# Share a WebPageTest Result — A Link That Won't Expire

Canonical: https://commareports.com/share-webpagetest-report
Published: 2026-09-14

> WebPageTest results age out of the public instance and private instances need a login. Export the run, publish it to Comma, and keep the filmstrip and waterfall at one URL.

# Share a WebPageTest result

A WebPageTest run is the best evidence there is for a performance argument, and
it is evidence with a shelf life. Public-instance results are pruned; a
self-hosted instance is behind a VPN and a login; and the link pasted into last
quarter's ticket now resolves to nothing at all — right when someone asks
whether the regression is new.

The data is recoverable while the run still exists. After that the argument is
somebody's memory of a number.

## Pull the run and build a page

```bash
# run it
npx webpagetest test https://example.com \
  --key "$WPT_API_KEY" --location "ec2-eu-west-1:Chrome" --runs 3 \
  --poll 5 --timeout 600 > result.json

# the pieces worth keeping
jq -r '.data.median.firstView |
  {TTFB, firstContentfulPaint, LargestContentfulPaint = .["chromeUserTiming.LargestContentfulPaint"],
   TotalBlockingTime, SpeedIndex}' result.json
```

The JSON also carries the URLs for the waterfall image, the filmstrip frames
and the connection view. Fetch those, put them in an HTML page with the metrics
table, and you have a self-contained record of the run.

## Publish it

Drop the page into [Comma](https://commareports.com/) — with the waterfall and
filmstrip images alongside it, so relative references are rewritten to the
uploaded copies and the page renders whole — or from CI:

```bash
curl -fsS -X PATCH "https://commareports.com/api/v1/reports/$REPORT_ID" \
  -H "Authorization: Bearer $COMMA_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d "$(jq -n --rawfile html wpt.html \
        --arg t "Perf — example.com — $(date -u +%F)" '{title: $t, html: $html}')"
```

Images go up through `POST /api/v1/reports/$REPORT_ID/assets` as base64. See
the [API reference](/docs/api) and [publishing from CI](/docs/ci). A
[routine](/features/routines) can run the whole thing on a schedule if there is
no pipeline to hang it off.

## Two audiences, one page

A performance report that only contains metrics loses the people who approve
the work, and one that only contains a filmstrip loses the people who do it.
Include both:

- **The filmstrip.** Non-engineers understand "the page is blank for 4.2
  seconds" instantly and understand an LCP number never.
- **The waterfall.** Engineers need the request that blocks, not the score.
- **The budget.** The numbers you agreed to, next to the numbers you got.

## A revision per run is the trend

PATCHing one saved report id makes the URL the standing performance page for
that page template. Each run appends a revision, so the regression question —
"was this always like this?" — is answered by scrubbing the history instead of
by re-running an experiment against a codebase that has since changed.

That is also the answer to the expiry problem: the retention policy becomes
yours.

## Comments where the request is

Performance work stalls on disagreement about cause. Anchored threads keep the
diagnosis on the evidence — "the 900ms is the font, not the API; we're
preloading it in #3310" — so the next person reads the conclusion rather than
re-deriving it from a screenshot. See [commenting on HTML](/comment-on-html).

## Limits

- **Entry HTML: 5 MB.** Assets: 25 MB per file, **250 MB and 500 files total**.
  A full filmstrip at 100ms intervals is a lot of frames — keep every 500ms, or
  the frames around the meaningful paint.
- **60 requests/minute per token.**

## Try it

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

**[Publish a performance report →](https://commareports.com/)**

### Related

- [Share a Lighthouse report](/share-lighthouse-report) · [Share an Unlighthouse report](/share-unlighthouse-report)
- [Share a sitespeed.io report](/share-sitespeed-report) · [Share a k6 load test report](/share-k6-load-test-report)
- [Share a Statoscope report](/share-statoscope-report) · [Expired CI artifacts](/fix/ci-artifact-expired)