Question 1

how to integrate psi into a Gulp build process

Accepted Answer

Use the psi-gulp-sample project available on GitHub, which provides a working example. You can also install psi via npm and create custom tasks using the psi API to run performance tests during builds, as outlined in the common use cases.

Question 2

psi vs Lighthouse CLI for performance testing

Accepted Answer

psi is a wrapper for PageSpeed Insights, which runs tests on Google's servers and is ideal for deployed sites, while Lighthouse CLI runs audits locally for development. psi offers formatted reporting and build integration, but Lighthouse provides more control over local environments.

Question 3

how to get screenshot filmstrips from psi tests

Accepted Answer

Filmstrips are not available on the CLI; you need to use the psi API programmatically. Access them from the audits object in the response, as shown in the filmstrip example in the README, by calling data.lighthouseResult.audits['screenshot-thumbnails'].details.items.

Question 4

can psi test websites behind authentication

Accepted Answer

No, psi uses the public PageSpeed Insights API, which only tests publicly accessible URLs. For authenticated sites, you would need to deploy a publicly accessible version or use different tools like local Lighthouse runs.

Question 5

what API key do I need for psi in production

Accepted Answer

Register for an API key from the Google Developer Console, as recommended in the options section. The free tier is used by default, but a key is needed for higher usage to avoid rate limits and ensure reliability.

Question 6

how to set performance thresholds with psi in CI

Accepted Answer

Use the threshold option in the API or CLI, such as setting --threshold 80, to fail builds if scores are below that level. This enforces performance budgets, and you can integrate it into scripts using the psi output or data methods.

PSI

What is PSI?

Overview

Use Cases

Best For

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Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions