HTTP Archive (HAR) v1.2

Data Structure

HAR files are required to be saved in UTF-8 encoding, other encodings are forbidden. The spec requires that tools support and ignore a BOM and allow them to emit one if they like.

Summary of HAR object types:

log
- creator
- browser
- pages
  - pageTimings
- entries
  - request
    - headers
    - cookies
    - queryString
    - postData
      - params
  - response
    - headers
    - cookies
    - content
  - cache
  - timings

log

This object represents the root of exported data.

"log": {
  "version" : "1.2",
  "creator" : {},
  "browser" : {},
  "pages": [],
  "entries": [],
  "comment": ""
}

name	type	required	default	description
version	`string`	✔️	`1.2`	Version number of the format
creator	`object`	✔️	`N/A`	Name and version info of the log creator application
browser	`object`	✖️	`N/A`	Name and version info of used browser
pages	`array`	✖️	`N/A`	List of all exported (tracked) pages
entries	`array`	✔️	`N/A`	List of all exported (tracked) requests
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

There is one page object for every exported web page and one entry object for every HTTP request. In case when an HTTP trace tool isn't able to group requests by a page, the pages array is empty and individual requests doesn't have a parent page.

creator

"creator": {
  "name": "Firebug",
  "version": "1.6",
  "comment": ""
}

name	type	required	default	description
name	`string`	✔️	`N/A`	Name of the application used to export the log
version	`string`	✔️	`N/A`	Version of the application used to export the log
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

browser

"browser": {
  "name": "Firefox",
  "version": "3.6",
  "comment": ""
}

name	type	required	default	description
name	`string`	✔️	`N/A`	Name of the browser used to export the log
version	`string`	✔️	`N/A`	Version of the browser used to export the log
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

pages

This object represents list of exported pages.

"pages": [
  {
    "startedDateTime": "2009-04-16T12:07:25.123+01:00",
    "id": "page_0",
    "title": "Test Page",
    "pageTimings": {},
    "comment": ""
  }
]

name	type	required	default	description
startedDateTime	`string`	✔️	`N/A`	Date and time stamp for the beginning of the page load (`ISO 8601`)
id	`string`	✔️	`N/A`	Unique identifier of a page within the `log`. `Entries` use it to refer the parent page
title	`string`	✔️	`N/A`	Page title
pageTimings	`object`	✔️	`N/A`	Detailed timing info about page load
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

pageTimings

This object describes timings for various events (states) fired during the page load. All times are specified in milliseconds. If a time info is not available appropriate field is set to -1

"pageTimings": {
  "onContentLoad": 1720,
  "onLoad": 2500,
  "comment": ""
}

name	type	required	default	description
onContentLoad	`number`	✖️	`-1`	Content of the page loaded. Number of milliseconds since page load started (`page.startedDateTime`)
onLoad	`number`	✖️	`-1`	Page is loaded (`onLoad` event fired). Number of milliseconds since page load started (`page.startedDateTime`)
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

Depeding on the browser, onContentLoad property represents DOMContentLoad event or document.readyState == interactive.

entries

This object represents an array with all exported HTTP requests. Sorting entries by startedDateTime (starting from the oldest) is preferred way how to export data since it can make importing faster. However the reader application should always make sure the array is sorted (if required for the import).

"entries": [
  {
    "pageref": "page_0",
    "startedDateTime": "2009-04-16T12:07:23.596Z",
    "time": 50,
    "request": {},
    "response": {},
    "cache": {},
    "timings": {},
    "serverIPAddress": "10.0.0.1",
    "connection": "52492",
    "comment": ""
  }
]

name	type	required	default	description
pageref	`string`	✖️	`N/A`	Unique Reference to the parent page
startedDateTime	`string`	✔️	`N/A`	Date and time stamp of the request start (`ISO 8601`)
time	`number`	✔️	`0`	Total elapsed time of the request in milliseconds. This is the sum of all timings available in the timings object (i.e. not including `-1` values)
request	`object`	✔️	`N/A`	Detailed info about the request
response	`object`	✔️	`N/A`	Detailed info about the response
cache	`object`	✔️	`N/A`	Info about cache usage
timings	`object`	✔️	`N/A`	Detailed timing info about request/response round trip
serverIPAddress	`string`	✖️	`N/A`	(new in 1.2) - IP address of the server that was connected (result of DNS resolution)
connection	`string`	✖️	`N/A`	(new in 1.2) - Unique ID of the parent TCP/IP connection, can be the client or server port number.
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

connection: Note that a port number doesn't have to be unique identifier in cases where the port is shared for more connections. If the port isn't available for the application, any other unique connection ID can be used instead (e.g. connection index)

request

This object contains detailed info about performed request.

"request": {
  "method": "GET",
  "url": "http://www.example.com/path/?param=value",
  "httpVersion": "HTTP/1.1",
  "cookies": [],
  "headers": [],
  "queryString" : [],
  "postData" : {},
  "headersSize" : 150,
  "bodySize" : 0,
  "comment" : ""
}

name	type	required	default	description
method	`string`	✔️	`N/A`	Request method
url	`string`	✔️	`N/A`	Absolute URL of the request (fragments are not included)
httpVersion	`string`	✔️	`N/A`	Request HTTP Version
cookies	`array`	✔️	`N/A`	List of `cookie` objects
headers	`array`	✔️	`N/A`	List of `header` objects
queryString	`array`	✔️	`N/A`	List of query parameter objects
postData	`object`	✖️	`N/A`	Posted data info
headersSize	`number`	✔️	`-1`	Total number of bytes from the start of the HTTP request message until (and including) the double `CRLF` before the body
bodySize	`number`	✔️	`-1`	Size of the request body in bytes (e.g. `POST` data payload)
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

The total request size sent can be computed as follows (if both values are available):
let totalSize = entry.request.headersSize + entry.request.bodySize

response

This object contains detailed info about the response.

"response": {
  "status": 200,
  "statusText": "OK",
  "httpVersion": "HTTP/1.1",
  "cookies": [],
  "headers": [],
  "content": {},
  "redirectURL": "",
  "headersSize" : 160,
  "bodySize" : 850,
  "comment" : ""
}

name	type	required	default	description
status	`number`	✔️	`N/A`	Response status
statusText	`string`	✔️	`N/A`	Response status description
httpVersion	`string`	✔️	`N/A`	Response HTTP Version
cookies	`array`	✔️	`N/A`	List of `cookie` objects
headers	`array`	✔️	`N/A`	List of `header` objects
content	`object`	✔️	`N/A`	Details about the response body
redirectURL	`string`	✔️	`N/A`	Redirection target URL from the Location response header
headersSize	`number`	✔️	`-1`	Total number of bytes from the start of the HTTP response message until (and including) the double `CRLF` before the body
bodySize	`number`	✔️	`-1`	Size of the received response body in bytes. Set to `0` in case of responses coming from the cache (`304`)
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

headersSize: The size of received response-headers is computed only from headers that are really received from the server. Additional headers appended by the browser are not included in this number, but they appear in the list of header objects.

The total response size received can be computed as follows (if both values are available):
let totalSize = entry.response.headersSize + entry.response.bodySize

cookies

This object contains list of all cookies (used in request and response objects).

"cookies": [
  {
    "name": "TestCookie",
    "value": "Cookie Value",
    "path": "/",
    "domain": "www.janodvarko.cz",
    "expires": "2009-07-24T19:20:30.123+02:00",
    "httpOnly": false,
    "secure": false,
    "comment": ""
  }
]

name	type	required	default	description
name	`string`	✔️	`N/A`	The name of the cookie
value	`string`	✔️	`N/A`	The cookie value
path	`string`	✖️	`N/A`	The path pertaining to the cookie
domain	`string`	✖️	`N/A`	The host of the cookie
expires	`string`	✖️	`N/A`	Cookie expiration time. (`ISO 8601`)
httpOnly	`boolean`	✖️	`N/A`	Set to true if the cookie is HTTP only, false otherwise
secure	`boolean`	✖️	`N/A`	(new in 1.2) - `true` if the cookie was transmitted over ssl, `false` otherwise
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

headers

This object contains list of all headers (used in request and response objects).

"headers": [
  {
    "name": "Accept-Encoding",
    "value": "gzip,deflate",
    "comment": ""
  },
  {
    "name": "Accept-Language",
    "value": "en-us,en;q=0.5",
    "comment": ""
  }
]

name	type	required	default	description
name	`string`	✔️	`N/A`	The name of the header
value	`string`	✔️	`N/A`	The header value
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

queryString

This object contains list of all parameters & values parsed from a query string, if any (embedded in request object).

"queryString": [
  {
    "name": "param1",
    "value": "value1",
    "comment": ""
  },
  {
    "name": "param1",
    "value": "value1",
    "comment": ""
  }
]

name	type	required	default	description
name	`string`	✔️	`N/A`	The name of the query
value	`string`	✔️	`N/A`	The query value
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

postData

This object describes posted data, if any (embedded in request object).

"postData": {
  "mimeType": "multipart/form-data",
  "params": [],
  "text" : "plain posted data",
  "comment": ""
}

name	type	required	default	description
mimeType	`string`	✔️	`N/A`	Mime type of posted data
params	`array`	✔️*	`N/A`	List of posted parameters (in case of URL encoded parameters)
text	`string`	✔️*	`N/A`	Plain text posted data
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

text and params fields are mutually exclusive.

params

List of posted parameters, if any (embedded in postData object).

"params": [
  {
    "name": "paramName",
    "value": "paramValue",
    "fileName": "example.pdf",
    "contentType": "application/pdf",
    "comment": ""
  }
]

name	type	required	default	description
name	`string`	✔️	`N/A`	name of a posted parameter
value	`string`	✖️	`N/A`	value of a posted parameter or content of a posted file
fileName	`string`	✖️	`N/A`	name of a posted file
contentType	`string`	✖️	`N/A`	content type of a posted file
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

content

This object describes details about response content (embedded in response object).

"content": {
  "size": 33,
  "compression": 0,
  "mimeType": "text/html; charset=utf-8",
  "text": "\n",
  "comment": ""
}

name	type	required	default	description
size	`number`	✔️	`N/A`	Length of the returned content in bytes. Should be equal to `response.bodySize` if there is no compression and bigger when the content has been compressed
compression	`number`	✖️	`N/A`	Number of bytes saved
mimeType	`string`	✔️	`N/A`	MIME type of the response `text` (value of the `Content-Type` response header). The charset attribute of the MIME type is included (if available)
text	`string`	✖️	`N/A`	Response body sent from the server or loaded from the browser cache.
encoding	`string`	✖️	`N/A`	(new in 1.2) - Encoding used for response `text` field e.g "base64"
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

The text field is populated with textual content only

The text field is either HTTP decoded text or a encoded (e.g. "base64") representation of the response body

Leave out the encoding field if the text field is HTTP decoded (decompressed & unchunked), than trans-coded from its original character set into UTF-8

Before setting the text field, the HTTP response is decoded (decompressed & unchunked), than trans-coded from its original character set into UTF-8.

Additionally, it can be encoded using e.g. base64.

Ideally, the application should be able to unencode a base64 blob and get a byte-for-byte identical resource to what the browser operated on.

encoding field is useful for including binary responses (e.g. images) into the HAR file.

Example

original

<html><head></head><body/></html>\n

encoded

"content": {
  "size": 33,
  "compression": 0,
  "mimeType": "text/html; charset=utf-8",
  "text": "PGh0bWw+PGhlYWQ+PC9oZWFkPjxib2R5Lz48L2h0bWw+XG4=",
  "encoding": "base64",
  "comment": ""
}

cache

This objects contains info about a request coming from browser cache.

"cache": {
  "beforeRequest": {},
  "afterRequest": {},
  "comment": ""
}

name	type	required	default	description
beforeRequest	`object`	✖️	`N/A`	State of a cache entry before the request
afterRequest	`object`	✖️	`N/A`	State of a cache entry after the request
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

Example 1

No cache information are available (or you can just leave out the entire field).

"cache": {}

Example 2

Info about the cache entry before request is not available and there is no cache entry after the request.

"cache": {
  "afterRequest": null
}

Example 3

No cache entry before nor after the request.

"cache": {
  "beforeRequest": null,
  "afterRequest": null
}

Example 4

Indicate that the entry was not in the cache but was store after the content was downloaded by the request.

"cache": {
  "beforeRequest": null,
  "afterRequest": {
    "expires": "2009-04-16T15:50:36",
    "lastAccess": "2009-16-02T15:50:34",
    "eTag": "",
    "hitCount": 0,
    "comment": ""
  }
}

beforeRequest / afterRequest

"beforeRequest": {
  "expires": "2009-04-16T15:50:36",
  "lastAccess": "2009-16-02T15:50:34",
  "eTag": "",
  "hitCount": 0,
  "comment": ""
}

name	type	required	default	description
expires	`string`	✖️	`N/A`	Expiration time of the cache entry
lastAccess	`string`	✔️	`N/A`	The last time the cache entry was opened
eTag	`string`	✔️	`N/A`	Etag
hitCount	`number`	✔️	`N/A`	The number of times the cache entry has been opened
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

timings

This object describes various phases within request-response round trip. All times are specified in milliseconds.

"timings": {
  "blocked": 0,
  "dns": -1,
  "connect": 15,
  "send": 20,
  "wait": 38,
  "receive": 12,
  "ssl": -1,
  "comment": ""
}

name	type	required	default	description
blocked	`number`	✖️	`-1`	Time spent in a queue waiting for a network connection
dns	`number`	✖️	`-1`	DNS resolution time. The time required to resolve a host name
connect	`number`	✖️	`-1`	Time required to create TCP connection
send	`number`	✔️	`N/A`	Time required to send HTTP request to the server
wait	`number`	✔️	`N/A`	Waiting for a response from the server
receive	`number`	✔️	`N/A`	Time required to read entire response from the server (or cache)
ssl	`number`	✖️	`-1`	(new in 1.2) - Time required for SSL/TLS negotiation.
comment	`string`	✖️	`N/A`	(new in 1.2) - A comment provided by the user or the application

If the ssl field is defined then the time is also included in the connect field (to ensure backward compatibility with HAR v1.1)

The send, wait and receive timings are not optional and must have non-negative values.

An exporting tool can omit the blocked, dns, connect and ssl, timings on every request if it is unable to provide them.

Tools that can provide these timings can set their values to -1 if they don’t apply. For example, connect would be -1 for requests which re-use an existing connection.

The time value for the request must be equal to the sum of the timings supplied in this section (excluding any -1 values).

The Following must be true in case there are no -1 values (entry is an object in log.entries) :
entry.time == entry.timings.blocked + entry.timings.dns + entry.timings.connect
              entry.timings.send + entry.timings.wait + entry.timings.receive

Custom Fields

The specification allows adding new custom fields into the output format. Following rules must be applied:

Custom fields and elements MUST start with an underscore (spec fields should never start with an underscore.
Parsers MUST ignore all custom fields and elements if the file was not written by the same tool loading the file.
Parsers MUST ignore all non-custom fields that they don't know how to parse because the minor version number is greater than the maximum minor version for which they were written.
Parsers can reject files that contain non-custom fields that they know were not present in a specific version of the spec.

Versioning Scheme

The spec number has following syntax:

<major-version-number>.<minor-version-number>

Where the major version indicates overall backwards compatibility and the minor version indicates incremental changes. So, any backwardly compatible changes to the spec will result in an increase of the minor version. If an existing fields had to be broken then major version would increase (e.g. 2.0).

Examples:

1.2 -> 1.3
1.111 -> 1.112 (in case of 111 more changes)
1.5 -> 2.0 (2.0 is not compatible with 1.5)

So following construct can be used to detect incompatible version if a tool supports HAR since 1.1.

if (majorVersion != 1 || minorVersion < 1)
{
  throw "Incompatible version"
}

In this example a tool throws an exception if the version is e.g.: 0.8, 0.9, 1.0, but works with 1.1, 1.2, 1.112 etc. Version 2.x would be rejected.

HAR Compression

Compression of the HAR file is not part of the core HAR spec. However, in order to store HAR files more efficiently, it is recommended that you compress HAR files on disk (you might want to use *.zhar extension for zipped HAR files).

An application supporting HAR, is not required to support compressed HAR files. If the application doesn't support compressed HAR then it's the responsibility of the user to decompress before passing the HAR file into it.

HTTP Compression is one of the best practices how to speed up web applications and it's also recommended for HAR files.

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HTTP Archive (HAR) v1.2

Data Structure

log

creator

browser

pages

pageTimings

entries

request

response

cookies

headers

queryString

postData

params

content

Example

cache

Example 1

Example 2

Example 3

Example 4

beforeRequest / afterRequest

timings

Custom Fields

Versioning Scheme

Examples:

HAR Compression

FilesExpand file tree

1.2.md

Latest commit

History

1.2.md

File metadata and controls

HTTP Archive (HAR) v1.2

Data Structure

log

creator

browser

pages

pageTimings

entries

request

response

cookies

headers

queryString

postData

params

content

Example

cache

Example 1

Example 2

Example 3

Example 4

beforeRequest / afterRequest

timings

Custom Fields

Versioning Scheme

Examples:

HAR Compression