-player';
// skip the above import when using standalone player bundle

const player = AsciinemaPlayer.create(url, containerElement);

The object returned by create function (saved as player const above) contains several functions that can be used to control the player from your code.

For example, initiate playback and print the recording duration when it starts: => {
  console.log(`started! duration: ${player.getDuration()}`);

The following functions are available on the player object:


Returns the current playback time in seconds.

player.getCurrentTime(); // => 1.23


Returns the length of the recording in seconds, or null if the recording is not loaded yet.

player.getDuration(); // => 123.45


Initiates playback of the recording. If the recording hasn't been preloaded then it's loaded, and playback is started.;

This function returns a promise which is fulfilled when the playback actually starts. => {
  console.log(`started! duration: ${player.getDuration()}`);

If you want to synchronize asciinema player with other elements on the page (for example <audio> element) then you can use this promise for coordination. Alternatively you can add event listener for play event (see below).


Pauses playback.


The playback is paused immediately.


Changes the playback location to time t given in seconds (e.g. 15) or percentage (e.g '50%').

This function returns a promise which is fulfilled when the location actually changes. => {
  console.log(`current time: ${player.getCurrentTime()}`);

addEventListener(eventName, handler)

Adds event listener, binding handler's this to the player object.

The play event is dispatched when playback starts or resumes from pause.

player.addEventListener('play', () => {
  console.log(`playing! we're at: ${this.getCurrentTime()}`);

The pause event is dispatched when playback is paused.

player.addEventListener('pause', () => {

The ended event is dispatched when playback stops after reaching the end of the recording.

player.addEventListener('ended', () => {


Use this function to dispose of the player, i.e. to shut it down, release all resources and remove it from DOM.

Keyboard shortcuts

The following keyboard shortcuts are currently available (when the player element is focused):

  • space - play / pause
  • f - toggle fullscreen mode
  • / - rewind by 5 seconds / fast-forward by 5 seconds
  • Shift + / Shift + - rewind by 10% / fast-forward by 10%
  • 0, 1, 2 ... 9 - jump to 0%, 10%, 20% ... 90%


The project requires Node.js, npm and Rust for development and build related tasks so make sure you have the latest versions installed.

To build the project:

git clone
cd asciinema-player
git submodule update --init
rustup target add wasm32-unknown-unknown
npm install
npm run build
npm run bundle

This produces:

  • dist/index.js - ES module, to be import-ed in your JS bundle
  • dist/bundle/asciinema-player.js - standalone player script, to be linked directly from a website
  • dist/bundle/asciinema-player.min.js - minimized version of the above
  • dist/bundle/asciinema-player.css - stylesheet, to be linked directly from a website or included in a CSS bundle


If you want to contribute to this project check out Contributing page.


Developed with passion by Marcin Kulik and great open source contributors.


Copyright © 2011-2022 Marcin Kulik.

All code is licensed under the Apache License, Version 2.0. See LICENSE file for details.