Viset

Write browser screenshots and animations as code for testing and demoing your web apps.

Documentation  ·  Examples  ·  Benchmarks  ·  Contributing

Quick start

With Nix installed:

nix run github:getviset/Viset -- init demo
nix run github:getviset/Viset -- capture demo/capture.lua

Open demo/output/example.png. That is a complete, self-contained first capture; edit demo/capture.lua to point it at your page.

One file, every capture

The capture file keeps its configuration and browser actions together:

--[[
# viset
version = 1
output = "output/{device}-{theme}.png"

[devices.desktop.viewport]
width = 1280
height = 720

[matrix]
theme = ["light", "dark"]
]]

viset.page.navigate("https://example.com")
viset.snapshot()

Viset expands the matrix and writes both outputs. The same model supports multiple devices, framed captures, and continuous animated WebP recording.

Editor support

viset init generates the capture scaffold and LuaLS metadata. The optional editor integrations below only add highlighting for embedded TOML and JavaScript. They do not execute captures or replace initialization.

• Neovim 0.12+: install getviset/viset.nvim with your plugin manager and the Lua, TOML, and JavaScript Tree-sitter parsers.
• Emacs 30.1+: install getviset/viset.el from Git with package-vc-install. Emacs needs Tree-sitter support and compatible Lua, TOML, and JavaScript grammars.
• VS Code 1.130+: install the getviset.viset v0.1.0 VSIX from its GitHub release. getviset.viset is not currently listed on the Marketplace.

Built for reproducible capture

• Single-file intent. The strict TOML header and trusted Lua actions live in execution order.
• Matrix-native output. Declare devices and axes once; Viset expands them deterministically.
• Screenshots and motion. Capture PNG stills or pauseable animated WebPs.
• Direct ownership. Outputs are ordinary files ready for Git, docs, tests, or publishing.

Explore Viset

Read the wiki	Install Viset and learn the capture format and Lua API.
Try the examples	Start small, then explore device and theme matrices.
Review the benchmarks	See measured capture, encoder, pipeline, and decoder results.
Contribute	Build, test, format, and propose changes.

Status

Viset is pre-release software. The Nix flake is the supported public route today; release archives and package-manager channels will follow once they are verified.

Capture files are trusted local programs and are not sandboxed. Read a capture before running it.

Viset is available under the MIT License.