asciinema

Records a terminal session into a small text file that replays as real, selectable text.

What it does

asciinema records stdin/stdout timing into a .cast file — JSON, not video. Playback is a real terminal replay: text can be selected and copied, the file is a few kilobytes instead of megabytes, and it diffs.

asciinema rec demo.cast
asciinema play demo.cast
asciinema play -s 2 -i 0.5 demo.cast   # 2x speed, cap idle at 0.5s
asciinema upload demo.cast

Embedding

Casts can be self-hosted with the asciinema-player JavaScript component, or uploaded to asciinema.org. For documentation, a cast beats a GIF: smaller, copyable, and readable at any zoom level.

Alternative to

Alternative	Type	Trade-off
VHS	Open source	Charm’s tool: scripted, deterministic recordings that produce GIFs
t-rec and terminalizer	Open source	Record to GIF directly, larger files
Gifski plus a screen recording	Open source	The brute-force route, and it looks fine
`script(1)`	Built in	Captures the text without timing, already installed