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<form action="/en-US/search" class="search-form search-widget" id="top-nav-search-form" role="search"><label id="top-nav-search-label" for="top-nav-search-input" class="visually-hidden">Search MDN</label><input aria-activedescendant=""
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    placeholder="   " required="" value=""><button type="button" class="button action has-icon clear-search-button"><span class="button-wrap"><span class="icon icon-cancel "></span><span class="visually-hidden">Clear search
        input</span></span></button><button type="submit" class="button action has-icon search-button"><span class="button-wrap"><span class="icon icon-search "></span><span class="visually-hidden">Search</span></span></button>
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1. References
2. HTTP
3. Headers
4. User-Agent

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* English (US)
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IN THIS ARTICLE

* Syntax
* Firefox UA string
* Chrome UA string
* Opera UA string
* Microsoft Edge UA string
* Safari UA string
* Crawler and bot UA strings
* Library and net tool UA strings
* Specifications
* Browser compatibility
* See also

1. HTTP
2. Guides
3. Resources and URIs
1. Identifying resources on the Web
2. Data URLs
3. Introduction to MIME types
4. Common MIME types
5. Choosing between www and non-www URLs

4. HTTP guide
1. Basics of HTTP
2. Overview of HTTP
3. Evolution of HTTP
4. HTTP Messages
5. A typical HTTP session
6. Connection management in HTTP/1.x
7. Protocol upgrade mechanism

5. HTTP security
1. Content Security Policy (CSP)
2. HTTP Strict Transport Security (HSTS)
3. X-Content-Type-Options
4. X-Frame-Options
5. X-XSS-Protection
6. Practical security implementation guides
7. HTTP Observatory

6. HTTP access control (CORS)
7. HTTP authentication
8. HTTP caching
9. HTTP compression
10. HTTP conditional requests
11. HTTP content negotiation
12. HTTP cookies
13. HTTP range requests
14. HTTP redirects
15. HTTP specifications
16. Permissions Policy
17. References
18. HTTP headers
1. Accept
2. Accept-CH
3. Accept-Charset
4. Accept-Encoding
5. Accept-Language
6. Accept-Patch
7. Accept-Post
8. Accept-Ranges
9. Access-Control-Allow-Credentials
10. Access-Control-Allow-Headers
11. Access-Control-Allow-Methods
12. Access-Control-Allow-Origin
13. Access-Control-Expose-Headers
14. Access-Control-Max-Age
15. Access-Control-Request-Headers
16. Access-Control-Request-Method
17. Age
18. Allow
19. Alt-Svc
20. Alt-Used
21. Attribution-Reporting-Eligible Experimental
22. Attribution-Reporting-Register-Source Experimental
23. Attribution-Reporting-Register-Trigger Experimental
24. Authorization
25. Cache-Control
26. Clear-Site-Data
27. Connection
28. Content-Digest Experimental
29. Content-Disposition
30. Content-DPR Non-standard Deprecated
31. Content-Encoding
32. Content-Language
33. Content-Length
34. Content-Location
35. Content-Range
36. Content-Security-Policy
37. Content-Security-Policy-Report-Only
38. Content-Type
39. Cookie
40. Critical-CH Experimental
41. Cross-Origin-Embedder-Policy
42. Cross-Origin-Opener-Policy
43. Cross-Origin-Resource-Policy
44. Date
45. Device-Memory
46. Digest Non-standard Deprecated
47. DNT Non-standard Deprecated
48. Downlink Experimental
49. DPR Non-standard Deprecated
50. Early-Data Experimental
51. ECT Experimental
52. ETag
53. Expect
54. Expect-CT Deprecated
55. Expires
56. Forwarded
57. From
58. Host
59. If-Match
60. If-Modified-Since
61. If-None-Match
62. If-Range
63. If-Unmodified-Since
64. Keep-Alive
65. Last-Modified
66. Link
67. Location
68. Max-Forwards
69. NEL Experimental
70. No-Vary-Search Experimental
71. Observe-Browsing-Topics Experimental Non-standard
72. Origin
73. Origin-Agent-Cluster Experimental
74. Permissions-Policy
75. Pragma Deprecated
76. Priority
77. Proxy-Authenticate
78. Proxy-Authorization
79. Range
80. Referer
81. Referrer-Policy
82. Refresh
83. Report-To Non-standard Deprecated
84. Reporting-Endpoints Experimental
85. Repr-Digest Experimental
86. Retry-After
87. RTT Experimental
88. Save-Data Experimental
89. Sec-Browsing-Topics Experimental Non-standard
90. Sec-CH-Prefers-Color-Scheme Experimental
91. Sec-CH-Prefers-Reduced-Motion Experimental
92. Sec-CH-Prefers-Reduced-Transparency Experimental
93. Sec-CH-UA Experimental
94. Sec-CH-UA-Arch Experimental
95. Sec-CH-UA-Bitness Experimental
96. Sec-CH-UA-Full-Version Deprecated
97. Sec-CH-UA-Full-Version-List Experimental
98. Sec-CH-UA-Mobile Experimental
99. Sec-CH-UA-Model Experimental
100. Sec-CH-UA-Platform Experimental
101. Sec-CH-UA-Platform-Version Experimental
102. Sec-Fetch-Dest
103. Sec-Fetch-Mode
104. Sec-Fetch-Site
105. Sec-Fetch-User
106. Sec-GPC Experimental Non-standard
107. Sec-Purpose
108. Sec-WebSocket-Accept
109. Sec-WebSocket-Extensions
110. Sec-WebSocket-Key
111. Sec-WebSocket-Protocol
112. Sec-WebSocket-Version
113. Server
114. Server-Timing
115. Service-Worker-Navigation-Preload
116. Set-Cookie
117. Set-Login Experimental
118. SourceMap
119. Speculation-Rules Experimental
120. Strict-Transport-Security
121. Supports-Loading-Mode Experimental
122. TE
123. Timing-Allow-Origin
124. Tk Non-standard Deprecated
125. Trailer
126. Transfer-Encoding
127. Upgrade
128. Upgrade-Insecure-Requests
129. User-Agent
130. Vary
131. Via
132. Viewport-Width Non-standard Deprecated
133. Want-Content-Digest Experimental
134. Want-Digest Non-standard Deprecated
135. Want-Repr-Digest Experimental
136. Warning Deprecated
137. Width Non-standard Deprecated
138. WWW-Authenticate
139. X-Content-Type-Options
140. X-DNS-Prefetch-Control Non-standard
141. X-Forwarded-For Non-standard
142. X-Forwarded-Host Non-standard
143. X-Forwarded-Proto Non-standard
144. X-Frame-Options
145. X-XSS-Protection Non-standard

19. HTTP request methods
1. CONNECT
2. DELETE
3. GET
4. HEAD
5. OPTIONS
6. PATCH
7. POST
8. PUT
9. TRACE

20. HTTP response status codes
1. 100 Continue
2. 101 Switching Protocols
3. 102 Processing
4. 103 Early Hints
5. 200 OK
6. 201 Created
7. 202 Accepted
8. 203 Non-Authoritative Information
9. 204 No Content
10. 205 Reset Content
11. 206 Partial Content
12. 207 Multi-Status
13. 208 Already Reported
14. 226 IM Used
15. 300 Multiple Choices
16. 301 Moved Permanently
17. 302 Found
18. 303 See Other
19. 304 Not Modified
20. 307 Temporary Redirect
21. 308 Permanent Redirect
22. 400 Bad Request
23. 401 Unauthorized
24. 402 Payment Required
25. 403 Forbidden
26. 404 Not Found
27. 405 Method Not Allowed
28. 406 Not Acceptable
29. 407 Proxy Authentication Required
30. 408 Request Timeout
31. 409 Conflict
32. 410 Gone
33. 411 Length Required
34. 412 Precondition Failed
35. 413 Content Too Large
36. 414 URI Too Long
37. 415 Unsupported Media Type
38. 416 Range Not Satisfiable
39. 417 Expectation Failed
40. 418 I'm a teapot
41. 421 Misdirected Request
42. 422 Unprocessable Content
43. 423 Locked
44. 424 Failed Dependency
45. 425 Too Early
46. 426 Upgrade Required
47. 428 Precondition Required
48. 429 Too Many Requests
49. 431 Request Header Fields Too Large
50. 451 Unavailable For Legal Reasons
51. 500 Internal Server Error
52. 501 Not Implemented
53. 502 Bad Gateway
54. 503 Service Unavailable
55. 504 Gateway Timeout
56. 505 HTTP Version Not Supported
57. 506 Variant Also Negotiates
58. 507 Insufficient Storage
59. 508 Loop Detected
60. 510 Not Extended
61. 511 Network Authentication Required

21. CSP directives
1. CSP source values
2. CSP: base-uri
3. CSP: block-all-mixed-content Deprecated
4. CSP: child-src
5. CSP: connect-src
6. CSP: default-src
7. CSP: fenced-frame-src Experimental
8. CSP: font-src
9. CSP: form-action
10. CSP: frame-ancestors
11. CSP: frame-src
12. CSP: img-src
13. CSP: manifest-src
14. CSP: media-src
15. CSP: object-src
16. CSP: prefetch-src Non-standard Deprecated
17. CSP: report-to
18. CSP: report-uri Deprecated
19. CSP: require-trusted-types-for Experimental
20. CSP: sandbox
21. CSP: script-src
22. CSP: script-src-attr
23. CSP: script-src-elem
24. CSP: style-src
25. CSP: style-src-attr
26. CSP: style-src-elem
27. CSP: trusted-types Experimental
28. CSP: upgrade-insecure-requests
29. CSP: worker-src

22. CORS errors
1. Reason: CORS disabled
2. Reason: CORS header 'Access-Control-Allow-Origin' does not match 'xyz'
3. Reason: CORS header 'Access-Control-Allow-Origin' missing
4. Reason: CORS header 'Origin' cannot be added
5. Reason: CORS preflight channel did not succeed
6. Reason: CORS request did not succeed
7. Reason: CORS request external redirect not allowed
8. Reason: CORS request not HTTP
9. Reason: Credential is not supported if the CORS header
'Access-Control-Allow-Origin' is '*'
10. Reason: Did not find method in CORS header
'Access-Control-Allow-Methods'
11. Reason: expected 'true' in CORS header
'Access-Control-Allow-Credentials'
12. Reason: invalid token 'xyz' in CORS header
'Access-Control-Allow-Headers'
13. Reason: invalid token 'xyz' in CORS header
'Access-Control-Allow-Methods'
14. Reason: missing token 'xyz' in CORS header
'Access-Control-Allow-Headers' from CORS preflight channel
15. Reason: Multiple CORS header 'Access-Control-Allow-Origin' not allowed

23. Permissions-Policy directives
1. Permissions-Policy: accelerometer Experimental
2. Permissions-Policy: ambient-light-sensor Experimental
3. Permissions-Policy: attribution-reporting Experimental
4. Permissions-Policy: autoplay Experimental
5. Permissions-Policy: bluetooth Experimental
6. Permissions-Policy: browsing-topics Experimental Non-standard
7. Permissions-Policy: camera
8. Permissions-Policy: compute-pressure Experimental
9. Permissions-Policy: display-capture
10. Permissions-Policy: document-domain Experimental
11. Permissions-Policy: encrypted-media Experimental
12. Permissions-Policy: fullscreen
13. Permissions-Policy: gamepad Experimental
14. Permissions-Policy: geolocation
15. Permissions-Policy: gyroscope Experimental
16. Permissions-Policy: hid Experimental
17. Permissions-Policy: identity-credentials-get Experimental
18. Permissions-Policy: idle-detection Experimental
19. Permissions-Policy: local-fonts Experimental
20. Permissions-Policy: magnetometer Experimental
21. Permissions-Policy: microphone
22. Permissions-Policy: midi Experimental
23. Permissions-Policy: otp-credentials Experimental
24. Permissions-Policy: payment Experimental
25. Permissions-Policy: picture-in-picture Experimental
26. Permissions-Policy: publickey-credentials-create Experimental
27. Permissions-Policy: publickey-credentials-get
28. Permissions-Policy: screen-wake-lock
29. Permissions-Policy: serial Experimental
30. Permissions-Policy: speaker-selection Experimental
31. Permissions-Policy: storage-access Experimental
32. Permissions-Policy: usb Experimental
33. Permissions-Policy: web-share
34. Permissions-Policy: window-management Experimental
35. Permissions-Policy: xr-spatial-tracking Experimental

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IN THIS ARTICLE

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USER-AGENT

The User-Agent request header is a characteristic string that lets servers and
network peers identify the application, operating system, vendor, and/or version
of the requesting user agent.

Warning: Please read Browser detection using the user agent for why serving
different Web pages or services to different browsers is usually a bad idea.

Header type Request header Forbidden header name no

SYNTAX

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User-Agent: <product> / <product-version> <comment>

Common format for web browsers:

httpCopy to Clipboard

User-Agent: Mozilla/5.0 (<system-information>) <platform> (<platform-details>) <extensions>

DIRECTIVES

A product identifier — its name or development codename.

<product-version>

Version number of the product.

Zero or more comments containing more details. For example, sub-product
information.

FIREFOX UA STRING

For more on Firefox- and Gecko-based user agent strings, see the Firefox user
agent string reference. The UA string of Firefox is broken down into 4
components:

Mozilla/5.0 (platform; rv:geckoversion) Gecko/geckotrail Firefox/firefoxversion

1. Mozilla/5.0 is the general token that says that the browser is
Mozilla-compatible. For historical reasons, almost every browser today sends
it.
2. platform describes the native platform that the browser is running on
(Windows, Mac, Linux, Android, etc.) and if it is a mobile phone. Firefox OS
phones say Mobile — the web is the platform. Note that platform can consist
of multiple ";"-separated tokens. See below for further details and
examples.
3. rv:geckoversion indicates the release version of Gecko (such as "17.0"). In
recent browsers, geckoversion is the same as firefoxversion.
4. Gecko/geckotrail indicates that the browser is based on Gecko. (On the
desktop, geckotrail is always the fixed string 20100101.)
5. Firefox/firefoxversion indicates that the browser is Firefox and provides
the version (such as "17.0").

EXAMPLES

Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:47.0) Gecko/20100101 Firefox/47.0
Mozilla/5.0 (Macintosh; Intel Mac OS X x.y; rv:42.0) Gecko/20100101 Firefox/42.0

CHROME UA STRING

The Chrome (or Chromium/Blink-based engines) user agent string is similar to
Firefox's. For compatibility, it adds strings like KHTML, like Gecko and Safari.

EXAMPLES

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36

OPERA UA STRING

The Opera browser is also based on the Blink engine, which is why it almost
looks the same as the Chrome UA string, but adds "OPR/<version>".

EXAMPLES

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.106 Safari/537.36 OPR/38.0.2220.41

Older, Presto-based Opera releases used:

Opera/9.80 (Macintosh; Intel Mac OS X; U; en) Presto/2.2.15 Version/10.00
Opera/9.60 (Windows NT 6.0; U; en) Presto/2.1.1

MICROSOFT EDGE UA STRING

The Edge browser is also based on the Blink engine. It adds "Edg/<version>".

EXAMPLES

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36 Edg/91.0.864.59

SAFARI UA STRING

In this example, the user agent string is mobile Safari's version. It contains
the word "Mobile".

EXAMPLES

Mozilla/5.0 (iPhone; CPU iPhone OS 13_5_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.1.1 Mobile/15E148 Safari/604.1

CRAWLER AND BOT UA STRINGS

EXAMPLES

Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)

Mozilla/5.0 (compatible; YandexAccessibilityBot/3.0; +http://yandex.com/bots)

LIBRARY AND NET TOOL UA STRINGS

EXAMPLES

curl/7.64.1

PostmanRuntime/7.26.5

SPECIFICATIONS

SpecificationHTTP Semantics
# field.user-agent

BROWSER COMPATIBILITY

Report problems with this compatibility data on GitHub

desktopmobile
Chrome

Edge

Firefox

Opera

Safari

Chrome Android

Firefox for Android

Opera Android

Safari on iOS

Samsung Internet

WebView Android

WebView on iOS

User-Agent
Full support
Chrome1
Toggle history
Full support
Edge12
Toggle history
Full support
Firefox1
Toggle history
Full support
Opera15
Toggle history
Full support
Safari1
Toggle history
Full support
Chrome Android18
Toggle history
Full support
Firefox for Android4
Toggle history
Full support
Opera Android14
Toggle history
Full support
Safari on iOS1
Toggle history
Full support
Samsung Internet1.0
Toggle history
Full support
WebView Android4.4
Toggle history
Full support
WebView on iOS1
Toggle history

LEGEND

Tip: you can click/tap on a cell for more information.

Full supportFull support
The compatibility table on this page is generated from structured data. If you'd
like to contribute to the data, please check out
https://github.com/mdn/browser-compat-data and send us a pull request.

developer.mozilla.org Open in urlscan Pro 2600:1901:0:ab4c:: Public Scan

Form analysis 1 forms found in the DOM

/en-US/search

Text Content

developer.mozilla.org Open in urlscan Pro
2600:1901:0:ab4c:: Public Scan

Form analysis
1 forms found in the DOM