DevTools Protocol

This page specifies the Inertia DevTools protocol. The DevTools page gives a high-level overview of the feature. The DevTools extension works with any backend, and any server-side Inertia adapter may integrate with it by implementing this protocol. The Laravel adapter is the reference implementation, and nothing in this specification depends on Laravel. The protocol has three layers:

Discovery: how the extension learns that the adapter recorded an entry.
Correlation headers: the request and response headers that link entries and group them.
Read API: the endpoints that return recorded entries, and the format of those entries.

While recording is enabled, a conforming adapter records one entry for each request it handles. It stores the entry under a generated id, separately for each browser tab, and returns it through the read API. The extension fetches each entry in a separate request. Recording adds discovery headers to each response and a discovery script to the initial HTML response, but the entry itself never appears in the application’s response.

Discovery

For every response, the adapter generates a unique entry id and sets it on a response header. The id may be any collision-resistant string of 1 to 256 characters, such as a ULID.

string

The generated id of the entry, set on every response. The extension reads the id from this header, then fetches the entry from the read API.

The extension reads the id from the response header through a browser request listener. On the initial full-page HTML response, the adapter also adds a script element that holds the id. The extension’s content script reads the id from that script after the document loads.

<script data-inertia-devtools-id type="application/json">"<id>"</script>

The script contains the id as a JSON-encoded string. An application served from a subpath, such as /admin, needs one more value. The extension sends read API requests to that subpath, so the adapter reports it.

string

The path the application is served from, such as /admin. The adapter sets it only when the application is not served from the root of its origin. The adapter also adds the value to the discovery script as a data-inertia-devtools-base-path attribute.

Correlation Headers

The correlation headers link entries to client-side page state and group related requests. The extension sets the request headers, and the adapter stores their values on the entry. The adapter sets the response header. The extension sends the following request headers. Each header is optional.

string

A UUID for the browser tab, stored as __meta.tabUuid. The adapter stores entries separately for each tab, so one tab’s history does not evict another tab’s history.

string

The client’s visit id, stored as __meta.visitId. The extension uses it to pair the entry with the page snapshot it took in the browser.

string

The id of the entry that started the batch, stored as __meta.batchId. The adapter stores the value unchanged. The client handles grouping.

string

Set to 1 on the follow-up request for deferred props. The request is otherwise identical to a partial reload, so the client marks it with this header.

string

Set to 1 on a polling request. A polling request is otherwise identical to a partial reload as well.

The adapter sets the following response header.

string

The id of the batch root. The batch root is the batchId of the request, or the entry’s own id when the request starts a batch. The client sends this value as X-Inertia-Devtools-Parent on its next follow-up request, such as a partial reload, a deferred props request, or a polling request. Every follow-up request then points at the root, which keeps the batch flat. A full navigation sends no parent header and starts a new batch, so a redirect and its target appear as separate roots. A prefetch response returns its own id instead. The user may never visit a prefetched page, so a prefetch must not change the batch root for other requests.

The adapter sets this header on every response. Without it, the client uses the response’s X-Inertia-Devtools-Id as the next parent. Each follow-up request then attaches to the previous response instead of the batch root.

The Read API

The read API has two endpoints at fixed paths below the application’s base path. The adapter allows access to them only in development or for an authorized developer. GET /_inertia/devtools/entries/{id} returns one entry as JSON, or a 404 response for an unknown id. The extension calls only this endpoint. It reads an id from the discovery script or the response header, then fetches that entry. GET /_inertia/devtools/entries returns a JSON array of entry summaries, newest first. Each summary is the entry’s __meta object. The extension does not call this endpoint, so it is optional. It serves tools that list a tab’s history. An adapter may support the following optional query parameters:

component: keep only entries for this exact component name.
type: keep only entries with these request types, as a comma-separated list.
exclude: drop entries with these request types, as a comma-separated list.
offset and limit: page through the results.

A minimal adapter may ignore the parameters and return the summary of every stored entry. The extension sends same-origin cookies with each request, so the adapter may authorize it.

The Entry Format

An entry is a JSON object with required and optional fields. The panel needs every required field, so for a value that does not exist, the adapter emits the documented empty form or null instead of leaving the key out. Optional fields add detail. An adapter may leave an optional field out, or emit null where the field’s type allows it. The propValues map may also be {}. The panel still works with less detail. For example, it hides “open in editor” links when source locations are missing. An adapter may add fields beyond this specification. The extension ignores unknown fields instead of rejecting the entry. A fully populated entry for a standard navigation looks like this.

{
    "__meta": {
        "id": "01ARZ3NDEKTSV4RRFFQ69G5FAV",
        "tabUuid": "123e4567-e89b-42d3-a456-426614174000",
        "batchId": null,
        "timestamp": "2026-07-09T10:00:00.123Z",
        "utime": 1783591200.123,
        "method": "GET",
        "url": "http://localhost/users",
        "component": "Users/Index",
        "requestType": "navigate",
        "status": 200,
        "redirectLocation": null,
        "serverTimingMs": 12.5,
        "visitId": "visit-1"
    },
    "http": {
        "requestHeaders": { "x-inertia": "true" },
        "responseHeaders": { "content-type": "application/json" },
        "requestBody": { "status": "empty" },
        "responseBody": {
            "status": "present",
            "value": {
                "component": "Users/Index",
                "props": { "name": "Alice" },
                "flash": { "message": "User created" }
            }
        }
    },
    "props": {
        "name": { "shared": false },
        "errors": { "inertiaType": "always", "shared": true, "shareSource": { "file": "Middleware.php", "line": 72 } }
    },
    "propValues": { "name": "Alice", "errors": {} },
    "route": {
        "name": "users.index",
        "uri": "/users",
        "action": "App\\Http\\Controllers\\UsersController@index",
        "actionSource": { "file": "UsersController.php", "line": 15 }
    },
    "renderSource": { "file": "UsersController.php", "line": 17 },
    "componentPath": "resources/js/Pages/Users/Index.vue"
}

The following sections describe each field.

HTTP

The http object and each of its keys are required. With nothing to show, the adapter emits the empty form.

http: {
    requestHeaders:  Record<string, string>   // may be {}
    responseHeaders: Record<string, string>   // may be {}
    requestBody:     BodyCapture
    responseBody:    BodyCapture
}

BodyCapture is a tagged union.

| { status: 'empty' }
| { status: 'present', value: <json tree or raw string> }
| { status: 'omitted', reason: string }

value is a string for a raw text body. For structured data, such as parsed JSON or form input, it is a JSON-compatible value. The panel recognizes the following omitted reasons: non-inertia-response, non-inertia-request, non-textual, streamed, too-large, unserializable, and binary. It shows a readable notice for each one, and a generic message for an unknown reason, so an adapter may add new reasons. An adapter should redact sensitive keys and summarize file uploads instead of serializing binary content.

Props

Record<string, PropMeta>

required

Metadata for each prop, keyed by dotted path. The panel builds its prop tree from this map and adds intermediate nodes for dotted paths. A listed prop without metadata children shows its nested values from propValues, so those nested paths need no entries of their own. A prop with metadata children shows the child rows instead. An adapter that cannot classify a top-level prop still lists it, with empty metadata. With props set to {}, the panel shows no props, even when propValues contains values.

Show PropMeta

Every field is optional. Source locations are { file: string, line: number }.

boolean

Whether the prop path matches a top-level shared key. A page prop with the same key overrides the shared value, but the Laravel adapter still marks the path as shared.

string

boolean

Set for a once prop. The client reuses its value on later visits until the value expires or the server refreshes it.

boolean

Set for a live prop. The client refreshes it whenever one of its broadcast events arrives.

'append' | 'prepend'

How a merge or scroll prop combines with existing client data.

boolean

Set alongside mergeDirection for a deep merge.

boolean

Set for a deferred prop that threw and that the adapter rescued. The prop has no value in this response.

{ file, line }

Record<string, unknown>

The resolved prop values, keyed by dotted path. The adapter replaces sensitive values with "[REDACTED]". It may leave the field out or send {}, and the panel handles both.

Route

string

required

The matched route path, or "" when no route matched.

string | null

required

The route name, or null for an unnamed route.

string | null

required

The controller or handler identifier, or null when none applies.

{ file, line }

The source location of the handler.

{ file, line } | null

required

The source location of the render call, or null when the adapter cannot resolve it.

string | null

required

The path of the component file, or null when the adapter cannot resolve it.

The source location fields provide the “open in editor” links. An adapter that cannot resolve them cheaply emits null and loses only those links.

Request Type Derivation

The adapter derives the request type from the request headers, including the two DevTools hint headers. It checks the following conditions in order and uses the first match.

Order	Condition	Request type
1	The Precognition header is present	`precognition`
2	Not an Inertia request, and the adapter rendered an Inertia page	`initial`
3	Not an Inertia request, and the adapter rendered no Inertia page	`http`
4	`X-Inertia-Devtools-Deferred` is present	`deferred`
5	`X-Inertia-Devtools-Poll` is present	`poll`
6	`X-Inertia-Partial-Component` is present	`partial`
7	`Purpose: prefetch` is present	`prefetch`
8	None of the above	`navigate`

initial and http are both non-Inertia requests. The adapter tells them apart by whether it rendered an Inertia page. The application’s initial full-page load renders a page, so its component is set and its type is initial. A plain JSON or text endpoint that the application serves next to Inertia renders no page, so its component is null and its type is http. The adapter knows which kind of response it produced, so it sets the type instead of leaving the panel to work it out. The client-visit and cache-hit types are client-only and never come from an adapter.

Storage Semantics

An adapter keeps recent entries and evicts old ones. It usually limits the number of entries for each tabUuid, so a busy tab cannot evict another tab’s history. It also removes entries older than a time limit. The adapter chooses these limits. The protocol requires only that the read API return the stored entries, newest first.

Getting Started

Installation

Core Concepts

The Basics

Data & Props

Security

Advanced

Server Adapters

Discovery

Correlation Headers

The Read API

The Entry Format

Meta

HTTP

Props

Route

Request Type Derivation

Storage Semantics