dev-browser

dev-browser is a skill for Claude Code from Vibe-Marketer/plugins-and-skills. It costs 84 tokens per session (2,095 once invoked), scanned A, original, MIT.

A browser-automation guide for navigating websites, filling forms, taking screenshots, collecting web data, and testing web apps while keeping page state between actions.

In plain words
What is it for?
Use it to automate website workflows, inspect page elements, scrape information, capture visual results, and test online applications.
Why use it?
It reduces repetitive browser work and helps the agent interact with pages it has not seen before.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the dev-toolkit plugin — 9 skills shipped together

Good fit Use it to automate website workflows, inspect page elements, scrape information, capture visual results, and test online applications.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vibe-marketer/plugins-and-skills/dev-browser
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Vibe-Marketer/plugins-and-skills --skill dev-browser
Clone the repo
git clone --depth 1 https://github.com/Vibe-Marketer/plugins-and-skills

Made for: Claude Code.

Or install dev-toolkit, the plugin that ships this one along with the rest of its 9 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for dev-browser

README.md
[![agentmods](https://agentmods.dev/badge/skills/vibe-marketer/plugins-and-skills/dev-browser/github.svg)](https://agentmods.dev/skills/vibe-marketer/plugins-and-skills/dev-browser)
Your own site
<a href="https://agentmods.dev/skills/vibe-marketer/plugins-and-skills/dev-browser"><img src="https://agentmods.dev/badge/skills/vibe-marketer/plugins-and-skills/dev-browser/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for dev-browser

Your own site · 80×15
<a href="https://agentmods.dev/skills/vibe-marketer/plugins-and-skills/dev-browser"><img src="https://agentmods.dev/badge/skills/vibe-marketer/plugins-and-skills/dev-browser.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 84 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,095 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00084 $0.02095
Opus 5.5 $0.00034 $0.00838
Sonnet 5.5 $0.00017 $0.00419
Haiku 4.5 $0.00008 $0.00210

Measured 1mo ago against content hash 1932db4e9fd0, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

dev-browser scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

The scan reads SKILL.md. This mod also ships 12 executable files (scripts/start-relay.ts, scripts/start-server.ts, server.sh, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

dev-toolkit/skills/dev-browser/SKILL.md · 263 lines

How it starts

The opening of the file, as written. The whole thing — 263 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Dev Browser Skill

Browser automation that maintains page state across script executions. Write small, focused scripts to accomplish tasks incrementally. Once you've proven out part of a workflow and there is repeated work to be done, you can write a script to do the repeated work in a single execution.

Choosing Your Approach

  • Local/source-available sites: Read the source code first to write selectors directly
  • Unknown page layouts: Use getAISnapshot() to discover elements and selectSnapshotRef() to interact with them
  • Visual feedback: Take screenshots to see what the user sees

Setup

IMPORTANT: Always use Standalone Mode for browser automation. Extension Mode is rarely needed.

Standalone Mode (Default)

Launches a Chromium browser with a persistent profile. Login sessions, cookies, and local storage persist across browser restarts.

Start the server:

~/.config/amp/skills/dev-browser/server.sh &

Wait for the Ready message before running scripts. Add --headless flag if user requests headless mode.

Key points:

  • Profile stored at ~/.config/amp/skills/dev-browser/profiles/browser-data
  • Once logged in, future sessions remain authenticated
  • Use this mode for local dev testing with auth (localhost:3000, etc.)

Extension Mode (Rarely Used)

Connects to user's existing Chrome browser. Only use when explicitly requested - the user must install a browser extension.

cd ~/.config/amp/skills/dev-browser && npm i && npm run start-extension &

Download link: https://github.com/SawyerHood/dev-browser/releases

Writing Scripts

Run all scripts from the dev-browser directory. The @/ import alias requires this directory's config.

Execute scripts inline using heredocs:

cd ~/.config/amp/skills/dev-browser && npx tsx <<'EOF'
import { connect, waitForPageLoad } from "@/client.js";

const client = await connect();
const page = await client.page("example"); // descriptive name like "cnn-homepage"
await page.setViewportSize({ width: 1280, height: 800 });

await page.goto("https://example.com");
await waitForPageLoad(page);

console.log({ title: await page.title(), url: page.url() });
await client.disconnect();
EOF

Read the full file on GitHub · 263 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 263 lines · 84 tokens per session scan A 1932db4e9fd0

Subscribe to this mod's changes

dev-browser is a skill published in the GitHub repository Vibe-Marketer/plugins-and-skills (2 stars, last pushed 7mo ago), licensed MIT. It adds 84 tokens to every session and 2,095 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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