Traffic

Read captured request and response traffic from the terminal or an AI agent.

LocalCan's inspector records the HTTP traffic flowing through your proxy and Public URLs (tunnels). The localcan traffic commands expose that data on the command line, and localcan mcp exposes it to AI agents over the Model Context Protocol. Both read the exact same captured exchanges as the desktop inspector.

Capture is off by default and lives in memory only. The inspector keeps the most recent 250 exchanges and clears them when the daemon restarts. Turn it on with localcan traffic enable.

An exchange is recorded once its response completes, so a slow or still-running request does not appear in ls or watch until it finishes. WebSocket connections are the exception and appear when the connection opens.

Commands

localcan traffic status

Show whether capture is on, how many exchanges are buffered, and how much memory and disk they use.

localcan traffic enable and localcan traffic disable

Turn traffic capture on or off.

localcan traffic clear

Drop all captured traffic.

localcan traffic ls [filters]

List recent exchanges, newest first, then exit. Columns: ID, TIME, METHOD, STATUS, DUR, PATH, HOST. Narrow the results with the filters below. With --json each row is one NDJSON object:

JSON
{"id":"9f3a1c2d4e5f60718293a4b5c6d7e8f0","method":"POST","status":201,"path":"/v1/orders","host":"my-app-12.localcan.dev","project_id":"my-app","duration_ms":37,"req_bytes":18,"resp_bytes":120,"replayed":false,"time":"2026-06-29T10:14:22Z"}
localcan traffic get <id> [--format <fmt>] [--redact]

Export one exchange. The <id> can be the full id or any unique prefix, such as the short id shown by traffic ls. The --format is one of markdown (default), curl, http, har, or json. Output is written verbatim, so you can redirect or pipe it:

Shell
localcan traffic get 9f3a1c2d --format har > exchange.har
localcan traffic get 9f3a1c2d --format curl | sh

Exports include real header and cookie values by default. You ran the command and the data goes to your own terminal. Pass --redact to strip sensitive headers (Authorization, cookies, API keys). URLs and bodies are not redacted. The global --json flag is shorthand for --format json.

localcan traffic watch [filters]

Stream new exchanges live as they complete, until you press Ctrl-C. Takes the same filters as ls, except --last (there is no backlog, ls covers history). With --json each line is an NDJSON event carrying "event":"exchange":

Shell
localcan traffic watch --status 5xx --json | jq .

Filters

ls and watch take the same filters, and a row must match every one you pass. The exception is --last, which applies only to the ls snapshot.

  • --last N: cap the number of rows (ls only, default 20). Rows are newest first.
  • --host SUBSTRING: case-insensitive substring of the public host the client connected to (the *.localcan.dev, .local, or custom domain), captured before any Host rewrite for your backend. For example, --host my-app matches my-app-12.localcan.dev.
  • --project ID: exact project id, such as my-app (not the display name).
  • --method METHOD: exact HTTP method, case-insensitive, such as --method post.
  • --status STATUS: match the response status. Accepts an exact code (200, 404, 500) or a class (1xx, 2xx, 3xx, 4xx, 5xx) covering any code in that range. Exchanges still in flight match no status filter.

Examples:

Shell
# Newest 50 failed requests to one Public URL
localcan traffic ls --status 5xx --host my-app-12.localcan.dev --last 50

# Live POSTs that returned any 4xx, as NDJSON piped to jq
localcan traffic watch --method POST --status 4xx --json | jq .

# Everything for one project
localcan traffic ls --project my-app

Read it from an AI agent

AI agents can read this same captured traffic. An agent that runs shell commands can use traffic ls --json and traffic get, and agents that speak the Model Context Protocol get first-class tools through localcan mcp. See AI agents for both paths and per-host setup.

What an export represents

A captured request is the request LocalCan forwarded to your backend, not a byte-for-byte copy of the original client request. The exported url is the backend target, and the headers include LocalCan's x-forwarded-* plus any rewritten Host or injected values. The reconstructed client-facing address is reported separately as public_url. A cURL export therefore reproduces the request against your backend, which is what you usually want when debugging a handler.

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