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New in 1.1

Change the proxy port

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ReqRes's proxy listens on 127.0.0.1:8034 by default, and your Mac's system proxy points there while capture runs. Change the port if another tool needs 8034.

Change the port

  1. Open Settings ▸ Capture.
  2. Under Proxy port, type the new port in the Port field.
  3. Click Apply, or press Return.
  4. Start capture. If it is already running, restart it.

The port must be from 1024 to 65535. Ports below 1024 are reserved for the system, and ReqRes keeps 50001 for itself, between the app and its extension. If ReqRes refuses the value, a line under the field says why, for example "Enter a number from 1024 to 65535." The line stays only while the field holds the value it refused, so it goes as soon as you change the value.

To go back to the default, click Use 8034. The button appears while the port is set to anything else.

When a new port applies

A new port applies the next time capture starts. Capture that is already running keeps its port.

While capture runs on the old port, the section says so, for example "Capture is running on port 8034; port 8035 applies when capture starts again." Click Restart Capture to switch now.

Copy the environment lines again

Terminal tools reach ReqRes through the environment lines in Settings ▸ Capture, and those lines name the port. The block always shows the port you set. A terminal set up before the change still sends its requests to the old port, so they do not reach ReqRes.

  1. In Settings ▸ Capture, click Copy above the Environment block.
  2. Paste the lines into each terminal you capture from. If they are in your shell profile, update them there.
  3. Restart the tool from that terminal.

An AI agent gets the lines from the capture_environment MCP tool. While capture runs, the tool prints the port capture runs on, so it names the new port once capture restarts. See Capture command-line tools and agents.

When another program holds the port

If another program listens on the port when you start capture, capture does not start. ReqRes names the program and asks what to do:

Port 8034 is in use

Python is listening on 127.0.0.1:8034, where ReqRes's proxy runs, so capture did not start. Use port 8035 instead? Command-line tools set up with the environment lines will need the new lines.
  • Use Port 8035 saves the offered port and starts capture on it. ReqRes offers the next free port after the busy one.
  • Cancel keeps the port. Quit the other program, then start capture again.

ReqRes never moves to another port by itself. Shell profiles and scripts point at the number, so a silent move would break them.

If ReqRes cannot tell which program holds the port, the alert says "Another program is listening" instead of a name. If it finds no free port to offer, it asks you to quit the program or choose another port in Settings ▸ Capture.

Check which port is in use

  • Capture ▸ Diagnose Setup… checks the proxy port while capture runs. If capture is on but nothing listens on the port, it reports "Proxy port: Capture says it is on, but nothing is listening on 127.0.0.1:8034 — the proxy could not bind its port." Stop capture, quit anything else that uses the port, and start capture again. See Run Diagnose Setup.
  • Help ▸ ReqRes Help ▸ Setting Up Capture names the port set in Settings ▸ Capture.
  • An AI agent's capture_status tool reports the port capture runs on, as in Proxy: 127.0.0.1:8035.

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