# Debug Tool

For advanced debugging and troubleshooting of journey planning queries, Entur provides the **OTP Debug Tool**.

**OTP Debug Tool:** [https://otpdebug.entur.org/](https://otpdebug.entur.org/)

## What is the OTP Debug Tool?

The OTP Debug Tool is a visual interface for inspecting and debugging the underlying [OpenTripPlanner](https://github.com/entur/opentripplanner) routing engine that powers Journey Planner. It allows you to interact directly with the routing graph and transit data used by the journey planning algorithm.

## What can you do with it?

-   **Visualize the routing graph** - Inspect the street and transit network that OpenTripPlanner uses for routing
-   **Explore stop locations** - Browse and search for stop places on the map
-   **Analyze transit data** - View timetable data, routes, and real-time feeds that are loaded into the search engine
-   **Debug routing results** - Understand why certain routes are or aren't being suggested for a given query
-   **Inspect journey details** - Examine the individual legs and transfers of a planned journey

## When to use it

The debug tool is particularly useful when:

-   A journey query returns unexpected results and you want to understand why
-   You need to verify that specific transit data or real-time updates are correctly loaded
-   You are investigating routing issues related to specific stops, routes, or geographic areas
-   You want to understand how the [RAPTOR algorithm](/docs/open-services/journey-planner#the-algorithm-for-finding-the-optimal-path) evaluates different journey options

## GraphQL Explorer

For testing and building API queries, use the **GraphQL Explorer** instead:

**GraphQL IDE:** [https://api.entur.io/graphql-explorer/journey-planner-v3](https://api.entur.io/graphql-explorer/journey-planner-v3)

The GraphQL Explorer lets you write and execute queries against the Journey Planner API, with auto-completion and built-in documentation of the schema. See [Examples](/docs/open-services/journey-planner/examples) for pre-built example queries you can try.