asciinema

asciinema is a terminal session recorder that captures everything printed to your terminal and saves it as a structured text file in the asciicast format (.cast), rather than a video. Because recordings are plain text, they are tiny, perfectly sharp at any resolution, and copyable — viewers can pause and copy-paste commands directly from a playback. The 3.x release rewrote the tool in Rust, replacing the previous Python implementation with a faster, dependency-free binary.

Features

• Lightweight recordings — asciicast files are highly compressible plain text, often shrinking to 15% of the original size with gzip or zstd.
• In-terminal replay — play recordings back directly in your terminal with asciinema play, no browser required.
• Live streaming — stream your terminal session in real time to multiple viewers via a built-in HTTP server or a relay such as asciinema.org.
• Web embedding — publish recordings to asciinema.org and embed the player in documentation, blog posts, or slides with a single <script> tag.
• Idle time trimming — automatically squash long pauses during recording with --idle-time-limit so replays stay snappy.
• Shell completion — ships completion scripts for bash, zsh, and fish.
• Self-hostable server — recordings can be published to any compatible asciinema server, not just asciinema.org.

Installation

cargo install --locked --git https://github.com/asciinema/asciinema

asciinema 3.x is not yet on crates.io, so installation from the Git repository is required for the current Rust version.

# Debian / Ubuntu — installs the older Python 2.x version from the archive
apt install asciinema

# Fedora
dnf install asciinema

# macOS
brew install asciinema

# Arch Linux
pacman -S asciinema

# Nix
nix-env -iA nixpkgs.asciinema

Note: Distribution packages currently ship the 2.x Python version. Install from source with cargo above to get the 3.x Rust version.

Usage

Recording a session

# Record to a file
asciinema rec demo.cast

# Record with a cap on idle time (pauses longer than 2 s are trimmed)
asciinema rec --idle-time-limit 2 demo.cast

# Append to an existing recording
asciinema rec --append demo.cast

Press ctrl-d or type exit to stop recording.

Replaying a recording

# Replay at recorded speed
asciinema play demo.cast

# Replay at double speed
asciinema play --speed 2 demo.cast

# Replay with idle time capped at 1 s
asciinema play --idle-time-limit 1 demo.cast

Inspecting a recording

# Print the full output of a session (no timing)
asciinema cat demo.cast

Publishing

# Upload to asciinema.org and get a shareable URL
asciinema upload demo.cast

# Record and upload in one step
asciinema rec --stdin demo.cast && asciinema upload demo.cast

Live streaming

# Stream via a local HTTP server (viewers open the printed URL)
asciinema stream --serve

# Stream via asciinema.org as a relay
asciinema stream --relay

asciicast format

Recordings are newline-delimited JSON files. Each line after the header is an event:

{"version": 2, "width": 220, "height": 50, "timestamp": 1700000000}
[0.248, "o", "$ "]
[1.002, "o", "ls -lh\r\n"]
[1.134, "o", "total 4.0K\r\n-rw-r--r-- 1 user user 123 Jan 1 12:00 demo.cast\r\n"]

Because the format is plain text, recordings can be diffed, grepped, edited in any text editor, and processed with standard Unix tools.

asciinema vs screen recording video