webreel

webreel records scripted browser demos as MP4, GIF, or WebM with cursor animation, keystroke overlays, and sound effects. You define steps in a JSON config, and webreel drives headless Chrome, captures frames, and encodes with ffmpeg.

Installation

Install webreel as a project dependency so the version is pinned in the lockfile. This ensures deterministic recordings across machines and CI.

npm install webreel

If the project already has webreel in its dependencies, skip this step.

Prerequisites

webreel requires Chrome and ffmpeg, but you do NOT need to install them manually. Both are automatically downloaded to ~/.webreel on first run if not already present. Do not install Chrome or Chromium via puppeteer, playwright, or any other tool. webreel manages its own browser.

To download dependencies explicitly, or to fix corrupted/broken binaries:

npx webreel install
npx webreel install --force   # delete cached binaries and re-download

To override the auto-downloaded binaries, set these environment variables:

• CHROME_PATH - path to a Chrome or Chromium binary (used for preview)
• CHROME_HEADLESS_PATH - path to a chrome-headless-shell binary (used for recording)
• FFMPEG_PATH - path to an ffmpeg binary

If a recording fails with "No inspectable targets" or similar browser errors, the issue is almost certainly in the webreel config (wrong waitFor, missing element, timing), not a missing browser. Check the config and use --verbose to debug.

.gitignore

The .webreel directory is created at the project root during recording (frames, intermediate files). Add it to .gitignore:

.webreel

Quick start

# Scaffold a config
npx webreel init --name my-demo --url https://example.com

# Edit webreel.config.json with your steps

# Preview in a visible browser (no recording)
npx webreel preview my-demo

# Record the video
npx webreel record my-demo

npx resolves to the locally installed version when webreel is in devDependencies. Output lands in videos/ by default (configurable via outDir).

CLI commands

init

Scaffold a new webreel.config.json.

webreel init
webreel init --name login-flow --url https://myapp.com
webreel init --name hero -o hero.config.json

Flags: --name (video name), --url (starting URL), -o, --output (output file path).

record

Record one or more videos.

webreel record                        # all videos in config
webreel record hero login             # specific videos by name
webreel record -c custom.config.json  # custom config path
webreel record --watch                # re-record on config change
webreel record --verbose              # log each step
webreel record --dry-run              # print resolved config only
webreel record --frames               # save raw JPEGs to .webreel/frames/

preview

Run steps in a visible browser without recording.

webreel preview
webreel preview hero --verbose

composite

Re-apply overlays (cursor, HUD, sfx) to existing raw video without re-recording. Useful for tweaking theme settings.

webreel composite
webreel composite hero

install

Download Chrome and ffmpeg to ~/.webreel. Also use this to fix corrupted or broken binaries.

webreel install
webreel install --force  # delete cached binaries and re-download

validate

Check config for errors without running anything.

webreel validate
webreel validate -c custom.config.json

Config structure

Config files are auto-discovered as webreel.config.json (or .ts, .mts, .js, .mjs). Use -c to specify a custom path.

Top-level fields

Per-video fields

Each entry in the videos map supports:

Videos map

Videos are keyed by name in the config:

{
  "videos": {
    "hero": { "url": "...", "steps": [...] },
    "login": { "url": "...", "steps": [...] }
  }
}

Record specific videos by name: webreel record hero login.

Step types

Each step has an action field. Most steps accept optional label, delay (ms after step), and description fields.

For full field details on every step type, see steps-reference.md.

Element targeting

Many steps target elements using these fields:

• text - match by visible text content
• selector - match by CSS selector
• within - narrow the search to a parent matching this CSS selector

You can use text or selector (not both). within is optional and scopes the search.

{ "action": "click", "text": "Submit" }
{ "action": "click", "selector": "#submit-btn" }
{ "action": "click", "text": "Submit", "within": ".modal" }

Viewport presets

Use preset names as string values for viewport, or specify { width, height }:

desktop (1920x1080), desktop-hd (2560x1440), laptop (1366x768), macbook-air (1440x900), macbook-pro (1512x982), ipad (1024x1366), ipad-pro (834x1194), ipad-mini (768x1024), iphone-15 (393x852), iphone-15-pro-max (430x932), iphone-se (375x667), pixel-8 (412x915), galaxy-s24 (360x780).

Theme

Customize cursor appearance and keystroke HUD:

{
  "theme": {
    "cursor": {
      "image": "./cursor.svg",
      "size": 32,
      "hotspot": "center"
    },
    "hud": {
      "background": "rgba(30, 41, 59, 0.85)",
      "color": "#e2e8f0",
      "fontSize": 48,
      "fontFamily": "\"SF Mono\", monospace",
      "borderRadius": 12,
      "position": "top"
    }
  }
}

• cursor.image - path to a custom cursor SVG or PNG
• cursor.size - cursor size in pixels
• cursor.hotspot - "top-left" (default) or "center"
• hud.position - "top" or "bottom"

Common patterns

Shared steps via include

Factor out reusable step sequences (e.g. dismissing a cookie banner) into JSON files:

// steps/dismiss-banner.json
{
  "steps": [
    { "action": "wait", "selector": ".cookie-banner", "timeout": 5000 },
    { "action": "click", "selector": ".accept-btn", "delay": 300 }
  ]
}

Reference them in the config:

{
  "include": ["./steps/dismiss-banner.json"],
  "videos": { ... }
}

Multiple videos in one config

Define several videos in the videos map. Shared settings (viewport, theme, defaultDelay) are inherited from the top level.

Environment variables

Config values support $VAR and ${VAR} substitution from the environment.

Output formats

Set the output extension to control format: .mp4 (default), .gif, .webm.

{ "output": "demo.gif" }

Tips

• Always set waitFor on a video to ensure the page is ready before steps run.
• Use delay on individual steps to control pacing between actions.
• Use --watch during development for automatic re-recording on config changes.
• Use composite to iterate on theme/overlay settings without re-recording.
• Use --verbose to debug step execution.
• Use --dry-run to inspect the fully resolved config (includes, env vars, defaults).
• Use zoom to scale up small UIs for readability in the recording.
• Start with preview to verify steps work before committing to a full recording.

Reference files

• steps-reference.md - detailed docs for all 12 step types
• examples.md - annotated config examples for common use cases