claude-tap 0.1.43

Trace Claude Code API requests via a local reverse proxy. Inspect system prompts, messages, tools, and token usage.

claude-tap

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Intercept and inspect API traffic from Claude Code or Codex CLI. See exactly how they construct system prompts, manage conversation history, select tools, and use tokens — in a beautiful trace viewer.

Dark Mode / Diff View

Install

Requires Python 3.11+ and Claude Code (or Codex CLI for --tap-client codex).

# Recommended
uv tool install claude-tap

# Or with pip
pip install claude-tap

Upgrade: uv tool upgrade claude-tap or pip install --upgrade claude-tap

Usage

Claude Code

# Basic — launch Claude Code with tracing
claude-tap

# Live mode — watch API calls in real-time in browser
claude-tap --tap-live

# Pass any flags through to Claude Code
claude-tap -- --model claude-opus-4-6
claude-tap -c    # continue last conversation

# Skip all permission prompts (auto-accept tool calls)
claude-tap -- --dangerously-skip-permissions

# Full-power combo: live viewer + skip permissions + specific model
claude-tap --tap-live -- --dangerously-skip-permissions --model claude-sonnet-4-6

Codex CLI

Codex CLI supports two authentication modes with different upstream targets:

Auth Mode	How to authenticate	Upstream target	Notes
OAuth (ChatGPT subscription)	codex login	https://chatgpt.com/backend-api/codex	Default for ChatGPT Plus/Pro/Team users
API Key	Set OPENAI_API_KEY	https://api.openai.com (default)	Pay-per-use via OpenAI Platform

claude-tap auto-detects the Codex target from your auth state when possible.

# OAuth users (ChatGPT Plus/Pro/Team) — auto-detected after `codex login`
claude-tap --tap-client codex

# If auto-detection cannot read your Codex auth file, specify the target explicitly
claude-tap --tap-client codex --tap-target https://chatgpt.com/backend-api/codex

# API Key users — default OpenAI API target works out of the box
claude-tap --tap-client codex

# With specific model
claude-tap --tap-client codex -- --model codex-mini-latest

# Full auto-approval (skip all permission prompts)
claude-tap --tap-client codex -- --full-auto

# OAuth + full auto + live viewer
claude-tap --tap-client codex --tap-live -- --full-auto

Browser Preview

# Disable auto-open of HTML viewer after exit (on by default)
claude-tap --tap-no-open

# Live mode — real-time viewer opens in browser while client runs
claude-tap --tap-live
claude-tap --tap-live --tap-live-port 3000    # fixed port for live viewer

When the client exits, you can also manually open the generated viewer:

open .traces/*/trace_*.html

You can also regenerate a self-contained HTML viewer from an existing JSONL trace:

claude-tap export .traces/2026-02-28/trace_141557.jsonl -o trace.html
# or:
claude-tap export .traces/2026-02-28/trace_141557.jsonl --format html

Proxy-Only Mode

Start the proxy without launching a client — useful for custom setups or connecting from a separate terminal:

# Claude Code
claude-tap --tap-no-launch --tap-port 8080
# In another terminal:
ANTHROPIC_BASE_URL=http://127.0.0.1:8080 claude

# Codex CLI (OAuth)
claude-tap --tap-client codex --tap-target https://chatgpt.com/backend-api/codex --tap-no-launch --tap-port 8080
# In another terminal:
OPENAI_BASE_URL=http://127.0.0.1:8080/v1 codex -c 'openai_base_url="http://127.0.0.1:8080/v1"'

# Codex CLI (API Key)
claude-tap --tap-client codex --tap-no-launch --tap-port 8080
# In another terminal:
OPENAI_BASE_URL=http://127.0.0.1:8080/v1 codex -c 'openai_base_url="http://127.0.0.1:8080/v1"'

Run claude-tap --help for all options. Flags that are not --tap-* are forwarded to the selected client.

Viewer Features

The viewer is a single self-contained HTML file (zero external dependencies):

• Structural diff — compare consecutive requests to see exactly what changed: new/removed messages, system prompt diffs, character-level inline highlighting
• Path filtering — filter by API endpoint (e.g., /v1/messages only)
• Model grouping — sidebar groups requests by model, with Claude-family priority ordering
• Token usage breakdown — input / output / cache read / cache creation
• Tool inspector — expandable cards with tool name, description, and parameter schema
• Search — full-text search across messages, tools, prompts, and responses
• Dark mode — toggle light/dark themes (respects system preference)
• Keyboard navigation — j/k or arrow keys
• Copy helpers — one-click copy of request JSON or cURL command
• i18n — English, 简体中文, 日本語, 한국어, Français, العربية, Deutsch, Русский

Architecture

How it works:

1. claude-tap starts a reverse proxy and spawns the selected client (claude or codex) with the provider-specific base URL pointing to it
2. Supported API requests flow through the proxy → upstream API → back through proxy
3. SSE and WebSocket streams are forwarded as chunks/messages arrive with low proxy overhead
4. Each request-response pair or WebSocket session is recorded to a dated trace_*.jsonl
5. On exit, a self-contained HTML viewer is generated
6. Live mode (optional) broadcasts updates to browser via SSE

Key features: 🔒 Common auth headers auto-redacted · ⚡ Low-overhead streaming · 📦 Self-contained viewer · 🔄 Real-time live mode

Community

Contributing

Contributions are welcome. Start with CONTRIBUTING.md.

License

MIT