> ## Documentation Index
> Fetch the complete documentation index at: https://docs.appsignal.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom instrumentation

> Where to add manual instrumentation when automatic tracing is not enough.

Automatic instrumentation gives AppSignal a strong starting point, but some
important work in your application is specific to your product. Custom
instrumentation helps you add spans, attributes, metadata, and error context in
the places that matter most to you.

Pick the guide that matches the SDK you use:

* [Ruby](/ruby/instrumentation)
* [Elixir](/elixir/instrumentation)
* [Node.js](/nodejs/3.x/instrumentation)
* [Front-end JavaScript](/front-end/span)
* [Python](/python/instrumentation)
* [Go](/go/custom-instrumentation)
* [Java](/java/custom-instrumentation)
* [PHP](/php/instrumentation)
* [OpenTelemetry](/opentelemetry/custom-instrumentation)

If you are extending OpenTelemetry setup specifically, also see [Add additional
OpenTelemetry Instrumentation](/guides/instrumentation/additional-opentelemetry-instrumentation).