---
name: Before and After Screenshot
slug: before-and-after-screenshot
category: Automation
description: Before and After Screenshot captures before and after images of web pages or elements for visual comparison. Use it for UI changes, screenshot diffs, PR screenshots, or comparing two URLs or image files.
github: "https://github.com/michaelshimeles/skills/tree/main/before-and-after"
language: Python
stars: 538
forks: 92
install: "npx degit https://github.com/michaelshimeles/skills/tree/main/before-and-after ~/.claude/skills/before-and-after"
installs_to: ~/.claude/skills/before-and-after
source_path: before-and-after/SKILL.md
collection_size: 6
category_size: 1754
collection_url: "https://dirskills.com/collections/michaelshimeles/skills"
added: 2026-09-03T06:03:29.788Z
last_synced: 2026-09-03T06:03:29.788Z
canonical_url: "https://dirskills.com/skills/before-and-after-screenshot"
---

# Before and After Screenshot

Before and After Screenshot captures before and after images of web pages or elements for visual comparison. Use it for UI changes, screenshot diffs, PR screenshots, or comparing two URLs or image files.

**Install:**

```bash
npx degit https://github.com/michaelshimeles/skills/tree/main/before-and-after ~/.claude/skills/before-and-after
```

## README

# Before-After Screenshot Skill

> **Package:** `@vercel/before-and-after`
> Never use `before-and-after` (wrong package).

## Agent Behavior Rules

**DO NOT:**
- Switch git branches, stash changes, start dev servers, or assume what "before" is
- Use `--full` unless user explicitly asks for full page / full scroll capture

**DO:**
- Use `--markdown` when user wants PR integration or markdown output
- Use `--mobile` / `--tablet` if user mentions phone, mobile, tablet, responsive, etc.
- Assume current state is **After**
- If user provides only one URL or says "PR screenshots" without URLs, **ASK**: "What URL should I use for the 'before' state? (production URL, preview deployment, or another local port)"

## Execution Order (MUST follow)

1. **Pre-flight** — `which before-and-after || npm install -g @vercel/before-and-after`
2. **Protection check** — if `.vercel.app` URL: `curl -s -o /dev/null -w "%{http_code}" "<url>"` (401/403 = protected)
3. **Capture** — `before-and-after "<before-url>" "<after-url>"`
4. **Upload** — `./scripts/upload-and-copy.sh <before.png> <after.png> --markdown`
5. **PR integration** — optionally `gh pr edit` to append markdown

**Never skip steps 1-2.**

## Quick Reference

```bash
# Basic usage
before-and-after <before-url> <after-url>

# With selector
before-and-after url1 url2 ".hero-section"

# Different selectors for each
before-and-after url1 url2 ".old-card" ".new-card"

# Viewports
before-and-after url1 url2 --mobile    # 375x812
before-and-after url1 url2 --tablet    # 768x1024
before-and-after url1 url2 --full      # full scroll

# From existing images
before-and-after before.png after.png --markdown

# Via npx (use full package name!)
npx @vercel/before-and-after url1 url2
```

| Flag | Description |
|------|-------------|
| `-m, --mobile` | Mobile viewport (375x812) |
| `-t, --tablet` | Tablet viewport (768x1024) |
| `--size <WxH>` | Custom viewport |
| `-f, --full` | Full scrollable page |
| `-s, --selector` | CSS selector to capture |
| `-o, --output` | Output directory (default: ~/Downloads) |
| `--markdown` | Upload images & output markdown table |
| `--upload-url <url>` | Custom upload endpoint (default: 0x0.st) |

## Image Upload

```bash
# Default (0x0.st - no signup needed)
./scripts/upload-and-copy.sh before.png after.png --markdown

# GitHub Gist
IMAGE_ADAPTER=gist ./scripts/upload-and-copy.sh before.png after.png --markdown
```

## Vercel Deployment Protection

If `.vercel.app` URL returns 401/403:

1. Check Vercel CLI: `which vercel && vercel whoami`
2. If available: `vercel inspect <url>` to get bypass token
3. If not: Tell user to provide bypass token, take manual screenshots, or disable protection

## PR Integration

```bash
# Check for gh CLI
which gh

# Get current PR
gh pr view --json number,body

# Append screenshots to PR body
gh pr edit <number> --body "<existing-body>

## Before and After
<generated-markdown>"
```

If no `gh` CLI: output markdown and tell user to paste manually.

## Error Reference

| Error | Fix |
|-------|-----|
| `command not found` | `npm install -g @vercel/before-and-after` |
| `could not determine executable` | Use `npx @vercel/before-and-after` (full name) |
| 401/403 on .vercel.app | See Vercel protection section |
| Element not found | Verify selector exists on page |