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Derive API Client

Records a site's network traffic once, then writes a standalone client that calls its internal API directly.

Source Download skill
Repository
vercel-labs/agent-browser
Stars
45,202
Licence
Apache-2.0
Files
1 file

What it does

Normally an AI agent drives a web browser every time it needs something from a website, which is slow and fragile. This skill has the agent record the browser's network traffic once while it uses the site, then study the recorded requests and generate a small script or command-line tool that calls the site's internal API directly, without opening a browser. The generated client is meant to be re-run for repeated tasks, and the skill includes steps to test each endpoint against the live site before it is considered finished.

Great for

  • Developers who repeatedly automate the same website and want faster, lighter scripts than browser automation
  • Data users who need a repeatable way to pull structured results from a site that has no public API
  • Engineers prototyping an unofficial client for a site they are allowed to access

Skip it if

  • Sites with a public, documented API, where using it is safer and more stable than reverse engineering
  • Situations where the site's terms of service prohibit automated access or scraping, since the skill itself says to respect terms and rate limits but cannot check them
  • Sensitive accounts such as banking or email, because the recordings contain live session cookies and tokens that must be handled as secrets

Try asking

  • “Derive a client for this site: record a search and a product detail page, then build a CLI that fetches results”
  • “Reverse engineer this site's API from a recorded browser session and write a Python client”
  • “Turn this site into an API by recording the flows I use, then generate functions for each one”
Step-by-step guide: how to use Derive API ClientInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 1 original files, the Apache-2.0 licence and an attribution note.

    derive-client.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip derive-client.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip derive-client.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Run each recorded flow at least twice with different inputs so the agent can tell which parts of URLs are parameters.
  • Log in before starting the HAR recording and keep the HAR file out of version control, then delete it when finished.
  • Expect internal APIs to change without notice; keep the HAR so the client can be re-derived when it breaks.

What's inside

  • SKILL.md

Redistributed unmodified from vercel-labs/agent-browser under the Apache-2.0 licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.