screenshot-local

Screenshot Local — shot-scraper

Overview

Capture screenshots of local dev servers and static HTML files with shot-scraper, a Playwright wrapper installed via pipx. Prefer a committed shots.yml over one-off commands whenever more than one image is involved — a capture the repo can regenerate stays current, while a manual one rots the moment the UI changes.

Install

pipx install shot-scraper     # brew install pipx / apt install pipx first
shot-scraper install          # downloads Chromium
shot-scraper --version

command not found after installing means pipx isn't on PATH: run pipx ensurepath, then reopen the shell.

Command Surface

Subcommand	Purpose
shot-scraper URL	One screenshot
shot-scraper multi shots.yml	Batch from YAML
shot-scraper pdf URL	PDF export
shot-scraper auth URL auth.json	Save a login session for reuse
shot-scraper accessibility URL	Dump the accessibility tree as JSON

Flag	Purpose
-o	Output filename (- for stdout)
-w / -h	Viewport width / height — omit -h for a full-page shot
-s / --selector-all	Capture the first / every matching element
-p	Padding around the selector, in px
--retina	2x device pixel ratio
--quality N	Save as JPEG at quality N
--wait N / --wait-for "expr"	Wait N ms / until a JS expression is truthy
-j "js"	Run JS before capture — dismiss modals, seed state
-a auth.json	Reuse a saved auth context
-i / --devtools	Open the browser to debug a shot interactively

Every flag and YAML key: reference/COMMAND-REFERENCE.md. Upstream docs: https://shot-scraper.datasette.io/.

Dimensions to use when the user doesn't name any:

Use case	Width	Height
README hero	1280	800
Docs screenshot	1200	omit (full page)
Social / OG image	1200	630
Mobile / tablet	375 / 768	812 / 1024

Sample Invocation

One-off captures:

shot-scraper http://localhost:3000 -o homepage.png
shot-scraper index.html -o preview.png
shot-scraper http://localhost:3000 -w 1200 -h 630 -o og.png
shot-scraper http://localhost:3000 -s ".hero" -p 20 --retina -o [email protected]
shot-scraper http://localhost:3000 --wait-for "document.querySelector('.loaded')" -o app.png

Setting up a project's screenshots: read its router config, page files, or nav to find the real routes and the dev-server port, choose the states worth documenting (populated beats empty), write shots.yml, then run shot-scraper multi shots.yml. Expect the first run to need timing or selector adjustments — open the resulting images and confirm they show the intended UI before reporting the job done.

✅ Explicit dimensions, an SPA wait, output under a directory, transient chrome removed:

- url: http://localhost:3000
  output: screenshots/homepage.png
  width: 1280
  height: 800

- url: http://localhost:3000/dashboard
  output: screenshots/dashboard.png
  width: 1280
  height: 900
  wait: 2000
  javascript: |
    document.querySelector('.toast-notification')?.remove()

❌ Captures the loading spinner into a machine-dependent auto-named file dumped at the repo root:

- url: http://localhost:3000/dashboard

✅ Fixed-dimension OG image — both -w and -h set, --retina omitted:

shot-scraper http://localhost:3000 -w 1200 -h 630 -o og.png

❌ --retina on a spec'd size — writes a 2400×1260 file into a slot that wants 1200×630, and the failure stays invisible until the card renders wrong:

shot-scraper http://localhost:3000 -w 1200 -h 630 --retina -o og.png

✅ Full-page docs capture — omit -h deliberately so height tracks content:

shot-scraper http://localhost:3000/docs -w 1200 -o docs.png

❌ Fixed -h on a docs page — clips everything below 800px, and the missing sections look like they were never written:

shot-scraper http://localhost:3000/docs -w 1200 -h 800 -o docs.png

Starter configs per project type — SPA, Storybook, responsive sweep, static site, auth: reference/TEMPLATES.md.

Failure Modes

• "Connection refused" — nothing is serving that port. Start the dev server (npm run dev &), confirm with curl -I http://localhost:3000, or hand the lifecycle to shot-scraper via the YAML server: key.
• Blank page or a loading spinner — the SPA hadn't hydrated when the shot fired. Prefer --wait-for "document.querySelector('.content')" over a fixed --wait 3000, because a fixed wait tuned on a warm laptop fails on a slower CI runner.
• Empty image or the wrong element — the selector matched nothing, or the content lazy-loads below the fold. Reproduce with -i and inspect the live page instead of guessing at another selector.
• Timeout on a heavy page — raise --timeout 30000. The default gives up sooner than a cold Next.js dev server takes to compile a route on first request.
• Passes locally, fails in CI — the runner never ran shot-scraper install, so no browser engine exists. Install the engine as its own CI step.

Gotchas

• shot-scraper install is a second, separate step. pipx install shot-scraper alone leaves no browser engine behind, so the first capture on a fresh machine fails.
• --quality switches the format to JPEG regardless of the output extension. --quality 80 -o hero.png writes JPEG bytes into a file named .png (verified on 1.9.1). Omit --quality when you want a real PNG.
• --retina doubles the output pixels, not the layout. -w 1200 --retina produces a 2400px-wide file, which breaks fixed-size targets like a 1200×630 OG image. Use it for README art, not for spec'd dimensions.
• A per-shot auth: key in shots.yml is silently ignored — the shot still succeeds, just logged out, so the failure looks like a broken page rather than missing auth. Pass auth to the whole batch instead: shot-scraper multi shots.yml -a auth.json.
• Omitting -h makes the height track the content, so two captures of the same route can differ in size. Set an explicit -h for before/after pairs.
• The YAML server: process spans the entire multi run and is torn down at the end (--leave-server keeps it). One server: entry covers the batch; repeating it per shot doesn't start more servers.
• A full-page capture hides small defects. Judging a 12px label, a contrast problem, or a clipped cell from a 1200px-wide image is guesswork. Capture the region with -s <selector> (plus -p padding) or crop the PNG before reading it — the model does its best visual work on a region it can look at up close.
• Screenshots don't diff cleanly. Antialiasing and font rendering make PNG diffs noisy, so keep shot-scraper for documentation artifacts and reach for Percy, Chromatic, or Playwright's toHaveScreenshot when the goal is a regression gate.

CI

Regenerate screenshots on source changes with a GitHub Actions workflow and commit them back — full workflow, cost controls, and the server: key pattern: reference/CI-INTEGRATION.md.