Docker Compose Ports Checker

Check Docker Compose ports, find duplicate host ports, invalid port mappings, protocol issues, ranges, exposed ports, and service port conflicts directly in your browser.

Docker Compose YAML

Paste a Docker Compose file to check published ports, exposed ports, duplicate host ports, and service-level port mapping problems.

Check Options

Output

Check host conflictsFind services trying to publish the same host port.Check container portsWarn when several services use the same container port.Warn privileged portsWarn when host ports are below 1024.Warn unquoted portsSuggest quoting port mappings like "8080:80".

Ports Output

Docker Compose ports output will appear here.

Docker Compose port checking happens directly in your browser. Your YAML is not uploaded to a server.

Checking Docker Compose Port Conflicts Before Running Containers

Docker Compose port issues are common when several services try to publish the same host port. A web app, admin panel, database UI, or local debug service can fail to start because another container is already using the port.

This Docker Compose Ports Checker reads the ports and expose sections from a Compose file and shows published ports, container ports, duplicate host ports, invalid mappings, privileged ports, and useful notes before you run the stack.

Reviewing Ports in a Compose File

Paste your Docker Compose YAML into the input box.
Choose whether to check host ports, container ports, and low ports.
Run the checker to see published and exposed ports.
Review conflicts, invalid mappings, and quoting suggestions.
Copy the summary, JSON, or table output for notes or fixes.

Common Docker Compose Ports Checker Use Cases

Finding two services using the same host port.
Checking localhost-bound ports like 127.0.0.1:9229:9229.
Reviewing published ports before sharing a Compose file.
Finding unquoted port mappings that may be confusing in YAML.
Checking exposed-only ports that are not published to the host.
Preparing cleaner debugging notes for a Compose startup issue.

Example Port Mapping

services:
  web:
    ports:
      - "8080:80"
      - "127.0.0.1:9229:9229"

  admin:
    ports:
      - "8080:8080"

Ports and Expose Are Not the Same

The ports section publishes a container port to the host machine. The expose section only documents or exposes ports inside the Docker network. A service can be reachable by other containers without being published to your laptop or server.

When a container is not reachable from the browser or API client, check whether the port is actually published under ports and whether another service is already using the same host port.

Frequently Asked Questions

What does a Docker Compose ports checker do?

It reads Docker Compose YAML and checks published ports, exposed ports, duplicate host ports, invalid mappings, and common port configuration issues.

Can this find duplicate host ports?

Yes. It can show when two services publish the same host port, which often causes one container to fail at startup.

Does this run Docker Compose?

No. This tool only checks the YAML text. It does not run Docker or connect to your machine.

Is my Compose file uploaded anywhere?

No. Port checking happens directly in your browser, and your YAML is not uploaded to a server.