Why is telemetry collected?

Next.js has grown considerably since its release, becoming the de-facto React Framework for developers. Prior to telemetry collection, making decisions about how to improve Next.js was a very manual process.

For example, Verceldogfoods many large React applications (including the Next.js website). Additionally, we actively engage with the community to gather feedback.

However, this approach only allows us to collect feedback from a subset of users. This subset may have different needs and use cases than you. Telemetry allows us to accurately gauge Next.js feature usage, pain points, and customization.

This data will let us better tailor Next.js to the masses, ensuring its continued growth, relevance, and best-in-class developer experience. Furthermore, this will allow us to verify if improvements made to the framework are improving the baseline of all applications.

What is being collected?

We track general usage information, such as Next.js plugins and build performance.Specifically, we track the following anonymously:

• Command invoked (next build,next dev, ornext export)
• Version of Next.js
• General machine information (e.g. number of CPUs, macOS/Windows/Linux, whether or not the command was run within CI)
• What Next.js plugins are present in your project
• Duration ofnext build and size of application (total number of pages)
• During development, we ask for additional feedback on errors (seeError Feedback)

Note: This list is regularly audited to ensure its accuracy.

You can view exactly what is being collected by setting the following environment variable:NEXT_TELEMETRY_DEBUG=1.

When this environment variable is set, data willnot be sent to us.The data will only be printed out to thestderr stream, prefixed with[telemetry].

An example telemetry event looks like this:

{"eventName":"NEXT_VERSION","payload": {"version":"9.0.5-canary.2","isDevelopment":false  }}

What about sensitive data (e.g. secrets)?

Wedo not collect any metrics which may contain sensitive data.

This includes, but is not limited to: environment variables, file paths, contents of files, logs, or serialized JavaScript errors.

We take privacy and our security very seriously. Next.js telemetry falls under thesecurity disclosure policy.

The data we collect is also completely anonymous, not traceable to the source, and only meaningful in aggregate form.

No data we collect is personally identifiable.

Will this data be shared?

We use telemetry data internally to help us improve the product and will only share de-identified data in the aggregate for business purposes such as marketing.

Error Feedback

When an error is displayed during development, Next.js allows sending feedback whether the error was helpful or not.This feedback is sent to Vercel and is used to improve the error messages in Next.js.Next.js will not automatically collect this feedback.Developers must click the thumbs up or down buttons to send the corresponding feedback.

Next.js will only collect an error code and any other information it already automatically collects.The error code is a unique identifier for a particular error.The full error message cannot be reconstructed from this code since the error message may contain app-specific data like the page the error occured in.A list of error codes and their corresponding messages is available atvercel/next.js/packages/next/errors.json.

How do I opt-out?

You may opt out-by runningnext telemetry disable in the root of your project directory:

npxnexttelemetrydisable

yarnnexttelemetrydisable

pnpmexecnexttelemetrydisable

bunnexttelemetrydisable

You may check the status of telemetry collection at any time by runningnext telemetry status in the root of your project directory:

npxnexttelemetrystatus

yarnnexttelemetrystatus

pnpmexecnexttelemetrystatus

bunnexttelemetrystatus

You may re-enable telemetry if you'd like to re-join the program by running the following in the root of your project directory:

npxnexttelemetryenable

yarnnexttelemetryenable

pnpmexecnexttelemetryenable

bunnexttelemetryenable

You may also opt-out by setting an environment variable:NEXT_TELEMETRY_DISABLED=1.