For the latest stable version, please use Spring Boot 4.0.1!

Application Startup (startup)

The startup endpoint provides information about the application’s startup sequence.

Retrieving the Application Startup Steps

The application startup steps can either be retrieved as a snapshot (GET) or drained from the buffer (POST).

Retrieving a snapshot of the Application Startup Steps

To retrieve the steps recorded so far during the application startup phase, make a GET request to /actuator/startup, as shown in the following curl-based example:

$ curl 'http://localhost:8080/actuator/startup' -i -X GET

The resulting response is similar to the following:

HTTP/1.1 200 OK
Content-Type: application/vnd.spring-boot.actuator.v3+json
Content-Length: 890

{
  "springBootVersion" : "3.4.13",
  "timeline" : {
    "startTime" : "2025-12-18T07:13:26.071231143Z",
    "events" : [ {
      "endTime" : "2025-12-18T07:13:26.657897941Z",
      "duration" : "PT0.000006613S",
      "startTime" : "2025-12-18T07:13:26.657891328Z",
      "startupStep" : {
        "name" : "spring.beans.instantiate",
        "id" : 3,
        "tags" : [ {
          "key" : "beanName",
          "value" : "homeController"
        } ],
        "parentId" : 2
      }
    }, {
      "endTime" : "2025-12-18T07:13:26.657904212Z",
      "duration" : "PT0.000022071S",
      "startTime" : "2025-12-18T07:13:26.657882141Z",
      "startupStep" : {
        "name" : "spring.boot.application.starting",
        "id" : 2,
        "tags" : [ {
          "key" : "mainApplicationClass",
          "value" : "com.example.startup.StartupApplication"
        } ]
      }
    } ]
  }
}

Draining the Application Startup Steps

To drain and return the steps recorded so far during the application startup phase, make a POST request to /actuator/startup, as shown in the following curl-based example:

$ curl 'http://localhost:8080/actuator/startup' -i -X POST

The resulting response is similar to the following:

HTTP/1.1 200 OK
Content-Type: application/vnd.spring-boot.actuator.v3+json
Content-Length: 890

{
  "springBootVersion" : "3.4.13",
  "timeline" : {
    "startTime" : "2025-12-18T07:13:26.071231143Z",
    "events" : [ {
      "endTime" : "2025-12-18T07:13:26.573051399Z",
      "duration" : "PT0.000264666S",
      "startTime" : "2025-12-18T07:13:26.572786733Z",
      "startupStep" : {
        "name" : "spring.beans.instantiate",
        "id" : 1,
        "tags" : [ {
          "key" : "beanName",
          "value" : "homeController"
        } ],
        "parentId" : 0
      }
    }, {
      "endTime" : "2025-12-18T07:13:26.573081125Z",
      "duration" : "PT0.001350654S",
      "startTime" : "2025-12-18T07:13:26.571730471Z",
      "startupStep" : {
        "name" : "spring.boot.application.starting",
        "id" : 0,
        "tags" : [ {
          "key" : "mainApplicationClass",
          "value" : "com.example.startup.StartupApplication"
        } ]
      }
    } ]
  }
}

Response Structure

The response contains details of the application startup steps. The following table describes the structure of the response:

Path Type Description

springBootVersion

String

Spring Boot version for this application.

timeline.startTime

String

Start time of the application.

timeline.events

Array

An array of steps collected during application startup so far.

timeline.events.[].startTime

String

The timestamp of the start of this event.

timeline.events.[].endTime

String

The timestamp of the end of this event.

timeline.events.[].duration

String

The precise duration of this event.

timeline.events.[].startupStep.name

String

The name of the StartupStep.

timeline.events.[].startupStep.id

Number

The id of this StartupStep.

timeline.events.[].startupStep.parentId

Number

The parent id for this StartupStep.

timeline.events.[].startupStep.tags

Array

An array of key/value pairs with additional step info.

timeline.events.[].startupStep.tags[].key

String

The key of the StartupStep Tag.

timeline.events.[].startupStep.tags[].value

String

The value of the StartupStep Tag.