The reporting API

In this lesson, we'll study the reporting API.

In late 2018, Chrome rolled out a new feature to help web developers manage browser reports of exceptions. Amongst the issues that can be managed with the reporting API there are security ones, like CSP or feature-policy violations.

In a nutshell, the reporting API allows a website to advertise to the browser a particular URL it expects to receive reports to. With the Report-To header, a server can inform the browser to hand violations over at a particular URL.

Report-To: {
  "max_age": 86400,
  "endpoints": [{
    "url": ""

This API is still experimental so browser support is in the very early stages, but it’s an interesting tool to keep in mind in order to easily manage browser reports, and not just security ones. The reporting API can be used to receive information regarding multiple aspects of our users’ experience on our web application, such as:

  • CSP and feature-policy violations
  • risky code: the browser will sometimes intervene and block our code from performing a specific action as we’ve seen with CSP and the X-XSS-Protection headers
  • deprecations: when our application uses an API that the vendor is planning to deprecate
  • crashes: when our application has caused the client to crash

The reporting API is very useful and is not burdensome to implement. Consider adding it to your web app in order to make your job easier and get notified when exceptions happen on the client.


If setting up a URL that can capture browser reports isn’t feasible, consider using, a service that allows you to collect and analyze browser reports with a single line of code.

The service is free for up to ten thousand reports per month and is trusted by large organizations like the UK digital bank Monzo and the financial services provider Square Inc.

Testing your security posture

I want to conclude this chapter with a reference to, an incredibly useful website that allows you to verify that your web application has the correct security-related headers in place. After you submit a URL, you will be handed a grade and a breakdown, header by header. Here’s an example report for

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