Reverse API Engineer

Turn websites into APIs. Browse (or let an agent browse), and get a clean, typed client for the endpoints the site actually uses.

Agent mode

Manual mode

---

How it works

1. You give it a website and a goal ("fetch all Apple jobs").
2. A browser visits the site, either driven by you or by an AI agent.
3. Network traffic is captured to a HAR file.
4. Your configured model reads the traffic and writes a working API client in Python, JavaScript, TypeScript, Go, Java, C#, PHP, Ruby, or C.

No more manually opening DevTools, copying cURL commands, and gluing together a client.

Install

uv tool install reverse-api-engineer   # or: pip install reverse-api-engineer

Agent mode (the default) captures through npx-launched browser tooling — browser MCP servers (Playwright or Chrome DevTools) or the Vercel agent-browser CLI — and needs no extra Python packages. Manual mode drives a local Playwright browser, which ships in the optional [manual] extra:

uv tool install "reverse-api-engineer[manual]"   # or: pip install "reverse-api-engineer[manual]"
playwright install chromium

Quick start

reverse-api-engineer
> fetch all apple jobs from their careers page

# Browser opens. Navigate, interact, close when done.
# → ./scripts/apple_jobs_api/  (api_client.py, README.md, example_usage.py)

Cycle modes with Shift+Tab:

Mode	What it does
manual	You drive the browser; AI generates the client from captured traffic.
agent	An AI agent drives capture autonomously (Playwright or Chrome MCP, or Vercel agent-browser CLI).
engineer	Re-run generation on a previous capture (engineer <run_id>).
collector	Agent collects structured data (JSON/CSV) using web search + fetch.

Agent mode providers:

• auto (default): Playwright MCP, single workflow for browsing + reverse engineering.
• chrome-mcp: drives your real Chrome so you keep existing sessions/cookies. Requires Chrome 146+ and Node.js 20.19+.
• agent-browser: Vercel agent-browser CLI (not a Reverse API Engineer browser MCP server). At session start RAE uses whatever agent-browser is already on PATH, otherwise runs npm install -g <pin> (same pin as config / RAE_AGENT_BROWSER_PACKAGE), prints a yellow notice, validates with --help, and only then falls back to npx -y <pin> if npm cannot install. Prompts embed the resolved shell prefix alongside skills get core --full, skills list, HAR phases, cloud notes from agent_browser_notes. Tune with agent_browser_npx_package (optional), env RAE_AGENT_BROWSER_*. First Chromium fetch: agent-browser install (add --with-deps on trimmed Linux).

Optional sanity checks:

agent-browser doctor --offline --quick || true
agent-browser skills list >/dev/null

Configuration

Settings live in ~/.reverse-api/config.json and can be edited via /settings in the CLI:

{
  "agent_provider": "auto",
  "agent_browser_npx_package": "agent-browser@0",
  "agent_browser_notes": "",
  "claude_code_model": "claude-sonnet-4-6",
  "collector_model": "claude-sonnet-4-6",
  "ollama_auto_start": true,
  "ollama_base_url": "http://127.0.0.1:11434",
  "opencode_auto_start": true,
  "opencode_base_url": "http://127.0.0.1:4096",
  "opencode_model": "big-pickle",
  "opencode_npx_package": "opencode-ai@latest",
  "opencode_provider": "opencode",
  "copilot_model": "gpt-5",
  "cursor_model": "composer-2.5",
  "output_dir": null,
  "output_language": "python",
  "real_time_sync": true,
  "sdk": "claude"
}

• Models: Sonnet 4.6 (default), Opus 4.6 (most capable), Haiku 4.5 (fastest). For OpenCode see models.dev.
• SDK: claude (default), opencode, cursor, or copilot (GitHub Copilot).
• OpenCode setup: with sdk: "opencode", RAE reuses an existing server or downloads/starts opencode-ai@latest through npx; a global OpenCode installation is not required. Fresh configurations default to the free opencode/big-pickle model. /settings shows a loading spinner, then offers a searchable OpenCode Provider / Model picker populated from the server's connected, tool-capable catalog and marks free OpenCode options. Before creating a session, RAE validates the saved pair again and suggests currently available free models when configuration is invalid. Compatible older servers are reused with a version warning. Node.js 20+ is required for automatic startup. Password-protected servers use OPENCODE_SERVER_PASSWORD and optional OPENCODE_SERVER_USERNAME. Override startup with OPENCODE_BASE_URL, RAE_OPENCODE_PACKAGE, or RAE_OPENCODE_AUTO_START=0.
• Ollama through OpenCode: choose provider ollama in /settings; RAE starts an installed Ollama daemon if needed, lists only installed models with tool calling and 64k+ context, and supplies OpenCode's provider config inline. Models are never downloaded silently. Override with RAE_OLLAMA_BASE_URL or RAE_OLLAMA_AUTO_START=0.
• Output language: python, javascript, typescript, go, java, csharp, php, ruby, or c. C needs a POSIX toolchain (cc, libcurl headers) — macOS/Linux, or WSL/MSYS2 on Windows.

CLI

Slash commands inside the CLI:

• /settings: configure model, SDK, agent provider, and sync settings.
• /history: list past runs with timestamps, costs, and status.
• /messages <run_id>: view detailed message logs for a run.
• /help (alias: /commands): show the command list.
• /exit (alias: /quit): leave the CLI.

Scriptable subcommands (pipe to jq):

reverse-api-engineer agent --prompt "capture the public jobs api" \
  --url https://example.com/jobs --json | jq

reverse-api-engineer list --json
reverse-api-engineer show <run_id> --json
reverse-api-engineer run <run_id> --file api_client.py \
  --no-interactive --auto-install -- --org acme

Pass --no-interactive (and/or --json) to skip prompts. With --json, stdout is one JSON document and logs go to stderr.

agent --json schema

Field	Type	Notes
schema_version	int	Currently 1.
status	"ok" | "error"	Top-level result.
run_id	string | null	Use with show / engineer / run.
prompt	string
url	string | null
mode	string | null	"auto", "chrome-mcp", or "agent-browser".
har_path	string | null	Captured HAR.
script_path	string | null	Generated client.
usage	object	{input_tokens, output_tokens, total_cost}.
error	string | null	When status == "error".

Exit codes

Code	Meaning
0	Success.
1	Runtime error.
2	Missing required arg under --no-interactive / --json.

For run, the exit code is the underlying script's return code on success, 1 if no script was found, or non-zero if --no-interactive would have had to prompt.

Output locations

• ~/.reverse-api/runs/scripts/{run_id}/: permanent storage
• ./scripts/{descriptive_name}/: local copy with a readable name
• Collector: ./collected/{folder_name}/ (items.json, items.csv, README.md)

Caveats

• Generated code runs locally via Claude Code, so review before executing.
• Sites with aggressive bot detection may block capture or require manual interaction.

Development

git clone https://github.com/kalil0321/reverse-api-engineer.git
cd reverse-api-engineer
uv sync
uv run reverse-api-engineer

Build: ./scripts/clean_build.sh. Requires Python 3.11+ and an API key for agent mode. Manual mode additionally needs the [manual] extra plus playwright install chromium.

License

MIT. See LICENSE.