Why can't someone else open my localhost link?

`localhost` and `127.0.0.1` are defined to mean 'this machine'. The recipient's browser resolves them against their own computer, finds nothing on that port, and shows a connection-refused error. No network configuration changes this — the name is the problem.

Does sending my LAN IP work instead?

Only if you are on the same network segment, the host firewall allows the port, and the server is bound to 0.0.0.0 rather than 127.0.0.1. It fails for anyone remote, and it stops working the moment your DHCP lease changes.

Should I use a tunnel like ngrok or Cloudflare Tunnel?

For live debugging of a running app, yes — that is what they are for. For a report, no: the URL dies when your laptop sleeps, the free tiers rotate the hostname, and you are exposing a local process to the internet to deliver a static document.

What is the right way to share a locally generated report?

Publish the file. Upload the report directory or POST the HTML and you get a permanent URL that does not depend on your machine being awake, with per-report access control and a place for readers to comment.

What if the report needs a live server to work?

Almost none do. Reports that appear to need one are usually just failing on `file://` because of blocked XHR — publishing them over HTTPS fixes that without keeping any process running.

`http://localhost:8080` will never open for them

You started a local server so the report would render, copied the address out of the URL bar, and pasted it into the thread. They reply: This site can't be reached.

The name means "your own machine"

localhost resolves to 127.0.0.1 — the loopback address, defined to mean the computer doing the resolving. When your colleague opens the link, their browser dials their port 8080, finds nothing, and gives up. The same is true of 0.0.0.0, 127.0.0.1, and anything under *.localhost.

There is no firewall rule, VPN setting or port forward that fixes this, because nothing is broken. The link is an instruction to look in the wrong place.

The things people try next

Send the LAN IP (http://192.168.1.34:8080). Works, sometimes, for a colleague on the same office network — provided the server is bound to 0.0.0.0 and not just loopback, and provided the host firewall permits inbound connections on that port. It fails for anyone remote, breaks when your DHCP lease changes, and is a support conversation every time.

Open a tunnel — ngrok, Cloudflare Tunnel, ssh -R, VS Code port forwarding. These genuinely work, and they are the right tool for a live thing: debugging a webhook, demoing an app mid-development, letting a client click through a running prototype.

They are the wrong tool for a report, because:

The URL dies when your laptop sleeps, and you find out via a message saying the link is broken.
Free tiers hand out a new random hostname each session, so the link in yesterday's thread is already dead.
You are exposing a process on your machine to the public internet in order to deliver a static document.
There is nowhere for the reader's comment to live.

Fuller comparison in ngrok alternatives.

Why you started the server at all

Usually because double-clicking the file didn't work. That is worth naming, because it points at the actual fix:

Reports that load their results over XHR — Allure, Playwright, most coverage UIs — render blank from file:// because a local file has an opaque origin and same-origin rules block the fetches. python -m http.server gives them a real origin, so they work.

But so does any HTTPS origin. The server was never the requirement — http:// was. Publishing the report satisfies it permanently instead of for as long as your terminal stays open.

Publish it instead

Drag the report directory (or a zip of it) into the app, or POST the HTML from the script that generated it:

curl -sS -X POST https://commareports.com/api/v1/reports \
  -H "Authorization: Bearer $COMMA_API_TOKEN" \
  -H "Content-Type: application/json" \
  --data @<(jq -Rs '{title: "Coverage", html: .}' htmlcov/index.html)

What you get: a URL that resolves from anyone's machine, assets uploaded alongside the entry file with their relative references rewritten, interactivity preserved inside a sandboxed iframe, per-report access (private, invited, link, public), and a comment thread anchored to the paragraph someone has a question about (comment on HTML).

Nothing has to stay running. Close the laptop.

Try it

Comma is free — unlimited reports, unlimited commenters, unlimited revision history.

Publish a report →

http://localhost:8080 will never open for them